Potamonautes amathole: A new species of Freshwater Crab from the montane forests of Eastern Cape Province, South Africa.

The Potamonautidae are a group of Freshwater Crabs found across Africa and its associated islands. In South Africa, this group is represented by 26 species divided into two genera, Potamonautes and Maritimonautes, although this is likely to be an underestimate, as the group is known to contain numerous cryptic species, which resemble one-another closely, but are reproductively isolated and can generally only be identified by genetic analysis. A number of these Crabs have recently been described from forests in South Africa, an environment which covers only 0.4% of the country's land area, but which is it's most biodiverse by area. The two largest remaining patches of forests in South Africa are Knysna and Amathole, the latter of which is found in the Amathole Mountain Range, part of the Great Escarpment of South Africa.

In a paper published in the journal ZooKeys on 4 May 2023, Nasreen Peer of the Department of Botany and Zoology at Stellenbosch University, Gavin Gouws of the South African Institute for Aquatic Biodiversity, Lazola Maliwa of the Albany Museum, Nigel Barker and Paul Juby of the Department of Plant and Soil Sciences at the University of Pretoria, and Renzo Perissinotto of the Institute for Coastal & Marine Research at Nelson Mandela University, describe a new species of Potamonautid Crab from the Hogsback and Katberg forests in the Amathole Mountains of Eastern Cape Province.

The new species is placed in the genus Potamonautes, and given the specific name amathole, in reference to the Amathole Mountains, to which the species appears to be endemic; in isiXhosa the term  'amathole' means 'calves', and is used to refer to the mountain range, the forest, and municipal district. The species is distinguished by a smooth carapace and a highly arched major claw.

Potamonautes amathole male holotype (MB-A094813) in (a) dorsal view and (b) ventral view. Peer et al. (2023).

Genetically, Potamonautes amathole was found to be closely related to the small-bodied montane Freshwater Crabs of the Cape Fold Mountains in Western Cape Province (which are also associated with the Great Escarpment); it represents the first member of this group from the Eastern Cape.

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Temnocephala ivandarioi: A new species of endosymbiotic Flatworm from a Colombian Freshwater Crab.

The Rhabdocoela is an order of Platyhelminth Flatworms with about 1700 species known across the globe. The majority of these are freeliving, often being predators specialising in the hunting of Cladocerans (Water Fleas), while others feed on Algae and sometimes incorporate them into their tissues to form symbiotic relationships. One group of Rhabdocoels, the Temnocephalidae, are not freeliving, but rather ectosymbionts (organisms that live on the surface or within the body cavities of other organisms but do not obtain food from them) or parasites of other animals. The genus Temnocephala includes 37 species of symbiotic freshwater Rhabdocoels from the Neotropics, which are associated with a large variety of hosts including Chelonians (3), Mollusks (6), Insects (7) and Crustaceans (21). At present, only two species have been described from Colombia, Temnocephala colombiensis, an ectosymbiont of the Gastropod Pomacea sp., and Temnocephala icononcensis, hosted by the Pseudothelphusid Crabs Hypolobocera bouvieri, Phallangothelphusa dispar, and Strengeriana cajaensis.

In a paper published in the journal ZooKeys on 12 March 2020, Carolina Lenis, Freddy Ruiz, and Carlos Muskus of the Programa de Estudio y Control de Enfermedades Tropicales at the Universidad de Antioquia, and Antonio Marcilla and Imelda Vélez of the Departamento de Farmacia y Tecnología Farmacéutica y Parasitología, at the Universitat de València, describe a new species of Rhabdocoels from the branchial chambers of the Freshwater Crab Valdivia serrata in Amazonas Department, Colombia.

Eleven specimens of Valdivia serrata were manually collected from the Reserva Natural Tanimboca. The specimens were transported alive to the Programa de Estudio y Control de Enfermedades Tropicales laboratory and identified using a Decapod key. Specimens of Temnocephala were removed
from the branchial chambers of host crabs under a stereomicroscope, rinsed in saline solution, and preserved in cold alcohol-formalin-acetic acid and 70% ethanol for morphological identification by light microscopy; or fixed in 2.5% glutaraldehyde for observation by Scanning Electron Microscopy. The Temnocephalans were identified by focusing on the morphology of the reproductive complex, the shape of the epidermal excretory syncytial plates and the deposit areas of the eggs in the host.

The new species is named Temnocephala ivandarioi, in honour of Iván Darío Vélez Bernal for his outstanding contributions to the study of helminthology and the understanding of tropical diseases in Colombia. The species has a body 1.36–2.26 mm in length (excluding the tentacles), and 1.18–1.56 mm wide, with an adhesive disk on the ventral surface and eyespots with red pigmentation.

Temnocephala ivandarioi and Valdivia serrata (A) specimen of Temnocephala ivandarioi showing an egg, ventral view, (B) adult specimen stained in Meyer´s paracarmine, (C) specimen stained
in Borax carmine (D) male specimen of Valdivia serrata, (E) abdomen, (F) gonopods, lateral view. Scale bars are 200 μm in (A)–(C), 10 mm in (D)–(F). Lenis et al. (2020).

In Colombia more than 132 species of Decapod Crustaceans have been recorded, while only two associated species of Temnocephalans have been reported to date: Temnocephala icononcensis and Temnocephala ivandarioi. The great diversity of these potential hosts suggests that most temnocephalans remain undescribed.

Temnocephala ivandarioi details of epidermal excretory syncytial plates and eggs. (A) antero-lateral area observed with Scanning Electron Microscope showing leftmost tentacle and left epidermal excretory syncytial plate, arrow showing contour and position of excretory pores (n). (B) Line drawing of entire specimen showing the epidermal excretory syncytial plates. (C) egg observed with Scanning Electron Microscope showing the filament (fi), peduncle (pe), and plane of fracture of the operculum (pf ). (D) Line drawing of a whole egg showing the oblique fracture plane to the longitudinal axis of the egg. (E) Live adult specimen showing red eyespot pigment. (F) Unhatched egg showing the filament (fi). (G), (H) Live eggs deposited on branchial chambers of Valdivia serrata. Scale bars are 100 μm in (A)–(F), and 1mm in (G) and (H). Lenis et al. (2020).

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Louisea nkongsamba & Louisea yabassi: Two new species of freshwater Crabs from Cameroon.

Crabs are Decapod Crustaceans related to Shrimps, Crayfish and Lobsters. Most Crabs occupy marine environments; however Freshwater and Land Crabs are widespread in the tropics. Members of the Family Potamonautidae are found across Africa, as well as Madagascar, the Seychelles, Zanzibar, Mafia, and Pemba islands in the Indian Ocean, and Bioko, São Tomé, Príncipe, and Sherbro islands in the Atlantic. The genus Louisea is known only from Cameroon, with two described species, Louisea edeaensis from the Lake Ossa wetland complex, and Louisea balssi from Kumba and Mt. Manengouba.

In a paper published in the journal ZooKeys on 17 Ocrober 2019, Pierre Mvogo Ndongo of the Department of Management of Aquatic Ecosystems at the University of Douala at Yabassi, the Museum für Naturkunde at the Leibniz-Institut für Evolutions und Biodiversitätsforschung, and the the Department of Biology at Northern Michigan University, Thomas von Rintelen, also of the Museum für Naturkunde at the Leibniz-Institut für Evolutions und Biodiversitätsforschung, and Neil Cumberlidge, also of the Department of Biology at Northern Michigan University, describe two new species of Louisea, both from Cameroon.

The first new species is named Louisea yabassi, in reference to the Yabassi Coastal Rain Forest where it was discovered. The species is described from two specimens, an adult male 18.11 mm wide and 12.78 mm long, and a subadult male 13.82 mm wide and 10.61 mm long. Both were collected in 1909 by Fritz Wilhelm Riggenbach, and were found in the collection of the Museum für Naturkunde. Louisea yabassi has a smooth, flat and nearly oval carapace, and unequal claws, with the right being larger than the left.

Largest adult male of Louisea yabassi. from Yabassi  (missing left p2–p5, and right cheliped and p2, p3). Scale bar is 8.42 mm. Mvogo Ndongo et al. (2019).

The second new species is named Louisea nkongsamba, in reference to Nkongsamba, the closest town to the Nlonako Wildlife Reserve, where the species was discovered. This species is described from two adult male specimens collected by Pierre Mvogo Ndongo, the larger of these being 20 mm wide and 14.85 mm long, the smaller 18.38 mm wide and 13.32 mm wide. Louisea nkongsamba has a smooth oval carapace, a stout but different-sized claws and slender walking legs. It is dark green or brown in life.

Second largest adult male of Louisea nkongsamba from Mt. Nlonako. Scale bar is 11.63 mm. Mvogo Ndongo et al. (2019).

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Salangathelphusa peractio: A new species of Freshwater Crab from Langkawi Island, Malaysia.

Crabs are Decapod Crustaceans related to Shrimps, Crayfish and Lobsters. Most Crabs occupy marine environments; however Freshwater and Land Crabs are widespread in the tropics, particularly in Southeast Asia, where they are particularly diverse and where several new species are discovered every year. Members of the family Gecarcinucidae are obligate Freshwater Crabs found found from India and Sri Lanka east across Southeast Asia and Indonesia as far as Australia.

In a paper published in the journal ZooKeys on 23 October 2017, Peter Ng of the Lee KongChian Natural History Museum at the National University of Singapore, describes a new species of Gecarcinucid Freshwater Crab from Langkawi Island. off the northwest coast of Peninsula Malaysia.

The new species is placed in the genus Salangathelphusa, and given the specific name peractio, meaning 'end of the story', in reference to the fact that Peter Ng has carried out fieldwork on Langkawi Island for 30 years, was somewhat surprised to find a new species on such a small and heavily surveyed island, and does not expect to describe any more species from the island. These are small, squarish, orange-brown Crabs. The males are larger than the females, reaching slightly over 25 mm, compared to about 15 mm. The species was found in fast-flowing, rocky, streams at the southern base of Gunung Raya, the highest peak on the island (881 m). 

 Salangathelphusa peractio, male (22.4 × 17.7 mm). Ng (2017).

All of the observed Crabs were living within an area of a few hundred square metres, within Lubuk Semilang Park, though this area is covered with dense vegetation, and similar environments nearby are very hard to access. The Lubuk Semilang Park is dedicated to recreation, rather than conservation, and is open to a range of activities which might be harmful to the Crabs, as such Ng considers the species should be considered vulnerable until further information is available.

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Kani maranjandu: A new species of tree-dwelling Crab from the Western Ghats of Kerala, India.

The Western Ghats of southwestern India are considered to be a biodiversity hotspot, with a high number of endemic (not found anywhere else) species of animals and plants. A wide range of groups of organisms have been studied in this area, including freshwater Crabs, many species of which have been described from the Western Ghats in recent years, though to date no Crabs from other environments have been described from this region.

In a paper published in the Journal of Crustacean Biology on 3 April 2017, Appukuttannair Biju Kumar and Smrithy Raj of the Department of Aquatic Biology and Fisheries at the University of Kerala and Peter Ng of the Lee Kong Chian Natural History Museum at the National University of Singapore, describe a tree-dwelling Crab from the Kottoor Reserve Forest in the Western Ghats of Kerala State in southwest India.

The new species is named Kani maranjandu, where ‘Kani’ honours the Kanikkaran or Kani people of Kerala, who live in the area where the Crabs were found and helped in the collection of specimens, and ‘maranjandu’ means ‘Tree-Crab’ in Malayalam. The Crabs are oval in shape with long legs, bluish-black in colour with an orange underside. The largest male found measured 42.6 x 30.8 mm while the largest female was 40.6 x 30.44 mm. 

Kani maranjandu, specimen on tree trunk. Sali Palode in Kumar et al. (2017).

The Crabs were found living only in trees with flooded bowls, they were found in a variety of trees, including Bedda Nut Tree, Terminalia bellirica, Flowering Murdah, Terminalia paniculata, Malabar Ironwood, Hopea parviflora, True Cinnamon Tree, Cinnamomum verum, and Evergreen Tropical Blackboard Tree, Alstonia scholaris. They were found in trees with bowls at a range of heights, from close to the ground to about 10 m up, and were observed consuming leaves, seeds and invertebrates. They were found in degraded forests close to settlements within the Kottoor Reserve Forest, part of the Agasthyamala Biological Park.

 

(A) Degraded forest area near the tribal settlement at Agathyamala Biological Park, Kottoor Reserve Forest, Kottoor, Kerala, India, where specimens of Kani maranjandu were found; (B) tree fork of Terminalia paniculata; (C) phytotelm in tree fork of Terminalia paniculata; (D) male specimen (33.1 × 24.3 mm) of Kani maranjandu collected from inside a phytotelm in a tree fork of Terminalia paniculata; (E) tree hollow of Cinnamomum verum, where individuals of the new species may live; (F), (G) when approached by members of the Kani tribe, the Crabs climb up the trunk of Cinnamomum verum, the tribesmen then cut a series of holes in trees to climb up after them. Kumar et al. (2017).

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