Potamonautes kantsyore, Cumberlidge & Clark, 2017

Cumberlidge, Neil & Clark, Paul F., 2017, Description of three new species of Potamonautes MacLeay, 1838 from the Lake Victoria region in southern Uganda, East Africa (Brachyura: Potamoidea: Potamonautidae), European Journal of Taxonomy 371, pp. 1-19 : 10-13

publication ID

https://doi.org/10.5852/ejt.2017.371

publication LSID

lsid:zoobank.org:pub:661B464B-D514-4110-8531-295432A69767

DOI

https://doi.org/10.5281/zenodo.3852170

persistent identifier

https://treatment.plazi.org/id/8EB2261D-E474-4809-B415-382269BF354E

taxon LSID

lsid:zoobank.org:act:8EB2261D-E474-4809-B415-382269BF354E

treatment provided by

Carolina

scientific name

Potamonautes kantsyore
status

sp. nov.

Potamonautes kantsyore sp. nov.

urn:lsid:zoobank.org:act:8EB2261D-E474-4809-B415-382269BF354E Figs 3 View Fig A–B, 4C, 5E–F, 6C, F, 7; Tables 1 View Table 1 , 3 View Table 3 Diagnosis

Carapace of medium height ( CH /FW 1.2; Fig. 3B View Fig ); exorbital tooth low, blunt, epibranchial tooth reduced to granule, postfrontal crest complete, faint medially, lateral ends well defined, meeting epibranchial teeth; anterolateral margin posterior to epibranchial tooth finely serrate, almost smooth ( Fig. 3A View Fig ); carapace sidewall vertical sulcus meeting anterolateral margin ( Fig. 3B View Fig ). Third maxilliped ischium with vertical sulcus ( Fig. 3B View Fig ); s3/s4 not visible except for two short deep notches at edges ( Fig. 3B View Fig ). Inferior margins of merus of cheliped with series of small granules, distal tooth pointed; cheliped carpus distal tooth large, pointed, proximal tooth small, one-third as large as distal tooth ( Fig. 3B View Fig ). Fixed finger (propodus) of major cheliped of adult male with large teeth along cutting edges, largest molars proximal, movable finger (dactylus) cutting edge with only small even granules, dactylus not arched, encompassing long narrow interspace when closed ( Fig. 5F View Fig ). G1 terminal article straight, directed outward at 45° angle to longitudinal axis of subterminal segment, curving outward throughout, tip slightly upturned ( Fig. 6C, F View Fig ).

Etymology

The new species is named for Kantsyore Island, which is located in the Kagera River (where it is about 130 m wide) at a locality that is about 120 km west of the point where the river enters Lake Victoria. The name is used as a noun in apposition. Vernacular name: the Kantsyore Island crab.

Material examined

Holotype (here designated)

UGANDA: adult ♂, CW 16.8, CL 11.6, CH 5.5, FW 4.6 mm, Ankole , Mbarara District , Kantsyore (Toni Nuti’s) Island, in the Kagara River, 12.9 km E of Kikagati, - 1.04216°S, 30.67056°E, 1280 m a.s.l., 19–20 Aug. 1967, J.S. Williams leg. ( NHMUK 2017.29 View Materials ).

GoogleMaps

Paratypes

UGANDA: 1 adult ♂, CW 15.6, CL 11.6, CH 5.5, FW 4.6 mm, same collection data as for holotype ( NHMUK 2017.30); 4 adult ♀♀ (CWs 16.1, 15.7, 15.5, 15.3), 1 subadult ♀ ( CW 14.2), 1 subadult ♂ (CW 13.2 mm), same collection data as for holotype ( NHMUK 2017.31–36).

Description

Carapace of medium height ( CH /FW 1.2; Fig. 3B View Fig ); front broad, measuring one-third CW (FW/CW 0.3; Fig. 3A View Fig ). Semi-circular, urogastric, cardiac, posterior and cervical carapace grooves all faint. Postfrontal crest complete, faint, lateral ends well defined, meeting epibranchial teeth; exorbital tooth low, blunt. Epigastric crests faint, median sulcus between crests short, forked posteriorly. Epibranchial tooth reduced to granule; anterolateral margin between exorbital, epibranchial teeth smooth, curving slightly outward, lacking intermediate tooth; anterolateral margin posterior to epibranchial tooth finely serrate, almost smooth ( Fig. 3A View Fig ); carapace sidewall vertical sulcus faint, incomplete, beginning at longitudinal sulcus, not meeting anterolateral margin, dividing sidewall into three parts ( Fig. 4C View Fig ). Suborbital margin granulated ( Fig. 4C View Fig ). Third maxilliped exopod with long flagellum, ischium with faint vertical sulcus ( Fig. 4C View Fig ). Epistomial tooth large, triangular, edges lined by large, round granules ( Fig. 4C View Fig ). Mandibular palp 2-segmented; terminal segment simple, s2/s3 deep, completely crossing sternum; s3/s4 not visible except for 2 short, deep notches at edges; margins of s4 flat, not raised; s4/e4, s5/e5, s6/e6 and s7/e7 all faint. Inferior margins of merus of cheliped with series of small granules, distal tooth pointed; two teeth on inner margin of cheliped carpus, both small, pointed; superior surface of merus granulated ( Fig. 3B View Fig ). Fixed finger (propodus) of major cheliped of adult male with large teeth along cutting edges, largest molars proximal, movable finger (dactylus) cutting edge with only small, even granules, dactylus not arched, encompassing long narrow interspace when closed ( Fig. 5 View Fig E–F). Pleon outline broadly triangular, with straight edges ( Fig. 3B View Fig ). G1 terminal article straight, directed outward at 45° angle to longitudinal axis of subterminal segment, with slightly upturned tip ( Fig. 6C, F View Fig ). G2 terminal article long (0.5 × length of G2), flagellum-like.

SIZE. Small species, adult size range between CW 15.3 and 16.8 mm.

COLOUR. Preserved specimens uniformly light brown.

Distribution

This species is known from only a single locality on Kantsyore Island in the Kagara River, 12.9 km east of Kikagati, where the river forms the border between Uganda and Tanzania ( Fig. 7 View Fig ).

Ecology

This river-living species was captured on Kantsyore Island in the Kagera River (water temperature 20–24°C) from between tree roots using meat as bait. The new species was collected in the same stretch of river as P. niloticus , a large-bodied, widely distributed species found throughout the Nile River basin ( Cumberlidge 2009; Cumberlidge & Clark 2010 b).

Conservation status

An IUCN extinction risk assessment of Potamonautes kantsyore sp. nov. has not yet been carried out, but given the fact that this species is known for only a few specimens from a single locality, it would probably be regarded as Data Deficient.

Remarks

Potamonautes kantsyore sp. nov. is superficially similar to several other species in this genus that share the following characters: reduced or absent exorbital and epibranchial teeth; a smooth anterolateral margin immediately behind the epibranchial tooth; and a thoracic sternum with a s3/s4 which is incomplete and deep at the sides but faint or absent in the middle. Ugandan crabs that share this suite of characters include P. rukwanzi , P. williamsi , P. mutandensis , P. morotoensis and P. imatongensis . Potamonautes emini (Hilgendorf, 1892) , from a geographically close locality in northwestern Tanzania, was also compared.

Potamonautes kantsyore sp. nov. can be distinguished from P. rukwanzi by the distal tooth on the cheliped merus, which is large, sharp and pointed in P. kantsyore sp. nov. ( Fig. 3B View Fig ) (vs small, blunt and low in P. rukwanzi ). Potamonautes kantsyore sp. nov. differs from P. willliamsi , P. mutandensis , P. morotoensis and P. imatongensis in that the proximal tooth on the inner margin of the cheliped carpus of P. kantsyore sp. nov. is pointed and almost as large as the distal tooth ( Fig. 3A View Fig ) (vs a weak, low and blunt proximal tooth in the other species) and the ischium of the third maxilliped is smooth in P.kantsyore sp. nov. ( Fig. 3B View Fig ) (vs with a distinct vertical sulcus in the other species). Potamonautes kantsyore sp. nov. is superficially similar to P. emini from northwest Tanzania ( Reed & Cumberlidge 2006) in that both are small species and both have smooth carapace margins. The most important differences between these two species are that the postfrontal crest is weak in P. kantsyore sp. nov. (vs distinct in P. emini ) and the ischium of the third maxilliped has a faint vertical sulcus in P. kantsyore sp. nov. (vs smooth in P. emini ) ( Bott 1955: pl. XIV, figs 1a–d; Reed & Cumberlidge 2006; Meyer & Cumberlidge 2011). Potamonautes kantsyore sp. nov. can be distinguished from P. entebbe sp. nov. by examination of s3/s4, which is almost completely absent except for two short notches on the external margins of the sternite ( Fig. 3B View Fig ) (vs deep at the edges and faint in the middle in P. entebbe sp. nov., Fig. 1B View Fig ). Finally, P. kantsyore sp. nov. can be distinguished from P. busungwe sp. nov. by examination of the ischium of the third maxilliped, which has a faint vertical sulcus ( Fig. 3B View Fig ) (vs smooth in P. busungwe sp. nov.; Fig. 2B View Fig ).

NHMUK

Natural History Museum, London