BRACHYURA Latreille, 1802

Cumberlidge, Neil & Clark, Paul F., 2018, Albertine Rift Valley endemics: three new species of freshwater crabs (Brachyura: Potamoidea: Potamonautidae) from Uganda, the Democratic Republic of the Congo, and Rwanda, Journal of Natural History 52 (25 - 26), pp. 1637-1656 : 1639-1649

publication ID

https://doi.org/ 10.1080/00222933.2018.1480812

publication LSID

lsid:zoobank.org:pub:FC681BD6-6FB2-4A14-B068-89FC3EB26605

persistent identifier

https://treatment.plazi.org/id/4F58C651-FF98-634C-FE5A-2BCCB630FCCD

treatment provided by

Felipe

scientific name

BRACHYURA Latreille, 1802
status

 

Infraorder BRACHYURA Latreille, 1802

Superfamily POTAMOIDEA Ortmann, 1896 Family POTAMONAUTIDAE Bott, 1970 Subfamily Potamonautinae Bott, 1970

Genus Potamonautes MacLeay, 1838

Potamonautes bwindi sp. nov.

( Figures 1a,b View Figure 1 ; 4a View Figure 4 ; 5a,d View Figure 5 ; 6a,d; 7a View Figure 7 ; 8a View Figure 8 )

Material examined

Type material. Uganda. Holotype (here designated): adult ♂, CW 20.2 , CL 13.7 , CH 6.8 , FW 6.8 mm, from upper reaches of Mbwa River in the Bwindi Impenetrable National Park , Kayonza area , Gombolola , Kigezi, Western Uganda, − 0.98333°S, 29.68333°E, in dense forest, clean river water, 14.4°C, 1615 m asl, coll GoogleMaps . A GoogleMaps .W.R . McCrae, 21 September 1962 ( NHMUK reg. 2018. 1) . Paratypes: three adult ♀♀, CW 22.6 , CL 15 ; CW 21 , CL 14.6 ; CW 20.6 , CL 16 mm, two subadult ♂♂, CW 18.7 , CL 13.3 ; CW 17.9 , CL 12 mm, all same data as holotype ( NHMUK reg. 2018. 2 – 4) .

Diagnosis

Based on holotype (adult ♂ CW 20.2). Carapace: postfrontal crest faint but complete, lateral ends meeting anterolateral margins; epigastric crests rounded distinctly raised; exorbital, epibranchial teeth reduced to granules; anterolateral margin posterior to epibranchial tooth smooth ( Figures 1a View Figure 1 , 4a View Figure 4 ). Third maxilliped: ischium smooth, lacking sulcus ( Figures 1b View Figure 1 , 4a View Figure 4 ); s3/ s4 incomplete, comprising two long deep grooves on lateral margins, otherwise smooth; margins of s4 low, not raised ( Figure 1b View Figure 1 ). Cheliped: dactylus (moveable finger) slim, highly arched, enclosing oval interspace, one medium tooth in mid-section, other teeth small; propodus (fixed finger) with large molar proximally ( Figure 5a View Figure 5 ); carpus distal tooth large, pointed, proximal tooth small, low ( Figure 5d View Figure 5 ); merus lined by series of small teeth, distal meral tooth large, pointed. G1 terminal article: first third straight in line with longitudinal axis of subterminal segment, median part directed outward at 45°, widened by raised rounded ventral lobe ( Figure 6d), tip curving sharply upwards ( Figure 6a,d).

Description

Based on holotype (adult ♂ CW 20.2 ) . Carapace : medium height ( CH / FW 1.0), front broad, measuring one-third CW ( FW / CW 0.33); semi-circular, urogastric, cardiac, posterior, cervical carapace grooves all distinct; postfrontal crest complete, faint, lateral ends meeting epibranchial teeth; epigastric crests faint, median sulcus between crests short, forked posteriorly; exorbital, epibranchial teeth each reduced to granule; anterolateral margin between exorbital, epibranchial teeth smooth, curving slightly outward, lacking intermediate tooth; anterolateral margin posterior to epibranchial tooth smooth ( Figure 1a View Figure 1 ); vertical sulcus on carapace branchiostegal wall faint, meeting longitudinal sulcus, dividing carapace wall into three parts; suborbital margin granulated ( Figure 1b View Figure 1 ) . Third maxilliped: exopod with long flagellum, ischium smooth lacking vertical groove ( Figure 4a View Figure 4 ). Epistomial tooth large, triangular, margins lined by large round granules ( Figure 4a View Figure 4 ). Mandible: palp two-segmented; terminal segment simple. Sternum: s2/s3 deep, completely crossing sternum; s3/s4 incomplete, comprising two long deep grooves on lateral margins, otherwise smooth; margins of s4 low, not raised ( Figure 1b View Figure 1 ). Cheliped: adult male dactylus (moveable finger) slim, highly arched, enclosing oval interspace, one medium tooth in mid-section, other teeth small; propodus (fixed finger) with large molar proximally ( Figure 5a View Figure 5 ); carpus distal tooth large, pointed, proximal tooth small, low ( Figure 5d View Figure 5 ); merus lined by series of small granules, distal meral tooth large, pointed; superior surface granulated. Pleon: outline broadly triangular with straight margins. G1: terminal article directed outward, proximal third straight in line with longitudinal axis of subterminal segment, median part directed outward at 45°, widened by raised rounded ventral lobe, tip curving sharply upwards ( Figure 6a,d). G2: terminal article long, flagellumlike ( Figure 7a View Figure 7 ). Small species, adult at CW 20 mm .

Distribution

Uganda. This species is known only from a single locality in the upper reaches of the Mbwa River in the Bwindi Impenetrable National Park , Kayonza area , Gombolola , Virunga Massif, Western Uganda (− 0.98333°S, 29.68333°E; Figure 8a View Figure 8 ) GoogleMaps .

Type locality

Upper reaches of Mbwa River in the Bwindi Impenetrable National Park , Kayonza area , Gombolola , Kigezi, Western Uganda (− 0.98333°S, 29.68333°E), in dense forest, clean river water, 14.4°C, 1615 m asl GoogleMaps .

Conservation status

An IUCN conservation assessment of P. bwindi sp. nov. has not yet been carried out, but given the fact that this species is known from only six specimens that are all from a single locality in a protected area (Bwindi Impenetrable National Park), and that no threats are known, it would probably be regarded as Data Deficient.

Ecology

This species was collected from a high-altitude locality (1615 m asl) in dense transitional/ intermediate montane forest from the clean, cool waters (14.4°C) of the upper reaches of Mbwa River in the Bwindi Impenetrable National Park. This national park is part of the Lake Victoria Basin Freshwater Ecoregion 521 ( Thieme et al. 2005; Abell et al. 2008). The

Mbwa River is a tributary of the Ishasha River that flows north into Lake Rutanzige which is part of the Nile River basin. This remote national park is mostly accessible only on foot and is part of the Bwindi Impenetrable Forest that borders the Virunga National Park in the DRC. This is the first record of an endemic species of freshwater crab from the Bwindi Impenetrable National Park.

Etymology

The new species is named for the Bwindi Impenetrable National Park which lies in southwestern Uganda where this species was first collected. The specific epithet bwindi is used as a Latin noun in apposition. The vernacular name is the Bwindi crab.

Remarks

Potamonautes bwindi sp. nov. differs from P. kivu sp. nov. and P. rwenzori sp. nov. in that the distal tooth on the merus of the cheliped is large and pointed followed by a row of small teeth ( Figure 1a,b View Figure 1 ) [vs either a small and pointed distal meral tooth ( P. kivu sp. nov.), or a blunt and low distal meral tooth ( P. rwenzori sp. nov.), followed by a row of granules in P. kivu sp. nov. and P. rwenzori sp. nov.; Figures 2b View Figure 2 and 3b View Figure 3 ]; and the cheliped dactylus of the adult male is highly arched and encloses a broad oval interspace when closed ( Figure 5a View Figure 5 ) (vs a cheliped dactylus of the adult male that is slightly curved, not arched, and encloses a long narrow interspace in P. kivu sp. nov. and P. rwenzori sp. nov.; Figure 5b,c View Figure 5 ).

Potamonautes bwindi sp. nov. differs from other, similar small-bodied species of freshwater crabs found in Uganda in that s3/s4 ( Figure 2a View Figure 2 ) comprises two long deep grooves at the margins and is otherwise faint or absent (vs two short shallow grooves at the margins in P. elgonensis Cumberlidge and Clark, 2010a and P. kanstyore Cumberlidge and Clark, 2017 ); the third maxilliped ischium is smooth and lacks a vertical sulcus ( Figure 2a View Figure 2 ) (vs a third maxilliped ischium with a deep vertical sulcus in P. loveni ( Colosi, 1924) , P. mutandensis , P. rukwanzi Corace, Cumberlidge and Garms, 2001 , and P. williamsi Cumberlidge and Clark, 2010a ); the cheliped merus has a large pointed distal meral tooth ( Figure 1a View Figure 1 ) (vs a small, low distal meral tooth in P. elgonensis , P. imatongensis Cumberlidge and Clark, 2016 ; P. loveni , P. morotoensis Cumberlidge and Clark, 2016 ; P. rukwanzi and P. williamsi ); the distal tooth on the cheliped carpus is small, broad and low ( Figure 5d View Figure 5 ) (vs a large, pointed distal tooth in the cheliped carpus in P. busungwe Cumberlidge and Clark, 2017 , P. entebbe Cumberlidge and Clark, 2017 ; P. imatongensis and P. kantsyore Cumberlidge and Clark, 2017 ); and the tip of the G1 terminal article curves sharply upwards ( Figure 6a,d) (vs a G1 terminal article with either a straight or a slightly upturned tip in P. busungwe , or a straight tip in P. amalerensis ( Rathbun, 1935) , P. busungwe , P. elgonensis , P. entebbe , P. imatongensis , P. loveni , P. morotoensis and P. mutandensis (cf. Cumberlidge and Clark 2010a, 2010b, 2016, 2017; Cumberlidge and Meyer 2011).

NHMUK

Natural History Museum, London

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Loc

BRACHYURA Latreille, 1802

Cumberlidge, Neil & Clark, Paul F. 2018
2018
Loc

Potamonautes bwindi

Cumberlidge & Clark 2018
2018
Loc

POTAMONAUTIDAE

Bott 1970
1970
Loc

Potamonautinae

Bott 1970
1970
Loc

POTAMOIDEA

Ortmann 1896
1896
Loc

Potamonautes

MacLeay 1838
1838