Potamonautes entebbe, 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 : 4-7

Potamonautes entebbe sp. nov.

urn:lsid:zoobank.org:act:566C13F5-AE87-4E75-8118-704C6F081488 Figs 1 A–B, 4A, 5A–B, 6A, D, 7; Table 1 Diagnosis

Postfrontal crest faint but complete, lateral ends meeting anterolateral margins at epibranchial teeth; exorbital, epibranchial teeth each reduced to granule; anterolateral margin posterior to epibranchial tooth smooth ( Figs 1A , 4A ). Third maxilliped ischium lacking vertical sulcus ( Figs 1B , 4A ); s3/s4 V-shaped, deep at sides, faint in middle; margins of s4 distinctly raised, thickened ( Fig. 1B ). Propodus, dactylus of major cheliped of adult male slim, elongated, both lined by small teeth, dactylus highly arched, enclosing oval interspace when closed ( Figs 1 A–B). Cheliped carpus inner margin distal tooth large, pointed, proximal tooth small, broad, pointed ( Figs 1B , 5 A–B). G1 terminal article short (0.25 × length of G1), slim, straight, curving gently outward, needle-shaped, evenly tapering, tip straight ( Fig. 6A ).

Etymology

The new species is named for the city of Entebbe, Uganda, which lies on the northern shore of Lake Victoria where this species was first collected. The specific epithet is used as a noun in apposition. Vernacular name: the Entebbe crab.

Material examined

Holotype (here designated)

UGANDA: adult ♂, CW 35.0, CL 23.2, CH 11.6, FW 9.4 mm, Entebbe, N shore of Lake Victoria , 1.04216° N, 30.67056° E, 11 Aug. 1955, Captain C.R.S. Pittman leg. ( NHMUK 1955.11.8.26 ).

Paratype

UGANDA: subadult ♀, CW 8.5 mm, same collection data as for holotype ( NHMUK 1955.11.8.27).

Description

Based on holotype (adult male CW 35 mm). Carapace outline transversely oval, inflated ( CH /FW 1.24; Fig. 1A ), front broad measuring one-third CW (FW/CW 0.27; Fig. 4A ). Postfrontal crest faint but complete, lateral ends meeting epibranchial teeth; epigastric crests distinct, median sulcus between crests short, forked posteriorly; semi-circular, urogastric, cardiac, posterior and cervical carapace grooves all faint. Exorbital tooth very low, blunt, epibranchial tooth reduced to granule; anterolateral margin between exorbital, epibranchial teeth smooth, lacking intermediate tooth, anterolateral margin posterior to epibranchial tooth smooth ( Fig. 1A ). Suborbital margin granular ( Fig. 4A ). Carapace sidewall vertical sulcus faint, incomplete, meeting longitudinal sulcus, dividing sidewall into three parts. Third maxilliped exopod with long flagellum, ischium lacking vertical sulcus ( Fig. 4A ). Epistomial tooth large, triangular, edges lined by granules ( Fig. 4A ). Mandibular palp 2-segmented; terminal segment simple; s2/s3 deep, running horizontally across sternum; s3/s4 V-shaped, deep at sides, faint in middle; margins of s4 distinctly raised, thickened ( Fig. 1B ); s4/e4, s5/e5, s6/e6 and s7/e7 all visible ( Fig. 1B ). Chelipeds of adult male unequal; fixed finger (propodus) and movable finger (dactylus) of major cheliped slim, elongated, both lined by small teeth, moveable finger highly arched, encompassing oval interspace when closed ( Fig. 5 A–B). Two pointed teeth on inner margin of cheliped carpus, distal tooth of medium size, proximal tooth small ( Fig. 1A ). Inferior margins of merus of cheliped with series of small sharp teeth, distal tooth pointed; superior surface of merus with carinae ( Fig. 1 A–B). Pleon outline broadly triangular, with straight edges ( Fig. 1B ). G1 terminal article short (0.25 × length of G1), curving gently outward, broad at base, tapering evenly to straight tip ( Fig. 6 A, D ). G2 terminal article long (0.5 × length of G2), flagellum-like.

SIZE. Medium-sized species, adult at CW 35 mm.

COLOUR. Preserved specimens uniformly light brown.

Distribution

This species is known only from two specimens collected from a single locality at Entebbe, Uganda in the Lake Victoria drainage basin ( Fig. 7 ). Although only sparse details of the habitat were provided by the collector, the inference is that this species was either collected on the Lake Victoria shoreline itself, or in a stream or river close to where it joins the lake.

Ecology

Little is known about the ecology of this species. Potamonautes entebbe sp. nov. is not found in a protected area and was collected from a locality that is either in or near Lake Victoria, adjacent to the city of Entebbe. At the time the specimens were collected (1955) this area was relatively undisturbed, but it is now under increasing pressure from anthropogenic pollution and disturbance.

Conservation status

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

Remarks

Potamonautes entebbe sp. nov. is superficially similar to several other species in this genus from Uganda that all share the following characters: a medium body size at maturity (CW 30 mm and above); a complete postfrontal crest; reduced or absent exorbital and epibranchial teeth; a smooth anterolateral margin behind the epibranchial tooth; and a male major cheliped with a slim, elongated, highly arched dactylus. Ugandan crabs that share this suite of characters include four species from southeastern Uganda ( P. loveni (Colosi, 1924) , P. elgonensis Cumberlidge & Clark, 2010 , P. williamsi (Cumberlidge & Clark, 2010) and P. amalerensis (Rathbun, 1935)) , two from northern Uganda ( P. morotoensis Cumberlidge & Clark, 2016 , and P. imatongensis Cumberlidge & Clark, 2016 ), and two from western Uganda ( P. aloysiisabaudiae (Nobili, 1906) and P. rukwanzi Corace, Cumberlidge & Garms, 2001 ).

Potamonautes entebbe sp. nov. differs from P. loveni and P. williamsi in that the proximal tooth on the inner margin of the cheliped carpus of P. entebbe sp. nov. is pointed and subequal to the distal tooth ( Fig. 1A ) (vs both teeth weak, low and blunt in P. loveni and P. williamsi ). Potamonautes entebbe sp. nov. differs from P. aloysiisabaudiae , P. busungwe sp. nov., P. elgonensis and P. kantsyore sp. nov. in that the G1 terminal article of P. entebbe sp. nov. has a straight tip ( Fig. 6A, D ) (vs a G1 terminal article that has either a slightly or distinctly upcurved tip in these other species) ( Chace 1942; Bott 1955; Cumberlidge & Clark 2010a). Potamonautes entebbe sp. nov. differs from P. williamsi as follows: the distal tooth on the inner margin of the carpus of the cheliped is strong and pointed ( Fig. 1A ) (vs small and low in P. williamsi ) and s3/s4 is deep at the edges and faint medially ( Fig. 1B ) (vs not visible except for two short notches on the external margins of the sternite in P. williamsi ) ( Cumberlidge & Clark 2010a). Potamonautes entebbe sp. nov. differs from P. rukwanzi by the third maxilliped ischium, which has a faint, barely visible sulcus ( Fig. 1B ) (vs a distinct and complete sulcus in P. rukwanzi ) ( Corace et al. 2001).

Figures

Fig. 1. Potamonautes entebbe sp. nov., holotype, adult ♂, CW 35 mm, from Entebbe, southern Uganda (NHMUK 1955.11.8.26). A. Whole animal, dorsal view. B. Whole animal, ventral view. Scale bars: 6.3 mm. Photographs by Phillip Crabb, NHMUK.

Fig. 4. Frontal view of carapace. A. Potamonautes entebbe sp. nov., holotype, adult ♂, CW 35 mm, from Entebbe, Lake Victoria, southern Uganda (NHMUK 1955.11.8.26). – B. P. busungwe sp. nov., holotype, adult ♂, CW 21.5 mm, from Busungwe Island, Lake Victoria,, southern Uganda (NHMUK 2017.37). – C. P. kantsyore sp. nov., holotype, adult ♂, CW 16.8 mm, from Kantsyore Island in the Kagera River, southern Uganda (NHMUK 2017.29). Scale bars: A = 2.34 mm; B = 3.1 mm; C = 3.3 mm. Photographs A–B by Phillip Crabb, NHMUK.

Fig. 5. Frontal view of left and right chelipeds. A–B. Potamonautes entebbe sp. nov., holotype, adult ♂, CW 35 mm, from Entebbe in southern Uganda (NHMUK 1955.11.8.26). – C–D. Potamonautes busungwe sp. nov., holotype, adult ♂, CW 21.5 mm, from Entebbe in southern Uganda (NHMUK 2017.37). – E–F. Potamonautes kantsyore sp. nov., holotype, adult ♂, CW 16.8 mm, from Kantsyore Island in the Kagera River in southern Uganda (NHMUK 2017.29). Scale bar: A–B = 2.3 mm; C–D = 3.1 mm; E–F = 3.3 mm. Photographs A–D by Phillip Crabb, NHMUK.

Fig. 6. G1, ventral view (A–C) and dorsal view (D–F). A, D. Potamonautes entebbe sp. nov., holotype, adult ♂, CW 35 mm, from Entebbe, southern Uganda (NHMUK 1955.11.8.26). – B, E. P. busungwe sp. nov., holotype, adult ♂, CW 21.5 mm, from Busungwe Island, Lake Victoria (NHMUK 2017.37). – C, F. P. kantsyore sp. nov., holotype, adult ♂, CW 16.8 mm, from Kantsyore Island in the Kagera River, southern Uganda (NHMUK 2017.29). Scale bars: A, D = 2.3 mm; B, E = 3.1 mm; C, F = 3.3 mm.

Fig. 7. Distribution map showing the known localities of Potamonautes entebbe sp. nov. (black triangle), P. busungwe sp. nov. (black circle) and P. kantsyore sp. nov. (black star) in Uganda, East Africa. For exact localities, see text.