Planigale kendricki & Planigale tealei: Two new species of Dasyurid Marsupial from the Pilbara Region of Western Australia.

Among Mammals, the most diverse groups tend to be those which feed on Insects. In Australia, about a quarter of all land Mammals belong to the Dasyuridae, which ate insectivorous and sometimes carnivorous Marsupials. The genus Planigale currently contains four species of Shrew-like insectivorous Marsupials, weighing between 3 and 17 g, which are found across most of the continent, with a fifth species on the island of New Guinea, although molecular studies have suggested that the genus probably contains more diversity than is reflected in this classification. Australia's indigenous Mammals have suffered greatly since the arrival of Europeans, with sharp declines in their numbers still being seen even in parts of the continent with few Human visitors, which makes having an accurate inventory of Australian Mammal species essential to conservation efforts.

The four currently described species of Planigale from Australia, Planigale gilesi, Planigale maculata, Planigale ingrami, and Planigale tenuirostris, are widely distributed in northern and eastern Australia. None of these species are considered to be threatened, but the two most widespread species, Planigale ingrami, and Planigale tenuirostris, have been shown to contain very high levels of genetic diversity, which may indicate that they are actually multiple species with much smaller ranges, and therefore potentially at conservation risk. 

The last major revision of the genus Planigale was carried out in 1976 by zoologist Michael Arche, but since that time genetic methods have become available, with several studies having suggested that there might be one or two undescribed species belonging to the genus present in the Pilbara Region of northerm Western Australia.

In a paper published in the journal Zootaxa on 14 August 2023, Linette Umbrello of the School of Biology and Environmental Science at the Queensland University of Technology, and Collections and Research at the Western Australian Museum, Norah Cooper, also of Collections and Research at the Western Australian Museum, Mark Adams of the Department of Biological Sciences at the University of Adelaide, and the Evolutionary Biology Unit at the South Australian Museum, Kenny Travouillon, again of Collections and Research at the Western Australian Museum, Andrew Baker, also of the School of Biology and Environmental Science at the Queensland University of Technology, and of the Biodiversity and Geosciences Program at Queensland Museum, Mike Westerman of the Department of Environment and Genetics at La Trobe University, and Ken Alpin, again of Collections and Research at the Western Australian Museum, and of the Australian Museum Research Institute at the Australian Museum, formally describe two new species of Planigale from the Pilbara Region.

The approximate distributions of the four currently recognised species of Australian Planigale with Pilbara distributions indicated with arrows. Umbrello et al. (2023).

The first new species described was originally identified as a candidate species in the first ever genetic study of the group, published 1995, in which a team led by Jodie Painter of La Trobe University used the mitochondrial cytichrome b gene to determine the relationships between different species within the genus Planigale. At the time. the candidate species, identified only as Planigale 1, was known from only a single specimen, which was one of only two specimens from Pilbara included in the study (the other specimen was also identified as a new species, Planigale 2, but was later found to belong to a separate genus), but subsequent genetic studies have consistently recovered this species as a separate clade.

Umbrello et al. formally name Planigale 1 as Planigale kendricki, in honour of Peter Kendrick, in recognition of his major contribution to the understanding of the vertebrate fauna of north-western Australia. Planigale kendricki is large for a species of Planigale, with a maximum recorded weight of 12.5 g and a maximum recorded length of 74 mm (excluding the tail). Females are smaller than the males, with a maximum recorded weight of 9.5 g and a maximum recorded length of 69 mm. It is more reddish than other species of the genus, with its back and flanks covered by a thick coat of orange-tan fur with patches of dark brown, while the hair of the underside is grey, changing to yellow or even brown at the tips.

Planigale kendricki. Note the rufous, orange-tan colouration of the fur and the orange eye ring.  Roy Teale in Umbrello et al. (2023).

Planigale kendricki is found across the Pilbara and the surrounding area of northern Western Australia, including the Cape range Peninsula, Ashburton and Gascoyne regions, with specimens reported from the Great Sandy Desert and Little Sandy Desert, Lake Auld, and Mandora near Eighty Mile Beach. It appears to favour areas with exposed bedrock, including sandy plains, scree slopes and rocky creek beds. 

Proposed distribution of Planigale kendricki inferred from specimens at the western Australian Museum (blue dots) that were examined during this study. the border of the Pilbara region is shown by the dashed line in inset A. Umbrello et al. (2023).

The second new species was first identified as a candidate species in a study led by Mark Blacket of La Trobe University and published in 2000, in which a much larger selection of Planigale specimens were examined, and a phylogeny for the genus developed using the 12S rrNA gene sequence. Blacket et al. identified this candidate species as Planigale Mt Tom Price, in reference to the area where it was discovered. This species was also recovered by subsequent genetic studies in 2009, 2016, and 2020, which looked at different gene sets.

Umbrello et al. formally name Planigale Mt Tom Price as Planigale tealei, in honour of Roy Teale, for his support for the work of the Western Australian Museum over many decades, and for collecting many of the specimens on which the description of the species is based. Planigale tealei is small for a species of Planigale, with a maximum male size of 6.1 g and 62.5 mm in length (excluding the tail), and a maximum female size of 4.7 g and 60 mm in length. Its back and sides are covered with a thick, greyish brown coat, paler on the flanks, and pale on the underside.

Planigale tealei (WAM M62896). Linette Umbrello in Umbrello et al. (2023).

Planigale tealei appears to be largely restricted to the Pilbara Region, with very few records outside of the area. It us usually encountered on cracked clay soils in areas with plenty of exposed rocky outcrops, preferring more clay-rich soils.

Proposed  distribution  of Planigale  tealei  inferred  from  specimens  (pink  triangles)  in  the western  Australian Museum that were examined during this study, including southern locality of Waldburg Station. the border of the Pilbara is shown by a dotted line in Inset A. Umbrello et al. (2023).

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Tuebingosaurus maierfritzorum: A new species of Massopodan Sauropodomorph Dinosaur from the Palaeontological Collection of the University of Tübingen.

The Palaeontological Collection of the University of Tübingen contains one of the largest assemblages of Sauropodomorph Dinosaurs in Europe, but also one of the least studied. Much of this material was collected from sites around Tübingen, Aixheim and Löwenstein in the nineteenth and early twentieth centuries and classified under the genus Plateosaurus. 

The genus Plateosaurus was once used to classify almost all non-Sauropod Sauropodomorph Dinosaurs, and by the mid twentieth century contained over 20 species, of which only four are considered valid today. Unfortunately, while it is now recognised that the non-Sauropod Sauropodomorph Dinosaurs are a more diverse group than once understood, and that understanding this diversity is the key to understanding the emergence of the true Sauropods, one of the most remarkable groups of organisms ever to appear on Earth, several rival schemes for the classification of this group have appeared, hampering this understanding.

In a paper published in the journal Vertebrate Zoology on 8 September 2022, Omar Rafael Regalado Fernández of the Fachbereich Geowissenschaften an der Universität Tübingen, and Ingmar Werneburg, also of the Fachbereich Geowissenschaften an der Universität Tübingen, and of the Senckenberg Centre for Human Evolution and Palaeoenvironment an der Universität Tübingen, describe a new species of Sauropodomorph Dinosaur from the Palaeontological Collection of the University of Tübingen, based upon a specimen, GPIT-PV-30787, collected from Lower Dinosaur Bed at Obere Mühle in 1932.

The complex nature of Sauropodomorph Dinosaur taxonomy meant that Regalado Fernández and Werneburg were obliged to carry out multiple phylogenetic analyses in order to try to accommodate specimen GPIT-PV-30787 into the competing phylogenies for the group. Fortunately, these produced reasonably consistent results, with the specimen being found to be closely related to Schleitheimia schutzi, making it a Massopodan Sauropodomorph, close to the origin of the true Sauropods.

Based upon this information, Regalado Fernández and Werneburg describe specimen GPIT-PV-30787 as the holotype of a new species, giving it the name Tuebingosaurus maierfritzorum, where 'Tuebingosaurus' refers to Tübingen and 'maierfritzorum' honours Wolfgang Maier, professor of evolutionary zoology in Tübingen from 1987 to 2007, and Uwe Fritz, former editor-in-chief of the journal Vertebrate Zoology.

Specimen GPIT-PV-30787 comprises a complete pelvis (three sacral vertebrae, two ilia, two pubes, two ischia), five anterior caudal vertebrae, four chevrons, left femur, left tibia, left and right fibulae, left astragalus, left calcaneum, metatarsal I, and pedal fingers 3 and 4.

Reconstruction of Tuebingosaurus maierfritzorum, as a quadruped Dinosaur, using the outline of Riojasaurus as a base, next to the silhouette of Friedrich von Huene. The drawing of the bones is based on and modified from the original illustrations of specimen 'GPIT IV' (the name originally ascribed to GPIT-PV-30787) by von Huene. The right fibula is marked in grey as it was found nearby with similar measurements to the left fibula and has been assumed to be part of the same individual. Regalado Fernández & Werneburg (2022).

Regalado Fernández and Werneburg's phylogeny suggests that Tuebingosaurus maierfritzorum is a Massopodan, making it the earliest member of the group known from the Upper Triassic Trossingen Beds. Despite this taxonomic placement, Tuebingosaurus maierfritzorum still shares a number of features more generally associated with Plateosaurian Sauropodomorphs, most notably a heel-like projection in the posterior part of the ischiadic peduncle of the ilium and a straight lateral margin in metatarsal II, features which led to the assumption that this was a specimen of Plateosaurus. 

This presence of Plateosaurian-like features in early Massopodan Dinosaurs is unlikely to be unique to Tuebingosaurus maierfritzorum, and re-examination of other historic specimens at Tübingen and other palaeontological collections may provide more examples, helping to unravel the origins of the Sauropods.

Reconstruction of the last moments in the life of Tuebingosaurus maierfritzorum (collection number of the painting: GPIT-PV-41827). The cortical bone on the left side of the fossil is fractured into flakes, which can be explained if the carcass was exposed over a long time on the mud, two to four years, before being buried – in the reconstruction, the Animal will fall to its right body side. The reconstruction shows the animal sinking in a mud trap, attacked by a Rauisuchian, Teratosaurus, which has also been found in the Trossingen Formation in Baden-Württemberg. In the background, a herd of Plateosaurus trossingensis runs away from the scene. The flora in the swamp is reconstructed based on fossils from the Germanic basin, with shoots of Horsetails and Ferns covering the swamp and a forest comprising Cycads (Taeniopteris), Lycophytes (Lepacyclotes) and Coniferous Plants (Brachyphyllum). Regalado Fernández & Werneburg (2022).

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Bulbophyllum mamasaense: A new species of Epidendroid Orchid from Sulawesi.

Epidendroid Orchids, Epidendroideae, are the largest subfamily of Orchids, with over 15 000 described species, more than all other Orchid groups combined. The majority of these species are epiphytic (live on other plants, typically in the canopy of rainforest trees), though terrestrial forms are known. The group is found across the globe, with the exception of the polar regions, the deserts of Africa, Arabia and Australia, and the southern part of South America. The genus Bulbophyllum contains around 2200 described species from tropical regions around the world, including about 1600 species from Asia, and is thought likely to contain many more undescribed species. Members of the genus can be very difficult to tell apart when they are not in flower, as their vegetative parts tend to be much reduced, often with only a single leaf emerging from a pseudobulb (a pseudobulb, like a bulb, is an enlarged stem base used as a food store by a plant during dormant periods, but unlike a bulb is not found in the soil).

In a paper published in the journal Taiwania on 10 January 2022, Aninda Retno Utami Wibowo of the Bali Botanic Garden of the Indonesian National Research and Innovation Agency, Jeffrey Champion of the Herbarium Bogoriense of the Indonesian National Research and Innovation Agency, and Lina Susanti Juswara of Candikuning, Bali, describe a new species of Bulbophyllum from Sulawesi.

The new species is named Bulbophyllum mamasaense, where 'mamasaense' means 'from Mamasa' in reference to the Mamasa Regency of West Sulawesi Province, where the species was discovered. Only a single wild population of the species has been discovered, in Mesawa District of Mamasa Regency, but the species appears to do well in cultivation, and has been traded commercially for some years.

 

Photographs of Bulbophyllum mamasaense. (A) Habit, (B) flowers on rachis, (C) flower, oblique view, stelidia indicated with the red arrow, (D) flower, top view after median sepal removal, (E) fruits. Scale bars: (A) 10 cm; (B) 5 mm; (C) and (D) are 1 mm; (E) is 5 mm. Jeffrey Champion and Aninda Retno Utami Wibowo in Wibowo et al. (2022).

Bulbophyllum mamasaense produces three distinct, closely arranged, ovate–oblong pseudobulbs (storage organs derived from a thickening of the part of a stem between leaf nodes) from a creeping rhizome, with smooth, wiry roots spreading below the pseudobulbs, and oblong leaves, 16-16.5 cm long and 5.3-5.5 cm wide above. Flowers are born on pendulous inflorescences arising from the base side of the pseudobulb. Each inflorescence can bear up to 165 flowers, densely packed in eight rows, which open similtaneously.

 

Illustration of Bulbophyllum mamasaense. (A) Habit, (B) leaf, (C) inflorescence, (D) flower, oblique view, (E) flower, top view after median sepal removed, (F) column and lip, (G) flower bract, (H) dorsal sepal, (I) lateral sepals, (J) petal, (K) lip, (L) lip, flattened, (M) lip, oblique view showing canal, (N) column, ventral view, (O) anther cap, ventral view, (P) Pollinia in pairs. Scale bars: (A) 5 cm; (B) 5 cm; (C) 2 cm; (D), (E), (F) 5 mm; (G) 1 mm; (H) 2 mm; (I) 5 mm; (J), (K), (L), (M), (N) 2 mm; (O) 1 mm; (P) 0.2 mm. Aninda Retno Utami Wibowo in Wibowo et al. (2022).

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Identifying fragmentary Mammal teeth from the Early Eocene of Ellesmere Island, Canada.

Lower Eocene (Wasatchian-aged) strata of the Margaret Formation, Eureka Sound Group on Ellesmere Island, Nunavut preserve evidence of lush mixed conifer-broadleaf rainforests inhabited by Alligators, Turtles, Birds, and at least 25 Mammalian genera. First discovered in 1975 near the head of Strathcona Fiord, the vertebrate fossils in the Eureka Sound Group are few, fragmentary and weather-worn, which can make it challenging to identify them. By far the most abundant and diverse Vertebrate fossils have come from the Margaret Formation cropping out on the Matthew peninsula between Bay and Strathcona fiords. Nearly a century before the first discovery of Eocene Vertebrate fossils on Ellesmere, Eocene Arctic forests were first documented when Sergeant David Brainard, a survivor of the ill-fated Greely Expedition of 1881–1883, discovered petrified logs on northeastern Ellesmere Island. Among the best preserved, extensive, and photogenic of the Eocene Arctic fossil forests is the Strathcona Fiord Fossil Forest, which preserves permineralised in situ tree stumps protruding from a prominent coal seam. The tree stumps are large, with diameters ranging from 40 cm to over a meter, and closely spaced, indicating a dense forest comparable to today’s Cypress swamps in the southern United States. Eocene Arctic palaeotemperature estimates using multiple proxies suggest a mean annual temperature of 5–17˚C, with winters above freezing and summer temperatures above 20˚C. Further, the Eocene Arctic rainforests had high mean annual precipitation and humidity, comparable with today’s temperate rainforests along the North American west coast.

In the summers of 2010 and 2018, Jaelyn Eberle of the Museum of Natural History and Department of Geological Sciences at the University of Colorado, David Eberth of the Royal Tyrrell Museum and team recovered tooth fragments belonging to a Mammal and small, undiagnostic bone fragments at the Strathcona Fiord Fossil Forest. As far as they are aware, these are the first Vertebrate fossils documented from this fossil forest. Most fossil Mammals can be identified to genus and often species by dental morphology. However, the tooth fragments from the Strathcona Fiord Fossil Forest are so incomplete as to be undiagnostic by using their external morphology. Therefore, Eberle et al. analysed the tooth enamel microstructure to assist in identifying the fossils. Mammalian prismatic enamel, the hardest and most resistant material in the body, consistently differs in its microstructure among clades of Perissodactyla (odd-toed ungulates), Rodentia, Proboscidea, in a paper published in the journal PLoS One on 23 September 2020, Jaelyn Eberle, Wighart von Koenigswald of the Institute of Geosciences at the Rheinische Friedrich-Wilhelms University, and David Eberth, demonstrate that the tooth fragments from the Strathcona Fiord Fossil Forest can be identified to genus based on their enamel microstructure. In so doing, they (1) document the first fossil Mammal from the Strathcona Fiord Fossil Forest; (2) help refine the age and correlation of this site within the context of the Margaret Formation elsewhere on Ellesmere Island; and (3) underscore the utility of tooth enamel microstructure in identifying Mammalian tooth fragments that cannot be identified by traditional palaeontologic means.

The tooth fragments described below were recovered from Locality P201088-2(NU) on central Ellesmere Island, along the southwestern coastal region of Strathcona Fiord. The general area, referred to as 'Strathcona Fiord', includes the first two fossil vertebrate sites that were discovered in the Canadian Arctic (Ellesmere Island) by Mary Dawson and her colleagues in the 1970s, approximately 10–12 km southeast and northeast of locality P201088-2(NU).

 

Map of Canada (inset) and satellite image showing location of the Strathcona Fiord study area and measured section. Eberle et al. (2020).

The sharp-based sandstone that hosts locality P201088-2(NU) occurs less than a meter above the top of an approximately 2 m thick coal that preserves an assemblage of in situ permineralised tree stumps and root balls coined the Strathcona Fiord Fossil Forest.

 

Images of the Strathcona Fiord Fossil Forest and fossil vertebrate site P201088-2(NU). (A) P201088-2(NU) is less than a meter stratigraphically above the coal containing the fossil forest; (B) and (C) show close-ups of petrified tree stumps in the fossil forest. Eberle et al. (2020).

Vertebrate fossils in the Strathcona Fiord region produce from the Eureka Sound Group, which consists of four formations in this area. In ascending order, these are the Mount Bell, Mount Lawson, Mount Moore, and Margaret formations. The stratigraphic section that Eberle et al. examined and measured at Strathcona Fiord consists of the uppermost exposures of the fine-grained marine Mount Moore Formation, overlain by non-coaly to coaly, paralic-to-non-marine deposits of the lower Margaret Formation. Eberle et al. place locality P201088-2(NU) approximately 316 m above the base of the multi-kilometer-thick Margaret Formation. Based on thickness data Eberle et al. regard this position as occurring in the lower portion of the Margaret Formation. Beds in this portion of the section are exposed along an extensive north-south trending ridge, and dip steeply (25˚–35˚) to the west. Lastly, Eberle et al. note that during stratigraphic measurement and examination in their study area, they identified errors in formation identification on the geologic map. Specifically, previous authors had erroneously mapped the Strathcona Fiord Fossil Forest and its thick coal as part of the Mount Lawson Formation, which instead is a Palaeocene-aged marine mudstone succession in the lower half of the Eureka Sound Group.

 

Strathcona Fiord Section showing stratigraphic level of fossil vertebrate locality P2011088-2 (NU) and Strathcona Fiord Fossil Forest in the coal directly below it. Eberle et al. (2020).

Strathcona Fiord fossil vertebrate sites have previously been interpreted as early Eocene (Wasatchian) in age. Based on these interpretations and stratigraphic patterns, Eberle et al. suggest the age of the Strathcona Fiord Fossil Forest and locality P201088-2(NU) is also Wasatchian, equivalent in time to the lower Margaret Formation interval at Bay Fiord (about 25 kilometers to the north-northeast).

Locality P201088-2(NU) occurs just above the stratigraphic horizon where the Margaret Formation paralic succession (complexly and thinly interbedded marine to non-marine strata) transitions up-section into a 50 m thick succession of strictly non-marine, coastal-plain strata dominated by fine sandstones and minor coals. Exposures of the lower Margaret Formation at Bay Fiord record a similar pattern of overall regression and are characterized by an upsection transition from paralic to coaly coastal plain deposits. The host sandstone for locality P201088-2(NU) exhibits ripple laminae and abundant coalified root traces, the latter indicating that a stable and likely subaerial substrate was present for Plant colonisation subsequent to deposition of the sandstone. Sparse occurrences of fossil Vertebrate fragments are present among mudstone and ironstone intraclasts in the sandstone, suggesting that lower portions of the sandstone may have been deposited as a lag deposit during waning flow. Angiosperm and Gymnosperm leaf fragments, and more root traces are common in the uppermost portions of the host sandstone, again suggesting substrate stability between subsequent later-stage sediment accumulation events.

No other intervals were observed lower in section that preserve well-developed associations of ‘fossil forests,’ ironstone and fossil Vertebrate clasts, rooted horizons, fossil leaves, and an absence of marine indicators. Furthermore, the presence of the fossil forest, multiple rooted horizons, leaf fossils, and ironstone and fossil bioclasts (the tooth fragments) all suggest forested conditions, exposed substrates, and incipient soil formation in a well-saturated setting subjected to episodic flooding. Accordingly, Eberle et al. interpret this transitional stratigraphic interval as recording an up-section shift from frequently flooded paralic shoreline settings to a relatively more up-dip coastal-plain setting where non-marine conditions prevailed. This palaeoenvironmental interpretation matches those previous hypothesised for the Margaret Formation that describe upward-coarsening cycles of interbedded cross-bedded sandstone, siltstone, mudstone, and coal. These are interpreted as proximal delta-front to delta-plain palqeoenvironments characterised by abundant shoreline sands, alluvial to estuarine channels, coal swamps, lagoons and bays, and well-forested, low-gradient interfluves.

Nunavut Fossil Vertebrate (i.e., NUFV) 2092B and 2092E, the tooth fragments analysed in Eberle et al.'s study, were collected along with approximately 20 other tooth fragments and several small, weathered bone fragments by Jaelyn Eberle, David Eberth, and team in July 2010 and by Jaelyn Eberle in July 2018 at locality P201088-2(NU). The fossils were collected on Class 2 Nunavut Territory Palaeontologist Permits 2010-003P and 2018-02P issued by the Nunavut Department of Culture and Heritage. Detailed coordinates for locality P201088-2(NU) are on file at the Nunavut Department of Culture and Heritage in Iqaluit and the Canadian Museum of Nature in Ottawa, Canada.

 

Tooth fragments from locality P201088-2(NU) at the Strathcona Fiord Fossil Forest site on central

Ellesmere Island, Nunavut. (A) NUFV 2092B. (B) NUFV 2092E. Eberle et al. (2020).

Given their similarity in thickness and external appearance, and the fact that they were recovered near one another, the tooth fragments probably represent the same taxon and individual. Based upon their thickness, NUFV 2092B and 2092E are from a relatively large Mammal. However, their external morphology does not allow us to reliably identify the Mammal to which they belong. Therefore, Eberle et al. decided to study the enamel microstructure. To investigate the microstructure of NUFV 2092B and 2092E, three traditional planes of section were studied, the horizontal (or transverse), vertical, and tangential sections.

 

Orientation of the three traditional planes of section used to study mammalian tooth enamel microstructure from. Eberle et al. (2020).

NUFV 2092B and 2092E were studied under a light microscope to orient the specimens and determine the direction of the occlusal surface. The specimens were subsequently embedded in epoxy resin, and oriented so that the desired sections (horizontal, vertical, or tangential) were placed parallel to the resin surface. The embedded specimens were left for 48 hours at room temperature under a fume hood to allow the epoxy to harden. NUFV 2092B was cut using an Isomet© low-speed saw with 0.3 mm blade thickness, to produce horizontal and vertical sections, whereas NUFV 2092E was used for the tangential section. The specimens were ground in three steps. First, they were ground down to the enamel surface using a grinding wheel (grit 240). Next, handgrinding was done on fine wet sandpaper (grit 800) placed over a glass sheet, and finally the specimens were ground with fine powder grit (grit 1000) mixed with water on a glass plate. Between each of these steps, the specimens were analysed under a light microscope to ensure that grinding was not too extensive. The ground surfaces were rinsed with water, cleaned in an ultrasonic cleaner, blown dry, and etched with 10% hydrochloric acid for approximately three seconds.

Prior to scanning electron microscope analysis, the specimens were sputter-coated with gold or palladium. Scanning electron microscope analysis was conducted on a Camscan MV 2300 instrument in the Palaeontology Section of the Institute of Geosciences and a Cambridge Stereoscan 200 scanning electron microscope in the Institut für Biodiversität der Pflanzen at the Rheinische Friedrich-Wilhelms University in Bonn, Germany.

In describing the enamel microstructure of NUFV 2092B and 2092E, Eberle et al. define the units by their size and level of complexity. First, they describe the crystallites, the smallest units of enamel that are comprised of fine needles of hydroxyapatite with a diameter of less than 0.5 μm and length of more than 100 μm. Crystallites are visible under high magnification (1500x and higher). Next, Eberle et al. describe the prisms that are made up of bundles of crystallites surrounded by a prism sheath. The size and shape of the prisms differ among clades of Mammals. Prisms form at the enamel-dentine junction and grow almost to the outer enamel surface. They are typically arranged in groups or bands with the same prism orientation. Their orientation defines the various enamel types. The prismatic enamels of Mammals often have two or more different enamel types. The most primitive enamel type among placental Mammals is radial enamel, in which the prisms’ long axes parallel one another and extend radially from near the enamel-dentine junction towards the outer enamel surface. More complex enamel types occur in which bands of prisms change their orientations from the enamel-dentine junction to the outer enamel surface. Among the most often described enamel types are Hunter-Schreger bands, which are light and dark stripes often seen under a light microscope. Hunter-Schreger bands are an optical phenomenon caused by the different prism orientation in alternating bands, forming decussations. Hunter-Schreger bands occur in the enamel of most large Mammals and often are arranged horizontally. However, a few taxa, including Rhinocerotoids, have vertical Hunter-Schreger bands. Hunter-Schreger bands function as a crack-stopping device. The level above the enamel type is the schmelzmuster, the three-dimensional distribution of enamel types within the enamel that has both biomechanical and phylogenetic controls. The number of possible combinations of enamel types or schmelzmusters is very large.

By studying the horizontal, vertical, and tangential sections of NUFV 2092B and 2092E, Eberle et al. discovered a complex enamel microstructure that was challenging to interpret solely through scanning electron microscope analysis. Consequently, they also studied NUFV 2092B and 2092E at lower magnification under a light microscope using the light-guide effect. If light hits an enamel prism approximately perpendicular to its axis, the light is reflected and the prism appears light in color. If, however, the light hits a prism parallel to its long axis, it disappears into the prism, and the prism appears dark. When the source of illumination is changed from one direction to another, bands that were dark in one will be light in the other, and vice versa. The light and dark bands, each comprised of many prisms with the same orientation, are the Hunter-Schreger bands. Eberle et al. used a combination of the light-guide effect and scanning electron microscope analysis to study the enamel microstructure of NUFV 2092B and 2092E.

Based upon thickness, NUVF 2092B and 2092E belong to a relatively large Mammal. The shiny outer surface of the enamel is covered by ridges and crenulations that extend vertically and diagonally at a steep angle. Of the diverse Mammalian fauna known from the early Eocene Arctic, the Pantodont Coryphodon is among the largest and best represented by fossils, and the enamel on its teeth has vertical ridges and wrinkles. However, these characters are not unique to Coryphodon. Many Mammals, including Brontotheres that also are known from the Eocene Arctic, show varying amounts of rugosity and crenulations on the external surface of the enamel.

Others have noted the appearance of vertical stripes in the tangential section of the enamel of Coryphodon as well as ridges on the shearing crests of its molars, indicating the presence of vertical structures within the enamel. On the occlusal surface of NUFV 2092B, there are weak ridges, and when the tangential section of the enamel is illuminated from one side, faint vertical light and dark stripes are visible. However, these characters also are not restricted to Coryphodon, but occur in Rhinocerotoids and some extinct South American Mammals including Pyrotheres and Astrapotheres.

Coryphodon, however, is characterised by a unique and complex enamel microstructure coined Coryphodon-enamel. NUFV 2092B and 2092E were analysed at low and high magnifications under both a light microscope and scanning electron microscope to determine whether Coryphodon-enamel is present. Eberle et al. describe the crystallites, prisms, and schmelzmuster of the NUFV specimens, and compare them to the enamel microstructure of Coryphodon, Rhinocerotoids and other large Mammals known from the Eocene Arctic.

The cross sections of prisms are best seen in the tangential section. Individual crystallites are visible at high magnification, where they appear as fine needles making up the prisms and interprismatic matrix. The crystallites in the prisms appear approximately parallel to those comprising the interprismatic matrix, which is found in the enamel of Coryphodon. Most of the prisms in NUFV 2092E are rounded and have an open prism sheath, although there is some variability in shape, with some prisms being more oblong and narrowing towards the top. The prisms range in diameter from approximately 4–7 μm and the prism sheaths are open towards the base of the tooth or to one side. A horseshoe-shaped prism sheath was noted for Coryphodon, although it is not restricted to the genus. Although close together, the prism sheaths do not appear to touch one another. Rather, a thin (roughly 1–2 μm) layer of interprismatic matrix surrounds the prism sheaths and appears as a ‘tail’ below each prism that tapers towards the base of the tooth or to the side.

 

Scanning electron microscope images of the tangential section of NUFV 2092E. (A) Cross-section through prisms; the prism sheath is dark and looks like a trench around each prism because it has been etched away. (B) Close-up of prisms and interprismatic matrix which are comprised of fine, needle-like crystallites. P, prism. Eberle et al. (2020).

The combined interpretation of the transverse, vertical, and tangential sections of NUFV 2092B and 2092E indicates that the enamel microstructure is dominated by elongate, steeply dipping or near vertical bodies of prisms that penetrate the enamel almost from the enamel-dentine junction towards the outer enamel surface, leaving thin inner and outermost zones.

Next to the enamel-dentine junction, there is a thin inner zone of radial enamel in some places. However, in other areas next to the enamel-dentine junction the prisms do not appear to run parallel to one another, and it is difficult to discern a pattern.

The middle zone, which comprises the greatest thickness of enamel, is made up of a complex enamel wherein elongate bodies of variable thickness extend outward from the enamel-dentine junction towards the outer enamel surface. At higher magnification, the elongate bodies are Hunter-Schreger band-like in that they are comprised of steeply-dipping or rising prisms, and are separated from one another by transitional zones of horizontal (or nearly so) prisms. The nearly vertical orientation of the elongate bodies becomes obvious in the tangential section (discussed below). However, in contrast to Hunter-Schreger bands that are identified in many large Mammals, the elongate bodies and intervening transitional zones are not of uniform thickness or spacing from one another in NUFV 2092B.

 

Scanning electron microscope image of enamel of NUFV 2092B in horizontal section. (A) Three enamel zones are evident; a very thin Inner Zone of radial enamel (in some places), a thick Middle Zone comprised of elongate bodies of prisms, and a thin Outer Zone. (B) Higher magnification scanning electron microscope image showing area outlined by white square in (A); elongate bodies (eb) are comprised of steeply-dipping or rising prisms, and are separated from one another by transitional zones (tz) made up of horizontal (or nearly so) prisms. Irregular-shaped grains on scanning electron microscope images are an artifact of sample preparation process. Eberle et al. (2020).

Based on the tangential section, Eberle et al. predict that the nested chevrons should appear in cross section as vertical elongate bodies with variable thicknesses and branches, depending upon where the horizontal section transects them. Further, Eberle et al. predict that they should be concentrated in the inner region of the middle zone of enamel. Whereas, in the outer region of the middle zone (towards the outer enamel surface) in horizontal section, Eberle et al. hypothesise that the elongate bodies should be broader in appearance, and the nested chevron structures should all but disappear in the outermost zone of enamel. In fact, the horizontal section appears to show just that, the outer region of the middle enamel zone shows broader bodies that transition in places into radial enamel near the outer enamel surface.

 

Uncoated tangential section of NUFV 2092E under a light microscope (A) and higher magnification (B). In both images, occlusal surface is towards the top and source of light is from the bottom. EDJ, Enamel-Dentine Junction; OES, outer enamel surface. Eberle et al. (2020).

Evident in vertical sections of NUFV 2092B, an outer zone of radial enamel in which the prisms run parallel to each other lies near the outer enamel surface. In some areas, it may be up to 300 μm in thickness, whereas in other areas it is much thinner, and the microstructures of the thick middle zone extend nearly to the outer enamel surface. In some areas adjacent to the outer enamel surface, the prism sheath vanishes between the parallel-oriented prisms, so that these merge into a prismless outer enamel zone, a feature observed in a number of Mammalian taxa. In other areas, the enamel contains large vacuities, probably the result of diagenesis.

 

Scanning electron microscope images of vertical section of outer zone of NUFV 2092B (A) and (B), and uncoated tangential sections of NUFV 2092B (C) and Yukon Government (YG) 514.12 (D), rhinocerotoid enamel from [26]. In (A) the region outlined by white square is magnified in (B). OES, outer enamel surface. (C) Magnified uncoated tangential section of NUFV 2092E under a light microscope, compared to (D) uncoated tangential section of YG514.12, enamel of a Miocene Rhinocerotoid from the Yukon, Canada under a light microscope. Eberle et al. (2020).

In summary, the analysis of NUFV 2092B and 2092E in horizontal, tangential, and vertical sections at both low and high magnification indicates that the enamel is characterized by elongate, vertical bodies extending from near the enamel-dentine junction towards the outer enamel surface that are made up of steeply-angled prisms that decussate with adjacent bodies. The inner region of the middle enamel zone contains nested chevron or treelike structures that are evident in horizontal and tangential sections, whereas in the outer region, the vertical bands become broader and the nested chevron structures are lost. An outer zone of radial enamel or prismless outer enamel zone occurs next to the outer enamel surface.

The enamel microstructure that occurs in NUFV 2092B and 2092E is comparable to that of the Pantodont Coryphodon. Coined 'Coryphodon-enamel', this enamel type is characterised by vertical or oblique structures that in tangential section appear as light-colored bands of nested chevrons or treelike structures separated from one another by similar, though narrower, dark-colored bands. The difference in width between the light and dark stripes when light is reflected from one direction indicates that the prism orientation is not symmetrical. Also like Coryphodon-enamel (although not restricted to it), NUFV 2092B and 2092E have an outermost zone of radial enamel, as well as rounded prisms that open to one side and are surrounded by interprismatic matrix that is nearly parallel to the prisms. Given the suite of characters shared with Coryphodon-enamel, but predominantly the vertical bodies that manifest as lines of nested chevrons or treelike structures in tangential view, NUFV 2092B and 2092E possess Coryphodon-enamel. However, does Coryphodon-enamel occur in any of the other large Mammals known from the Arctic localities?

In the Canadian Arctic, Rhinocerotoids are known from early Miocene sediments of the Haughton Formation on Devon Island and from the Yukon. Rhinocerotoids have vertical Hunter-Schreger bands in their tooth enamel that look somewhat like the vertical elements in Coryphodon-enamel. However, the vertical bands in Rhinocerotoid enamel contrast with those in Coryphodon-enamel in that they are of consistent thickness and spacing from one another and separated by thin transitional zones of 2–3 prisms wide. In tangential section, Rhinocerotoid enamel shows light and dark vertical lines that bifurcate in a regular pattern and lack the nested chevron or treelike structures in Coryphodon-enamel.

Although not nearly as regular in pattern as the vertical Hunter-Schreger bands in Rhinocerotoids, Coryphodon-enamel nevertheless cannot be considered irregular enamel. This enamel type, which occurs in Proboscideans (Elephants and their extinct relatives) and some Rodents, is characterised by prisms that twist irregularly in bundles or as single prisms around each other, and bundles of prisms show a range of angles and attitudes with no consistent pattern.

The Brontotheres cf. Eotitanops and Palaeosyops are documented from Early-Middle Eocene rocks of the Margaret Formation on Ellesmere Island, and tooth fragments from a larger, younger Brontothere were recovered from middle Eocene strata of the Buchanan Lake Formation on nearby Axel Heiberg Island. However, Brontothere tooth enamel differs from Coryphodon-enamel in having U-shaped Hunter-Schreger bands, an intermediate condition between the horizontal Hunter-Schreger bands found in most large Mammals and the vertical Hunter-Schreger bands of Rhinocerotoids. Tapiroids occur at Early Eocene localities in the Margaret Formation. However, Tapiroids have horizontal to curved Hunter-Schreger bands.

The nested chevron pattern seen in the tangential section of Coryphodon-enamel is reminiscent of the zigzag Hunter-Schreger bands found in advanced Carnivorans, particularly Crocuta crocuta (Hyaena) that correlate with ossiphagous (or bone-eating) habits. However, the enamel of Crocuta crocuta differs from Coryphodon-enamel in that the vertical structures show a symmetrical pattern when illuminated from opposing directions in tangential section, and the vertical light and dark bands are of similar thickness.

Several Carnivoromorpha are known from the Margaret Formation, but their enamel shows significant differences from Coryphodon-enamel. Miacis, cf. Vulpavus, and Viverravus are small-bodied members of Carnivoromorpha whose tooth enamel is much thinner (and smoother) than that of NUFV 2092B and 2092E. Further, the tooth enamel of these early Eocene Carnivores contains undulating Hunter-Schreger bands, which are essentially horizontal, slightly wavy Hunter-Schreger bands. The Oxyaenid Palaeonictis and Mesonychid Pachyaena are the largest Carnivores in the Margaret Formation, although their fossils are rare, with each taxon represented by a single fossil in the Arctic. The enamel of these taxa has undulating Hunter-Schreger bands in the lower half of the tooth that transitions into zigzag Hunter-Schreger bands in the upper one-half to one-third of the tooth. Coryphodon-enamel altogether lacks undulating Hunter-Schreger bands. In addition to its namesake, Coryphodon-enamel is known to occur in middle Eocene Uintatherium and late Eocene Entelodon, neither of which is known from the early Eocene nor from the polar region. Therefore, it is unlikely that the Coryphodon-enamel reported here from the Strathcona Fiord Fossil Forest belongs to any other Mammal besides Coryphodon.

The tooth enamel fragments reported here, along with some poorly preserved bone fragments, thus far are the only documented vertebrate fossils from the Strathcona Fiord Fossil Forest. However, Coryphodon fossils occur elsewhere in the Margaret Formation on Ellesmere Island, so its presence at the Strathcona Fiord Fossil Forest is not surprising. What is novel in Eberle et al.'s study is the way in which they identify the fossils NUFV 2092B and 2092E to Coryphodon by way of their enamel microstructure. Complete Mammalian teeth and jaws are morphologically diagnostic and readily identified to genus and even species. However, in the Arctic, Eocene Vertebrate fossils are rare, and many are fragmentary. Eberle et al. provide an example of how enamel microstructure can be used to identify the Mammal.

The presence of Coryphodon suggests that the strata containing the Strathcona Fiord Fossil Forest are temporally correlative with the early Eocene (Wasatchian) fossil-bearing strata of the Margaret Formation approximately 25 km further north at Bay Fiord, a conclusion reached independently by lithologic correlation. At Bay Fiord, Perissodactyls, Hyaenodontid Creodonts, Miacis, and cf. Vulpavus, all of which first appear at mid-latitudes in the Wasatchian, as well as the Wasatchian index taxon Pachyaena and the archaic Ungulate Anacodon, which last appears in the Wasatchian, occur in the lower faunal level of the Margaret Formation. Although Coryphodon occurs at early middle Eocene (Bridgerian) localities at mid-latitudes, it is restricted to the early Eocene (Wasatchian) faunal assemblage in the Arctic. The strata containing the Strathcona Fiord Fossil Forest were initially mapped as the Late Paleocene Mount Lawson Formation of the Eureka Sound Group. However, Eberle et al.'s study indicates that they should be re-mapped as the Margaret Formation on the basis of lithology, palaeoenvironmental interpretations, and the presence of Coryphodon.

Vertical elements such as those found in the enamel of the Carnivore Crocuta (Hyaena) and Entelodonts are hypothesised to be an adaptation to deal with high stresses during mastication/ Crocuta is carnivorous and ossiphagous, whereas Entelodonts have been interpreted as omnivores and Pig-like in their diet, ingesting a variety of food items, including plants, meat, and bones. In contrast, Coryphodon, based on its transverse shearing lophs and carbon isotope values, is interpreted as an herbivore, and probably semiaquatic. Based on its oxygen and carbon isotope values, Coryphodon is inferred to be a year-round resident above the Arctic Circle and therefore experienced months of darkness and the shutdown of photosynthesis during the polar winter. Seasonal isotopic variations, and specifically high winter proportional carbon¹³ values in the enamel of Coryphodon teeth from Ellesmere Island, suggest a varied diet during the dark winter that probably included wood, leaf litter, and evergreen Conifers. The presence of vertical elements in the enamel microstructure of Coryphodon may have pre-adapted these large Mammals to ingesting tough, poorer quality food items during the long dark winters above the Arctic Circle. This could partly explain why Coryphodon is the most abundant herbivore in the Eocene Arctic.

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Bhavania annandalei: The identity and distribution of a a Hillstream Loach endemic to the Western Ghats of India.

The Hillstream Loach, Bhavania annandalei, was described by Sunda Lal Hora in 1920 from Tenmalai, in what was then Travancore State (current day southern Kerala), and suggested that the species occurs throughout the southern Western Ghats in the Nilgiris, Malabar, and Travancore. Hora diagnosed Bhavania annandalei from its only known congener, Bhavania australis by a combination of characters; the most prominent of which included a broad snout (rather than a pointed one), interrupted lower lip (as opposed to a continuous one), caudal-lobes equal (rather than a longer lower lobe), and presence of a pair of papillae on the lower lip (rather than thier absence). Hora’s description of Bhavania annandalei was however, based on a single adult female specimen collected by Thomas Nelson Annandale from Travancore, Kerala. Though, Hora (1920) seemed to have access to additional juvenile specimens collected by Captain Robert Sewell from the Nilgiris (Cherambadi) and Wayanad (Nellimunda, Mananthavady, and near Vythiri), he did not examine them or provide other details. Subsequently, Hora extended the distribution of the species to Mysore, based on four specimens collected by M.S. Bhimachar from a stream between Kottigehar and Balehonnur (in what was then Mysore State, i.e. the current day Tunga River System in Karnataka). No details of the specimens were provided. 

In his review on ‘Homalopterid fishes from Peninsular India’, Hora synonymized Bhavania annandalei with Bhavania australis, after examining specimens from throughout its distribution range including Kallar/South Travancore (current day Vamanapuram River, Kerala); Pampadumpara/North Travancore (current day Periyar River, Kerala); Sethumadai Hills/Mysore (current day Anamalai hills near Pollachi, Tamil Nadu); and Kottigehar/Mysore (current day Tunga River, Karnataka), and realising that his description of Bhavania annandalei was based mainly on immature specimens. This synonymy was subsequently adopted by Ambet Gopalan Kutty Menon in his review of the Homalopterid Loaches of India, but without examining the type (or fresh topotypes) of Bhavania annandalei, or the topotypes of Bhavania australis. Later workers followed this synonymy and considered Bhavania to be monotypic. ‘Bhavania arunachalensis’, described in 2007 from Naodhing drainage in Arunachal Pradesh, is considered to be a species of doubtful identity and uncertain placement, and is most likely a species of the genus Balitora. 

Given their hill-stream adaptations (widespread paired fins, flattened ventral surfaces with body suckers and rasping mouths on their ventral surface allowing them to firmly grasp rock or gravel surfaces necessary in the mountain torrents), and the fact that the type locality of Bhavania annandalei (Tenmalai) and Bhavania australis (Walayar) are at least 300 km apart and separated by two significant biogeographic barriers - the Palghat Gap and the Shencottah Gap, it is highly unlikely that the two are conspecific.

In a paper published in the journal Threatened Taxa on 26 July 2020, Remya Sundar of the Center for Aquatic Resource Management and Conservation at the Kerala University of Fisheries and Ocean Studies, VK Anoop and Arya Sidharthan of the School of Ocean Science and Technology, also at the Kerala University of Fisheries and Ocean Studies, Neelesh Dahanukar of the Indian Institute of Science Education and Research and the Zoo Outreach Organization, and Rajeev Raghavan, also of the Center for Aquatic Resource Management and Conservation and School of Ocean Science and Technology, and of the Department of Fisheries Resource Management, at the Kerala University of Fisheries and Ocean Studies, present a re-description of Bhavania annandalei, based upon newly collected specimens.

Six specimens of putative topotypic Bhavania annandalei were collected from Palaruvi falls at Tenmala (Kallada River), Kerala, and six specimens of putative topotypic Bhavania australis were collected from near the Kavarakund falls, upstream of Malampuzha Reservoir, Kerala, India. Samples were collected using a hand net/scoop net during early morning hours, fixed in 10% formalin and transferred to 70% ethanol for permanent voucher storage in the museum collections of the Kerala University of Fisheries and Ocean Studies. Gill tissues were obtained from fresh specimens and preserved in absolute ethanol.

 

Collection localities of putative topotyes of Bhavania annandalei and Bhavania australis. Sundar et al. (2020).

Bhavania annandalei is distinguished from its only known congener Bhavania australis by a combination of characters: low density and sparsely distributed tubercles on dorsal surface of head, especially on operculum, (whereas Bhavania australis has a high density of tubercles on dorsal surface of head and operculum); gape of mouth comparatively farther from snout tip, as a result the rostral barbels reaching anterior border of upper lip, (in Bhavania australis the gape of mouth is closer to snout tip, and rostral barbels reaching posterior border of upper lip); rostral flaps between the rostral barbels fleshier than in Bhavania australis; fewer post-dorsal scales (34–36 compared to 38–41); fewer scales above the lateral line (11–12 compated to 14–15); and caudal peduncle stout with its depth to width ratio 1.8–2.3 (Bhavania australis has a laterally compressed caudal peduncle with depth to width ratio 2.8–3.6).

 

Putative topotypes: (a) Bhavania annandalei; (b) Bhavania australis in life (specimens not preserved). Sundar et al. (2020).

The body of Bhavania annandalei is elongate, dorso-ventrally depressed anteriorly, laterally compressed posteriorly; dorsal profile convex, deepest at dorsal-fin origin. Body wider than its depth at dorsal-fin origin, deeper than wide at anus. Head small, rounded, less than one-fourth of standard length; depressed, longer than broad, with minute sparsely distributed indistinct tubercles on dorsal surface of head. Eyes small, dorso-laterally positioned, not visible from underside of head. Snout pointed in lateral view, round in dorsal view. Nostrils positioned dorsally, closer to anterior border of eye than to snout tip, anterior nostril situated inside a skin flap covering the posterior nostrils. Mouth inferior. Lips fleshy. Gape of mouth less than three times maximum head width. Barbels three pairs, two rostral: outer rostral barbels shorter than inner ones; one pair of maxillary barbels, situated slightly anterior to the angle of mouth. Three fleshy rostral flaps interspaced between rostral barbels. Gill opening small, restricted above the base of the pectoral fin.

 

Dorsal, lateral, and ventral images of putative topotypes: (a) Bhavania annandalei; (b) Bhavania australis. Sundar et al. (2020).

Body with scales except chest and belly. Lateral line complete, with 68–72 small scales. Caudal peduncle slender, its length almost three times its depth. Dorsalfin originating slightly behind the pelvic-fin origin, closer to tip of snout than to caudal-fin base; with two unbranched, followed by seven branched and a simple ray. Pectoral fin elongated, longer than head, with six unbranched, followed by 10 branched and a simple ray. Pelvic-fin length almost equal to head length; fin origin closer to snout tip than to end of caudal peduncle, its posterior end not reaching anus, with two unbranched and eight branched rays. Anal fin with two unbranched and five branched rays. Caudal fin forked, with 19 principal rays. 

Dorsal and ventral view of head: (a), (c) Bhavania annandalei; (b), (d) Bhavania australis. Sundar et al. (2020).

In life Bhavania annandalei is body is chestnut brown on dorsal and lateral sides, creamish-white on chest and belly; 3–4 prominent broad dark brown ventral bands; two broad ventral bands on the dorsalfin base. There are three black-coloured bands on the dorsal fin, 6–7 bands on the pectoral, three bands on the pelvic, 1–2 bands on the anal, and four bands across the caudal fin.

Morphometric analysis is a tool used by palaeontologists, archaeologists, anthropologists and forensic pathologists to analyse and compare specimens. It relies on taking numerous measurements of an object such as a bone or shell, and comparing both these measurements and ratios between measurements to those obtained from other specimens in order to establish relationships between them. 

Morphometric measurements were taken for 37 characters (measured to the nearest 0.1mm using digital calliper) and meristic values were determined for 10 characters using a stereo-zoom microscope. For meristic counts, values in parenthesis after the count respresent its frequency. For statistical analysis of morphometric data, subunits of body were taken as percentage of standard length and subunits of head were taken as percentage of head length. Principal component analysis was performed to check whether the two species formed distinct clusters in multivariate space using correlation matrix. Null hypothesis that the clusters are not significantly different from each other was tested using analysis of similarities employing Euclidian distances and 9999 permutations. Statistical analysis was performed in PAST 4.02.

Using size-adjusted characters, the two species clustered separately on the first two principal component analysis axes. The clusters were significantly different from each other, indicating that the species formed distinct clusters in multivariate space. While lengthlength relationships for most characters showed similar trends for both the species, there were two relationships that showed marked differences. Length-length relationship between caudal peduncle depth and width suggested that width increased rapidly with increasing depth in the case of Bhavania annandalei compared to Bhavania australis. Similarly, length-length relationship between head length and head depth at nape suggested that head depth increased rapidly with increasing head length in the case of Bhavania annandalei compared to Bhavania australis.

Genetic sequences of mitochondrial partial cytochrome oxidase subunit 1 (cox1) of topotypic Bhavania annandalei and Bhavania australis were obtained from the collected specimens. Additional sequences were downloaded from GenBank database. Gene sequences were aligned using MUSCLE and raw genetic distance was estimated using MEGA 7. Data were partitioned into three codon positions of cox1 gene. Partition analysis (a statistical method) and ModelFinder were used to find the right partitioning scheme and nucleotide substitution model for the partition scheme employing minimum Bayesian information criterion. Maximum likelihood analysis was performed in IQ Tree with best partition scheme and ultrafast bootstrap support for 1000 iterations. Phylogenetic tree was edited in FigTree v1.4.2.

Partition analysis and model selection identified separate nucleotide substitution models for all three codon positions, TNe+I for first codon, F81+F for second codon, TN+F+G4 for third codon position of cox1 gene. Maximum likelihood phylogenetic tree based on best partition scheme and model selection recovered Bhavania annandalei and Bhavania australis as a clade sister to Southeast Asian congeners of Balitoridae. Topotypic Bhavania annandalei (MT002520) differed from topotypic Bhavania australis (MT002518) with a raw genetic distance of 6.4% in the cox1 gene.

 

Maximum likelihood phylogenetic tree based on mitochondrial cytochrome oxidase subunit 1 gene using best partition scheme and model selection (lnL of consensus tree = -2631.97). Indoreonectes keralensis (Nemacheilidae) is used as an outgroup. Values along the nodes are percentage bootstraps based on 1,000 iterations. Sundar et al. (2020).

Bhavania annandalei is known with certainty from the Kallada, Vamanapuram, and Neyyar river systems in southern Kerala, India. These river systems drain the western slopes of the Agasthyamalai Hill ranges, south of the Shencottah Gap. It is highly likely that the species also occurs on the eastern slopes of the Agasthyamalai Hills particularly in the Tambaraparini River system in Tamil Nadu, but detailed surveys and voucher specimens are required to confirm this. In this context, Sundar et al. believe that previous records of Bhavania australis from several tributaries of the Tambaraparini, Manimuthar, and Chittar draining the eastern slopes of the Agasthyamalai, could most likely represent Bhavania annandalei.

The density of chromatophores in Bhavania is likely to be dependent on the micro-habitat as well as the colour and type of substratum it inhabits. Other ecological factors that may influence body colour are forest/canopy cover, intensity of light, turbidity, water flow and water temperature. This is reflected in the different body colours shown by the two species in different habitats and locations, an observation which was also made by Sunda Lal Hora. 

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