Oxynoemacheilus kottelati: A new species of Stone Loach from the Aegean drainage of Anatolia.

Stone Loaches of the genus Oxynoemacheilus are found across the Eastern Mediterranean, the southern Caucasus, Anatolia, Mesopotamia, and Central Iran. To date, 67 species have been assigned to the genus, of which are found in Turkish inland waters, and 36 entirely endemic to the country. Sixteen species are found within the Tigris and Euphrates basins, 14 within rivers and streams draining into the Mediterranean, six in rivers and streams draining into the Black Sea, four in rivers and streams draining into the Caspian, two species within the Konya Basin, two within the Marmara Basin, and one within the Van Basin. 

In a paper published in the journal Zoosystematics and Evolution on 9 May 2024, Davut Turan of the Faculty of Fisheries at Recep Tayyip Erdoğan University, Sadi̇ Aksu of the Vocational School of Health Services at Eskişehir Osmangazi University, Sali̇m Serkan Güçlü of the Faculty of Eğirdir Fisheries at Isparta University of Applied Sciences, and Gökhan Kalaycı, also of the Faculty of Fisheries at Recep Tayyip Erdoğan University, describe a new species of Oxynoemacheilus from streams in the Aegean drainage of Anatolia.

The new species is named Oxynoemacheilus kottelati, in honour of the Swiss ichthyologist Maurice Kottelat, for his contributions to our understanding of the world's Fish fauna. The species is described from a series of Fish collected from the Havran and Karınca streams in Balıkesir Province, Turkey, in October 2023.

Oxynoemacheilus kottelati FFR 15655, (a), (b) Holotype, male, 47 mm; FFR 15656; (c) Paratype, female, 49 mm; Türkiye, Balıkesir Province, Havran Stream. Turan et al. (2024).

Specimens of Oxynoemacheilus kottelati range from 35 to 54 mm in length, with a deep body, laterally compressed at the base of the tail. They have a marbled brownish pattern on their flanks and dorsal surface, but are white on the underside. 

Oxynoemacheilus kottelati, FFR 15657, paratypes: (a) male, 47 mm; (b)female, 46 mm; (c) male, 45 mm; Havran Stream; FFR 15656; (d) female, 48 mm; Karınca Stream; Türkiye, Balıkesir Province. Turan et al. (2024).

See also...

Assessing the impact of predation on birth size in marine Snakes.

Moving from one environment to another exposes organisms to new selective pressures on life histories, and where multiple organisms from related lineages make the same transition, it presents an opportunity for biologists to analyse these pressures. For example, Squamates (Snakes and Lizards) which migrate from warm environments to cooler ones frequently switch from egg-laying to bearing live young, while Birds making the same transition tend to produce smaller clutches of eggs.

Birth size is considered to be a fundamental life-history trait, subject to a number of evolutionary pressures. Where intraspecific competition is low, smaller birth sizes are often a result, as offspring survival is not dependent on size at birth. Conversely, larger birth size can be driven by a number of factors, for example a lack of small prey can drive up birth size in species where the young must hunt for themselves, as only larger neonates are able to capture enough prey to survive. 

The shift from a terrestrial habitat to a marine one presents organisms with a variety of different challenges, including thermal regimes, oxygen availability, light levels, ocean currents, types of predators, prey, competitors and pathogens. Nevertheless, the marine environment clearly presents opportunities for terrestrial Tetrapods, with numerous lineages of Mammals, Reptiles, and even Birds having made the transition. Elapid (Front-fanged) Snakes have made this transition at least three times, with the Sea Kraits, Laticaudinae, having split from terrestrial relatives in Asia about 16 million years ago, while at least two lineages within the Australian subfamily Hydrophiinae (together referred to as Sea Snakes) switched to a marine habit more recently. The three lineages show convergent evolution for a number of traits, including the development of laterally compressed bodies with paddle-like tails, the appearance of salt-excreting glands, and common life-history traits. A fourth group of (non-Elapid) Snakes, the Acrochordidae, are semi-aquatic, and often semi-marine in habit, and show some of these traits.

Marine Snakes typically produce fewer young than terrestrial Snakes, which has been linked to a need for gravid females to retain a hydrodynamic shape. Nevertheless, the offspring are typically larger at birth than those of their terrestrial relatives, which would seem to work against this.

In a paper published in the journal Royal Society Open Science on 13 December 2023, Richard Shine of the School of Natural Sciences at Macquarie University, Shai Meiri of the School of Zoology and Steinhardt Museum of Natural History at Tel-Aviv University, Terri Shine and Gregory Brown, also of the School of Natural Sciences at Macquarie University, and Claire Goiran of LabEx Corail and  Institut de sciences exactes et appliquées at the Université de la Nouvelle-Calédonie, examine the possibility that size-selective predation on young Snakes could be the driver of increased neonatal size in Marine Snakes.

Smaller terrestrial Snakes are known to be vulnerable to a wider range of predators than larger Snakes, with many predators targeting smaller Snakes while actively avoiding larger ones. However, predation rates on smaller Snakes can be lower than on larger individuals, due to the ability of small Snakes to remain inactive in well-hidden retreats.

Marine Snakes are less able to do this, as they must ascend to the surface to breath. This means that Snakes must leave their protective shelters and cross open water, where they are vulnerable to predation, several times per day. Predation of Snakes by large Fish during these crossings is well-documented, supporting the hypothesis that this is a risky endeavour for marine Snakes.

In order to test the hypothesis, Shine et al. first examined records of birth sizes in both marine and terrestrial Snakes, to confirm that the perceived trend was in fact real, then carried out experimental trials with model Snakes of different sizes to see if smaller Snakes were in fact more vulnerable to predation.

Shine et al. obtained data on hatchling and neonate sizes (Snakes can lay eggs or bear live young, but this does not appear to affect infant size much) and snout-vent lengths of adult females of 166 species of terrestrial, semi-aquatic, and marine Snakes, from published literature and the collection of the Steinhardt Museum. Semi-aquatic Snakes were found to produce slightly smaller offspring than terrestrial Snakes on average. However, the sample size for these Snakes was very small, and the subject was not investigated further. The adult snout-vent length for female Snakes in the study averaged at 800 mm, with the offspring of terrestrial Snakes having an average length of 200 mm, and the average length of new-born marine Snakes being 300 mm. 

Based upon this, Shine et al. hypothesised that a 200 mm Snake would be at significantly higher risk of predation in a typical marine Snake environment than a 300 mm Snake. To test this, an experiment was devised in which commercially available fibreglass fishing lures designed to resemble Snakes had their hooks removed and additional weights added to ensure they retained negative buoyancy, and were painted black to resemble the most common colour morph of the locally abundant Turtlehead Sea Snake, Emydocephalus  annulatus. These were then dragged by a snorkeler, Claire Goiran, over Coral reefs off the island of Ile aux Canards in New Caledonia, while a second snorkeler, Richard Shine, followed and recorded the reaction of large predatory Fish to the lures. 

A Camouflage Grouper, Epinephelus polyphekadion, following a black Snake-shaped lure, immediately prior to launching an attack. Teri Shine in Shine et al. (2023).

During 47 trials, Shine et al. recorded 114 responses. These included 38 attacks, and 76 encounters in which Fish followed the lure but did not attack. The size of the lure did not appear to influence whether or not Fish followed it, but they were significantly more likely to attack the smaller lures. Similarly, larger Fish were more likely to attack the lures, while smaller Fish tended to break off following without attacking. Thus, the majority of attacks were by large Fish on small lures.

Multiple lineages of Snakes which have invaded marine habitats have had an increase in neonatal size, combined with a reduced brood size (which are probably connected). Shine et al.'s study suggests that increased predation on smaller Snakes is a plausible explanation for this (although they stress that the results of their study cannot be taken as an absolute proof).

Shine et al. also note that larger Snakes are more likely to survive attacks by Fish, noting that two incidents of Snakes being seized by Fish and then released because the Fish was unable to overpower the Snake have been recorded on reefs close to their study area. In one of these incidents a Chocolate Grouper, Cephalopholis  boenak, unsuccessfully attacked a Turtlehead Sea Snake, Emydocephalus  annulatus, and in the other a Reef Stonefish, Synanceia verrucosa, was forced to break off an attack on a Blue Lipped Sea Krait, Laticauda  laticaudata, suggesting that larger size may present an advantage to young Snakes in surviving attacks, even if Fish do not discriminate against larger Snakes when choosing whether to attack.

A Reef Stonefish, Synanceia verrucosa, making an unsuccessful attack on a Blue Lipped Sea Krait, Laticauda  laticaudata, off the coast of Ile aux Canards in October 2022. Richard Fish/iNaturalist.

Predation is often cited as a likely cause of evolutionary pressure, influencing traits such as size and colouration. However, direct evidence of such impacts is difficult to gather accurate information on this unless predation rates are extremely high. Furthermore, it is difficult to design experiments looking at predatory behaviour for larger Animals without running into ethical and logistical constraints.

Predation is not the only driver of larger size in young marine Snakes which has been made, but it does seem to be the best supported by the available evidence. 

It has been suggested that larger size may provide an advantage when swimming, with smaller Snakes potentially being less efficient swimmers, using more energy to go slower. However, research into Sea Kraits has shown that smaller individuals have a higher swimming speed relative to crawling speed than larger individuals, suggesting that in these marine Snakes smaller size produces an advantage when swimming. 

Another possibility is that larger size in neonatal marine Snakes might be driven by prey size, with a shortage of suitable prey capturable by smaller Snakes creating a need for infant Snakes to be as large as possible. However, many Sea Snakes feed on smaller prey, notably members of the genus Emydocephalus are specialist feeders on Fish eggs, and several members of the genus Hydrophis have miniaturized heads and slender forebodies that enable them to penetrate the burrows of the small Fish upon which they prey.

Another possibility is that intraspecific competition drives larger size in young marine Snakes, with larger individuals excluding smaller individuals from better territories or access to prey. However, aggressive behaviour between members of the same species has never been observed in marine Snakes, making this unlikely.

Finally, larger size can act as a buffer against temperature changes, with larger bodies taking longer to either warm up or cool down that smaller bodies, thereby giving the Snakes more time to react to changes in conditions. However, marine environments offer much more protection against such temperature fluctuations than terrestrial ones, due to the high conductivity of water, making this highly unlikely as a driver of size in marine Snakes.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.

Nemacheilus pullus: A new species of Stone Loach from central Laos.

Stone Loaches, Nemacheilidae, are freshwater Cypriniform Fish found throughout Eurasia, with one genus occurring in Ethiopia. They favour fast moving stretches of small streams, but are occasionally found in larger rivers, and even caves. The group currently contains about valid 790 species in 53 genera, with new species being described on a regular basis, particularly from Southeast Asia. The genus Nemacheilus currently includes 36 species from the Chao Phraya, Mae Khlong, and Mekong river drainages, the Malay Peninsula, and the islands of Sumatra, Java and Borneo. Members of this genus tend to be found in streams and rivers with slow to moderate flows and sand, gravel, or pebble bottoms.

In a paper published in the Raffles Bulletin of Zoology on 20 February 2023, Maurice Kottelat of the Lee KongChian Natural History Museum at the National University of Singapore, describes a new species of Nemacheilus from central Laos.

The new species is named Nemacheilus pullus, where 'pullus' is intended to mean dark yellow to blackish. The species is described from populations living in the Nam Ngiep and Nam Xan watersheds of the the Mekong drainage in central Laos, which were previously assigned to the species Nemacheilus platiceps.

Nemacheilus pullus, Laos: Mekong drainage: Nam Ngiep watershed; (a) CMK 27518, paratype, male, 37.7 mm; (b) MHNG 2787.091, holotype, male, 41.5 mm; (c) CMK 27518, paratype, female, 64.1 mm. Note that in b the specimen is slightly tilted laterally and the eye appears more distant from the dorsal profile than in reality. Kottelat (2023).

Nemacheilus pullus shares with Nemacheilus platiceps an incomplete lateral line, whereas in almost all other members of the genus the lateral line is complete. However Nemacheilus pullus lacks the clear flank bars of Nemacheilus platiceps, instead being a plain yellowish grey in colour (juveniles, and some adult females, do have faint bars, but these are much less clear than in Nemacheilus platiceps). 

Nemacheilus platiceps; (a) CMK 21392, 27.8 mm; Laos: Mekong drainage: Xe Kong watershed; (b)–(d) CMK 7927, Vietnam: Dong Nai drainage, 36.2 mm, (b) reversed) 40.8 mm, 54.4 mm, (d) reversed; and (e) NRM 15095, holotype, 40.1 mm; Vietnam Dong Nai drainage (reversed). Kottelat (2023).

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter. 

Sillago muktijoddhai & Sillago mengjialensis: Two new species of Sillago from Bangladesh.

Sillagos, Sillago spp., are inshore Perciform Fish widespread in the IndoPacific region. They form an important part of many food webs, feeding on Crustaceans and Molluscs in coastal waters or estuarine areas of rivers with open sandflats and muddy substrates, and in turn being fed upon by larger Fish, Marine Mammals, and Seabirds. Understanding the population structure of these Fish has proven difficult, as the genus contains a large number of very similar-appearing species, often identifiable only by the structure of their swim bladders, with the recent application of genetic profiling to the group suggesting that even this is not reliable, and that the group may contain more cryptic species (species which cannot easily be told apart by physical examination) than previously realised.

In a paper published in the journal Fishes on 18 April 2022, Shilpi Saha of the Fisheries College at the Ocean University of China, and the Department of Zoology at Jagannath University, Na Song and Zhengsen Yu, also of the Fisheries College at the Ocean University of China, Mohammad Abdul Baki, also of the Department of Zoology at Jagannath University, Roland McKay of the Chillagoe Museum, Jianguang Qin of the School of Biological Sciences at Flinders University, and Tianxiang Gao of the Fishery College at the Zhejiang Ocean University, describe two new species of Sillago from Bangladesh.

The new species are described from specimens obtained from fishermen at locations in Cox’s Bazar, Sundarbans, Patharghata, Maheshkhali and Saint Martin’s Island. These Fish are typically caught using beach seine nets in this area.

The first new species described is named Sillago muktijoddhai, were 'muktijoddhai' refers to the muktijoddha freedom fighters who fought for Bangladesh's independence from Pakistan from 1971 to 1979. 

Sillago muktijoddhai is elongated in shape, slightly steep anteriorly, and tubular posteriorly. The upper jaw is slightly protracted and crescentic, with minute villiform teeth on both jaws in one row. The back edge of the preopercle is slightly denticulated, and the opercle has one fragile spine posterodorsally. Gill rakers on the first arch are pointed and gradually become short towards the end. The body is covered with moderate-sized, overlapping ctenoid scales. The cheek scales cycloid, arranged in two rows.

There are two distinctly separate dorsal fins. The first dorsal fin is higher than the second, originating above the pectoral-fin base; its second spine is the longest, and the length of the succeeding spines decrease gradually. The base of the second dorsal fin is long, beginning at the midbody and not reaching the caudal-fin base when depressed. The anal fin originates slightly posterior to the anus, not reaching the caudal-fin base when depressed. The two disconnected pelvic fins are wide, roughly three-cornered, and shorter than the pectoral fin.

The body of Sillago muktijoddhai is greenish dorsally and light yellowish ventrally with black dots on the side below the lateral line. The cheek has black dots gathered on the anteroventral part of the eyes. The dorsal fins are hyaline, and small dark spots exist on the fin membrane, but those on the second dorsal fin form two or three distinct rows. The pectoral and pelvic fins are light yellowish. The anal fin is light yellowish with black spots. The caudal fin is light yellowish, dusky, and with a white edge; the lobes are truncated or emarginated.

Sillago muktijoddhai from the Bay of Bengal, Bangladesh. Saha et al. (2022).

The second new species is named Sillago mengjialensis, where 'mengjialensis' means 'from Mèngjiālā', where Mèngjiālā is the Chinese name for Bengal, in reference to the fact that the species was discovered as part of a collaborative project between scientists from China and Bangladesh.

The body of Sillago mengjialensis is elongated, somewhat conical anteriorly, and cylindric posteriorly. The back edge of the preopercle is slightly toothed. The opercle only has one weak spine posterodorsally. The gill rakers on the first arch are pointed and gradually become small towards the end. The body is covered with moderate-sized, overlapping ctenoid scales. The cheek scales are cycloid, arranged in two rows.

There are two disconnected dorsal fins. The first dorsal fin is higher than the second, originating above the pectoral fin base; its second spine is the longest, and the length of the succeeding spines decreases gradually. The base of the second dorsal fin is long, beginning at the midbody, and not reaching the caudal-fin base when depressed. The anal fin originates slightly posterior to the anus, not reaching the caudal-fin base when depressed. Two disconnected pelvic fins are large, roughly trigonal in shape, and smaller than the pectoral fin.

The body of Sillago mengjialensis is light olive greenish dorsally and silver ventrally with black spots on the sides below the lateral line. The cheek has black spots gathered on the anteroventral part of the eyes. The dorsal fins are hyaline with small dark spots on the fin membrane adjacent to the ray. The pectoral and pelvic fins are light yellowish. The anal fin is light yellowish to whitish with black dots. The caudal fin light yellowish, dusky, and has a white margin; the lobes are truncated or emarginated.

 

Sillago mengjialensis from the Bay of Bengal, Bangladesh. Saha et al. (2022).

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.

 

Neopagetopsis ionah: Vast nesting colony of Jonah's Icefish found in the Weddell Sea, Antarctica.

Crocodile Icefish, Channichtyidae, are highly specialised Perciform Fish found in the waters around Antarctica. They are sometimes known as White-blooded Icefish, as they lack haemoglobin; the cold waters around Antarctica being so saturated in oxygen that these Fish no not need a specialised means to transport it to their tissues (water is able to retain more free oxygen at lower temperatures). These Fish are known to nest in colonies, with a few tens of Fish typically building their nests together in a favoured spot.

In a paper published in the journal Current Biology on 13 January 2022, Autun Purser and Laura Hehemann of the Alfred Wegener Institute at the Helmholtz Centre for Polar and Marine Research, Lilian Boehringer, also of the Alfred Wegener Institute, and of Universität Bremen, Sandra Tippenhauer again of the Alfred Wegener Institute, Mia Wege of the Alfred Wegener Institute and the Mammal Research Institute at the University of Pretoria, Horst Bornemann, Santiago Pineda-Metz, Clara Flintrop, Florian Koch, and Hartmut Hellmer, again of the Alfred Wegener Institute, Patricia Burkhardt-Holm of the Programme Man-Society-Environment at the University of Basel, Markus Janout, again of the Alfred Wegener Institute, Ellen Werner of the HafenCity University Hamburg, Barbara Glemser of Universität Bremen and the Max Planck Institute for Marine Microbiology, Jenna Balaguer, also of the Alfred Wegener Institute, Andreas Rogge of the Alfred Wegener Institute and the Institute for Ecosystem Research at Kiel University, Moritz Holtappels, once again of the Alfred Wegener Institute, and Frank Wenzhoefer of the Alfred Wegener Institute, the Max Planck Institute for Marine Microbiology, and the Department of Biology at the University of Southern Denmark, describe a vast colony of Channichtyida Icefish numbering tens of thousands of nests, discovered on the eastern flank of the Filchner Trough within the Weddell Sea.

The colony is of Jonah's Icefish, Neopagetopsis ionah, a benthopelagic species (species that lives just above thes seafloor) known from the Weddell Sea, Kapp Norvegica, Halley Bay, Vahsel Bay, the Antarctic Peninsula, and the Ross Sea, with a pelagic juvenile stage (juvenile stage that lives in the water column), which has been reported from the Weddell Sea, South Shetland Islands, and McMurdo Sound. Purser et al. report a colony of about 16 160 Icefish covering an area of about 45 600 m², which was discovered by the Ocean Floor Observation and Bathymetry System, towed camera platform deployed by the RV Polarstern.

 

Seafloor images of the most expansive Icefish breeding colony discovered to date (A) Left: Neopagetopsis ionah in an active Fish nest on the eastern flank of the Filchner Trough, 497-m depth. Each
15-cm-deep nest has been shaped by removing the fine sediment and exposing numerous small stones, upon which the light blue eggs are laid. Right: dense array of active Fish nests. (B) Two Fish nests, spaced
15 cm from each other, imaged from the active nesting area of the Filchner Trough eastern flank. The left nest is in active use, whereas the right nest contains the remains of dead Fish only. [A] Surrounding seafloor with thin layer of phytodetritus visible. [B] Faint rim of very fine black rocky material marks the extreme extent of the active Fish nest. [C] A ring of uniform grey upper sediments cut through by the nest structure forms the upper sides of each active nest. [D] A ring of slightly coarser black rock fragments makes up the lower flanks of the active Fish nest. [E] The base of the active Fish nest is made up of numerous rock fragments from a range of lithologies, presumably carried to the area by ice rafting from a range of Antarctic source lithologies. [F] Neopagetopsis ionah eggs cover much of the rocky nest base layer. [G[ Adult Fish commonly observed centrally placed within the nest. [H[ Nest containing dead Fish in various states of decay. [I] Recently deceased Fish being fed on by a Starfish. [J] At least three additional adult Fish carcasses covered with Bacterial mat(s). [K] Numerous Ophiuroids in highest abundance within and surrounding nests containing dead Fish. [L] Small Fish, potentially a scavenger. [M] Pycnogonid of
20-cm diameter, commonly observed in the vicinity of active nests. In this image, several Neopagetopsis ionah eggs seem to be visible below the Pycnogonid. (C) Unused nest arrays on the Filchner Sill and elsewhere in the Filchner Trough. [1] Station 26_7; various sessile suspension feeders occupy the center of nests. [2] Station 30_7; small sessile fauna use small rocks within the unoccupied nest as a substrate on which to settle. [3] Station 54_1; some infilling of the center of the unused nest with sediment and hydrodynamically trapped detritus. [4] Station 72_8; softer sediments render the edges of the unused nests less distinct, though the central nest floor is abundant with larger stone fragments. Purser et al. (2022).

The deepest parts of the colony were at a depth of 535 m, the shallowest 420 m. Nests were of a fairly uniform size, about 75 cm wide and 15 cm deep, and were a minimum of 25 cm from their neighbours, even in the most densely populated parts of the colony. Of the total 16 160 nests directly imaged by camera, 12 020 (79%) were currently occupied (defined by the presence of either a Fish and eggs or just eggs). Another 15% of the nests were empty, 9% contained at least one dead Fish, and 2% contained Fish but not eggs.

The nests were bowl shaped and comprised a ring of stones, with a base of fine-grained material. The Icefish kept these areas free of any debris, as well as guarding the eggs against predators and fanning them to ensure a good supply of oxygen. The outer ring of stones may serve to prevent the eggs being blown away by this fanning action. 

In addition to the occupied area, further, more widely spaced nests could be observed in the area around the colony, all empty and all less than 100 m deeper than the deepest colony nests or less than 100 m shallower than the shallowest colony nests, though the edge of the colony is quite abrupt in both directions, suggesting that the edge of the environmentally suitable zone was also abrupt, but had moved in the past, presumably in response to climate variability.

Throughout the period of the study the seafloor temperature remained between -1.0°C and 0°C. This is typical of the modified Warm Deep Water current, which flows upward onto the Weddell Shelf, through the Filchner Trough and other similar troughs. These waters have an oxygen saturation of 65-75%, which is lower than the surrounding waters, which have an average oxygen saturation of 80%, and a temperature of -2.0°C to -1.5°C, supporting the idea that the eggs need very specific environmental conditions to survive.

Chlorophyll a levels and primary production appeared to be higher above the colony area, and areas with unoccupied nests, than the surrounding waters, with the highest concentrations of particles around the modified Warm Deep Water current-High-Salinity Shelf Water interface. The majority of these particles were below 300 μm in equivalent spherical diameter, with the density of particles increasing at night, which is probably indicative of zooplankton migrating into the photic zone to feed at night. This would suggest a potential food source, both for the nesting Icefish and for their larvae, known to migrate into overlying waters following hatching.

The benthic invertebrate community around the colony was both low density and low diversity; dominated by Brittle Stars and Star Fish, and with some conspicuously large Pycnogonids ('Sea Spiders'), which were often in excess of 15 cm in diameter, and were often seen near eggs or egg husks outside of Fish nests, potentially washed out by currents or Fish movements. This is a distinctive fauna, and suggests that the Icefish are modifying the environment sufficiently to shape the local invertebrate community.

The carcasses of the Icefish appeared to provide an important food source for invertebrates. As many as four dead Fish were seen in a single nest, which since no more than two live Fish were ever seen in association with a single nest, suggest that the dead Fish, which are close to neutrally bouyant, can accumulate within nests. Brittle Stars, Starfish, Octopus, and various Fish species opportunistically feeding were observed around dead Icefish. It is likely that the breeding season takes a high toll on Icefish, as several months of tending eggs is apparently exhausting.

The area around the colony is also known to be home to a group of Weddell Seals, Leptonychotes weddelli, some of which have been tracked by satellite for long periods of time. These Seals are known to dive deeply looking for food, and to take Jonah's Icefish, suggesting that the colony may be serving as a regular food source for them. Other Seal species, such as Elephant Seals, Mirounga leonina, have also been seen in the area.

Abandoned nests outside the colony also appeared to play a significant ecological role, being colonised by sessile organisms, such as tube dwelling Polychaetes, colonial bryozoans, and Sponges. These sites also appeared to be hydrodynamically trapping phytodetritus, which would make them an excellent site for sessile organisms.

Because these observations were based upon a single observing season, a number of important questions about the breeding behaviour of the Jonah's Icefish remain unanswered. It is unclear how often the Fish build new nests; do they reuse them each year, or construct new ones? Do the Fish remain with the eggs from when they are laid till when they hatch, or do they leave to forage? How do the predators of both the Fish and their eggs behave around the colony? How do the hatchling Fish behave when they emerge? How do the Fish behave during the mating and spawning seasons? To what extent is the colony a food source for Weddell Seals, and how do they exploit it? In order to address these problems two LED light-and-camera systems were positioned 3 m above the seafloor and left collecting data, with the plan being to return and collect them in 2023 or 2024.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.

 

Homatula guanheensis: A new species of Stone Loach from Henan Province, China

The Stone Loach genus Homatula includes a number of small, benthic Fish, which live in the drainage basins of the Yellow, Yangtze, Pearl, Lancang, Nujiang and Red rivers. They are sometimes considered to be a part of the genus Paracobitis, which is morphologically similar, but the two are generally considered separate, due to their different distributions, with Homatula known only from China, and Paracobitis found only in western Asia. Studies based on the morphology of Homatula have suggested that there is more diversity that the current number of species (19-20), but to what extent this reflects variation within species rather than the presence of undescribed species remained unclear, until scientists began to apply genetic identifications to the genus.

In a paper published in the Biodiversity Data Journal on 16 June 2021, Chuanjiang Zhou, Wenwen Ma, Xi Wang, Yongtao Tang, Xiaoling Meng, and Guoxing Nie of the Engineering Technology Research Center of Henan Province for Aquatic Animal Cultivation at Henan Normal University, describe a new species of Homatula from the Guanhe River, in the HanJiang River drainage (a tributary of the Yangtze River),  in Xixia County, Henan Province.

The new species is named Homatula guanheensis, where 'guanheensis' means 'coming from Guanhe', in reference to the Guanhe River where it was found living in cave environments. Like other Stone Loaches, the new species is an elongate, slender Fish. The known specimens range from 76.9 to 109.26 mm in length, and are cylindrical, and flattened towards the rear. The head is short and flattened, and lacks scales. The snout is short, with nostrils closer to the eye than the tip. The eyes are oval, and located towards the top of the head. The lips are thick, and cover the jaw; there are three pairs of barbels. 

 

Homatula guanheensis (holotype, HNU 010048, 99.6 mm SL). (A) Lateral view; (B) Dorsal view; (C) Ventral view; (D) Mouth characters; (E) Intestine form; (F) X–ray (lateral view). Zhou et al. (2021).

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.

Manayunkia occidentalis: A new species of Sabellid Polychaete from the Pacific Northwest of the United States, and an alternate host of two Myxosporean parasites of Salmonid Fish.

Annelids are a diverse and speciose invertebrate group, particularly in marine systems. Apart from Clitellate Annelids ('Oligochaetes' and 'Leaches'), there are relatively few known freshwater species, and several of these belong to the Sabellid genus Manayunkia. Manayunkia currently contains 11 accepted nominal species, though this may need further assessment. The most recent taxa described are the marine Manayunkia mizu, described in 1996 from Papua New Guinea, and the freshwater Manayunkia zenkewitschii, described in 1997 from Lake Baikal. Currently, there are freshwater Manayunkia described from Europe and North America, and brackish/marine species known from Australia, Europe, Papua New Guinea and Brazil. Two species of Manayunkia are recorded from North America: Manayunkia aestuarina, from brackish coastal environments (though the type locality is in the UK), and Manayunkia speciosa, which was first briefly described by Joseph Leidy in 1859, from the Schuylkill River in Pennsylvania, and in much greater detail from specimens from New Jersey in 1883. The species was later reported from the Great Lakes in 1829, the Klamath and Sacramento river basins of Oregon and California in 1966, lakes in Alsaka in 1967, and lakes in North Carolina in 1971. Manayunkia speciosa has been identified as the invertebrate alternate host of two Myxosporean parasites of Salmonid Fish: Ceratonova shasta (formerly Ceratomyxa shasta) and Parvicapsula minibicornis. Myxosporeans are common Myxozoan Cnidarian parasites with complex life cycles that require two hosts: a vertebrate (usually a Fish) in which parasite Myxospores develop, and an invertebrate (usually an Annelid) in which actinospores develop. Both Ceratonova shasta and Parvicapsula minibicornis are widespread in the Pacific Northwest but have not been recorded from the Great Lakes, or east coast of North America, despite presence of both Manayunkia speciosa and susceptible Salmon hosts in these regions.

In a paper published in the journal Zootaxa on 17 March 2020, Stephen Atkinson and Jerri Bartholomew of the Department of Microbiology at Oregon State University, and Greg Rouse of the Scripps Institution of Oceanography at the University of California, San Diego, present the results of a survey based upon the hypothesis that that these two Myxozoans actually require a heretofore unrecognized Annelid host, which is present only in western North American river basins, and which has been consistently mis-identified as Manayunkia speciosa.

Atkinson et al. sampled both infected and uninfected Annelids from the two localities where the parasites were recorded originally from their annelid hosts: the Klamath River, California, and the Willamette River, near Corvallis, Oregon. Using morphology and mitochondrial Cytochrome oxidase subunit I DNA sequencing, they compared these specimens with Manayunkia speciosa samples from New Jersey and the Great Lakes. Atkinson et al. discovered that all Klamath and Willamette Manayunkia, both infected and uninfected, were a novel species, they further sequenced Annelid samples from collections made between 2006 and 2018 and identified only the new species. They did not detect any Manayunkia speciosa from either river basin.

Annelids were collected by hand at depths of 10–50 cm from rocks and periphyton from the Klamath River, California, from below Iron Gate Dam. Additional specimens were collected from the Willamette River, Oregon. Under a dissection microscope, living Annelids were separated from substrate, then examined by light microscopy either alive or fixed in 10% neutral buffered formalin, frozen for DNA analysis, or fixed in 2% glutaraldehyde in cacodylate buffer for electron microscopy. Type and voucher specimens were deposited in the Benthic Invertebrate Collection at Scripps institution of Oceanography, La Jolla, California. To confirm identity and infection status, Atkinson et al. examined additional archived Annelid samples collected opportunistically 2006–2018 by Oregon State University as part of their long term, on-going ecological and disease studies of parasites Ceratonova shasta and Parvicapsula minibicornis. These samples were collected from localities in the Klamath and Willamette Rivers. Atkinson et al. also obtained Manayunkia speciosa from Lake Superior (St. Marys River, Ontario, Canada) and South River, New Jersey, in 2009. A marine Fabriciid, Echinofabricia goodhartzorum, was used as the outgroup, since Echinofabricia has been shown to be the sister group to Manayunkia.

Live Annelids were found in clusters of tubes, most often attached to rocks or intertwined with periphyton. Females were observed frequently with broods of larvae in their tubes. Males and females with overt parasite infections often lacked gametes. Five individuals were sequenced from the type collection locality/date, with an additional 79 from archival material from the Klamath River; 10 were sequenced from the Willamette River. The five paratype specimens were up to 1.6% divergent with each other (0–6 nucleotides differed over the total alignment of 439 nucleotides), compared with a divergence of up to 2.8% among all 84 Klamath River Annelids sequenced. The 10 Willamette River specimens were up to 0.4% divergent with each other, and pairwise distances between Willamette and Klamath River specimens were 3.1–4.1%. These west coast samples were 10.5%–12.2% divergent from the Great Lakes and East Coast Manayunkia speciosa reference sequences. The parasite Ceratonova shasta was detected in 16 Annelids from the Klamath River, whereas Parvicapsula minibicornis was detected in four annelids from the Klamath River and one from the Willamette River; these parasite abundances were typical.

The new species is named Manayunkia occidentalis, which is derived from the Latin word for 'west', to contrast with Manayunkia speciosa, which occurs in eastern and central North American drainages. The holotype (SIO-BIC A12115) is a male with eight thoracic segments and three abdominal segments. Total length (unfixed) 3.0 mm, crown 0.3 mm. Body cylindrical with tapering, dorso-ventrally flattened abdomen. Body wall translucent grey with minor brown pigmentation on peristomium and pygidium, and green pigmentation on chaetiger 6. Branchial crown about 10% of total body length. Two pairs of radioles, each with six pinnules. One ventral pinnule on radiole with 4–5 yellow-white spots in life. One pair of vascularised, unbranched ventral filamentous appendages present, extending for about two-thirds length of radiolar crown, approximately same width as pinnules. Anterior peristomial ring with membranous collar, followed by posterior peristomial ring. Collar margin smooth, higher ventrally, separated by a narrow dorsal gap that corresponds with ciliated faecal groove. Peristomial eyes, black rounded spots. Pygidial eyes absent. Superior thoracic notochaetae elongate, narrowly hooded; 5–7 per fascicle (chaetigers 1–5), 4–5 per fascicle (chaetigers 6–8). Inferior thoracic notochaetae on chaetigers 1–8 short; 3–4 per fascicle except chaetiger 2, which has 6 per fascicle. Thoracic neuropodia each with 4–7 uncini in chaetigers 2–8. Thoracic uncini with rows of evenly small teeth gradually decreasing in size away from main fang. Position of chaetae and uncini reversed in abdominal segments; number of abdominal uncini per fascicle decreasing posteriorly from 22 to 9. Abdominal uncini each with multiple rows of teeth that are uniform in size; manubrium at least five times longer than dentate region, with base about two thirds the width of the dentate region. Abdominal neuropodia are elongate, narrowly hooded, decreasing posteriorly from 4–6 to 2 per fascicle.

 

Gross morphological features of Manayunkia occidentalis resolved by light microscopy: (A) multiple individuals emerged and feeding from their tubes; (B) Individual annelid with prominent vascularized appendages (va) and showing refractile spots on one feeding palp on each side (arrowheads); (C) female in reflected light, showing white oocytes (o) in segments 4–6; (D) male in reflected light showing bright spermatogonic tissue (sp) in multiple posterior segments; (E) Male in transmitted light showing parallel vascularized appendages (va) and fanned-out feeding palps nteriorly with two dark eyespots in peristomium, and granular coelom posteriorly due to presence of developing sperm. Atkinson et al. (2020).

Paratypes are similar to the holotype. However, females have oocytes in thoracic chaetigers 4–5 and a pair of pigmented spermathecae in the base of the radiolar crown. Females differ from males in having thoracic neuropodia with uncini in chaetigers 2–5 followed by 3–6 elongate hooded chaetae in neuropodia of chaetigers 6–8. 

 

Images showing chaetal characters of Manayunkia occidentalis: (A) inferior and superior notochaete typical of thoracic segments 2–8; (B) thoracic uncini; (C) abdominal uncini; (D) dorsal view of posterior thoracic segments and abdomen of male showing typical uncini in chaetigers t7 and t8 (arrowheads) and in scanning electron micrograph shown in (F); (E) dorsal view of posterior thoracic segments and abdomen of female showing neuropodia of thoracic chaetigers 6–8 with elongate neuropodia instead of uncini, seen also in scanning electron micrograph in (G) (arrowhead). (H) anterior thoracic segment of female showing notochaetae and uncini (arrowhead), characteristic of thoracic segments 2–5 in both sexes. Atkinson et al. (2020).

Manayunkia speciosa was described originally from Philadelphia, USA with subsequent reports from the Great Lakes and several west coast river basins. This Annelid is reported to be the obligate alternate host of two Myxozoan parasites Ceratonova shasta and Parvicapsula minibicornis. Unambiguous identification of the invertebrate hosts of Myxozoans, which produce the infectious stage to Fish, is essential for risk assessment and stock management as these parasites cause disease and death within populations of salmon and trout. Atkinson et al.'s findings support the hypothesis that the Annelid host of the parasites has likely been mis-identified as Manayunkia speciosa, and is actually a novel taxon Manayunkia occidentalis.

 

Morphological features of Manayunkia occidentalis resolved by scanning electron microscopy: (A) lateral view; (B) dorsal view; (C) ventral view; (D) anterior showing membranous collar (c) of the peristomal ring (pr), margin with fecal groove (fg); mucus covers the pinnules and adheres Diatoms; (E) detail of typical thoracic uncini; (F) abdominal segments and anus, showing ciliated fecal groove extending anteriorly and wrapping around to the ventral surface at boundary between abdominal and thoracic segments; (G) lateral view of thoracic segments showing contracted uncini and prominent neuropodia; (H) higher magnification view of retracted abdominal uncini. Atkinson et al. (2020).

The 94 west coast Manayunkia occidentalis specimens that Atkinson et al. characterised had cytochrome oxidase subunit I sequences at least 11% different from the reference Manayunkia speciosa sequences from Lake Superior and New Jersey. This east-west genetic divergence underpinned the rationale for describing the west coast Annelids as a distinct, novel taxon. Among the Manayunkia occidentalis specimens, the greatest genetic difference (4.1%) was between isolates from the two rivers, which are more than 500 km apart. These genetic differences are not surprising given the relative immobility of the Annelids, particularly from above- and below-dam localities, and between river basins separated by saltwater. Atkinson et al. hypothesise that similar degrees of genetic differences, with corresponding novel haplotypes, will be observed among populations in other unconnected river basins on the West Coast (Fraser, Rogue, Sacramento), and probably within large basins like the Columbia.

Atkinson et al. did not detect any Manayunkia speciosa among the 94 Annelids sampled from multiple localities in two river basins. This was surprising given historical records of that taxon in West Coast basins, particularly associated with Myxozoan parasites. The collection localities in the Klamath River included one where 'Manayunkia speciosa' was collected and sequenced previously. This published sequence is only minimally divergent (0–1%) from Manayunkia speciosa reference sequences collected from Lake Superior and the East Coast. Atkinson et al. cannot explain how these trans-continental Manayunkia speciosa sequences could be so similar, given that they observed genetic distances up to 2.8% among Manayunkia occidentalis samples from the Klamath Basin, and up to 4.1% between specimens from different West Coast river basins. Based on their survey data, Atkinson et al. postulate that Manayunkia speciosa may not be present in the Klamath or Willamette rivers, and they suspect that the earlier assignations of Klamath River Annelids as Manayunkia speciosa are incorrect. Almost all previous identifications relied on morphology, and Atkinson et al. have now shown that there are few morphological characters to distinguish the two taxa, though the markedly smaller number of pinnules in Manayunkia occidentalis is an obvious difference from Manayunkia speciosa. This and the cytochrome oxidase subunit I sequence divergence of at least 10.5% makes future discrimination between Manayunkia speciosa and Manayunkia occidentalis relatively straightforward.

Twenty-one of the 94 examined annelids were infected with either or both Ceratonova shasta and Parvicapsula minibicornis, and all were identified by sequence as Manayunkia occidentalis, and thus Atkinson et al. could not confirm that Manayunkia speciosa is a host for these Myxozoans. If Manayunkia speciosa is not a permissive host, then this would explain why Ceratonova shasta and Parvicapsula minibicornis have not become established in the Great Lakes or in East Coast river systems where Manayunkia speciosa, only, is present. It is likely, however, that Manayunkia speciosa hosts other Myxozoan species, as evidenced by detection of Ceratonova-like DNA in Annelids from the Great Lakes. Atkinson et al. predict that they will find Manayunkia occidentalis in all river basins where the parasite is found on the west coast, and none in the Great Lakes. Accordingly, they are sampling and sequencing additional Annelid populations from river basins where Ceratonova shasta and Parvicapsula minibicornis occur, to determine the phylogeography of the host, any correlation between infection and host haplotype, and if any Manayunkia speciosa sensu stricto exists on the west coast of North America.

See also...

Follow Sciency Thoughts on Facebook.