Louisea nkongsamba, Mvogo Ndongo, Pierre A., von Rintelen, Thomas & Cumberlidge, Neil, 2019

Mvogo Ndongo, Pierre A., von Rintelen, Thomas & Cumberlidge, Neil, 2019, Taxonomic revision of the endemic Cameroonian freshwater crab genus Louisea Cumberlidge, 1994 (Crustacea, Decapoda, Brachyura, Potamonautidae), with descriptions of two new species from Nkongsamba and Yabassi, ZooKeys 881, pp. 135-164 : 135

publication ID	https://dx.doi.org/10.3897/zookeys.881.36744
publication LSID	lsid:zoobank.org:pub:B058CA15-6A3D-41A1-9ADF-D00384234D8E
persistent identifier	https://treatment.plazi.org/id/141A1FD3-DF3B-4E84-9296-5AA5A26A3B68
taxon LSID	lsid:zoobank.org:act:141A1FD3-DF3B-4E84-9296-5AA5A26A3B68
treatment provided by	ZooKeys by Pensoft
scientific name	Louisea nkongsamba
status	sp. nov.

Treatment

Louisea nkongsamba sp. nov. Figs 2d View Figure 2 , 3d View Figure 3 , 4a View Figure 4 , 5d View Figure 5 , 6d View Figure 6 , 7d View Figure 7 , 8g, h View Figure 8 , 9d View Figure 9 , 10d View Figure 10 , 11d View Figure 11 , 12d View Figure 12 , 13d View Figure 13 , 14d View Figure 14 , 15d View Figure 15

Material examined.

CAMEROON. Holotype: adult male (CW 20 mm, CL 14.85 mm, CH 8.4 mm, FW 6.6 mm), Littoral Region, Mount Nlonako Ecological Reserve (locality 1) (4.91046N, 9.976332E), 1,237 m asl, 23 May 2018, coll. P.A. Mvogo Ndongo (ZMB Crust. 31618). Paratype: adult male (CW 18.38 mm, CL 13.32 mm, CH 8.13 mm, FW 6.34 mm), Littoral Region, Mount Nlonako Ecological Reserve (locality 2) (4.91343N, 9.98500E), 1,176 m asl, 23 May 2018, coll. P.A. Mvogo Ndongo (ZMB Crust. 31620). Other material examined is listed in Table 4 View Table .

Diagnosis.

Carapace smooth, urogastric groove faint; postfrontal crest faint, complete, meeting anterolateral margin behind intermediate tooth ( Fig. 7d View Figure 7 ); exorbital, intermediate teeth large, triangular; epibranchial tooth undetectable ( Figs 4d View Figure 4 , 7d View Figure 7 ). Vertical sulcus on carapace branchiostegal wall meeting anterolateral margin at intermediate tooth ( Fig. 6d View Figure 6 ). Mandibular palp bi-segmented; terminal segment (TS) bilobed, with large distinct anterior lobe 0.8 × terminal segment length ( Fig. 15d View Figure 15 ). Third maxilliped exopod completely lacking flagellum; ischium with distinct vertical groove ( Fig. 14d View Figure 14 ). Episternal sulci s4/e4, s5/e5, s6/e6, s7/e7 complete ( Fig. 5d View Figure 5 ). Major cheliped dactylus relatively stout, straight, not arched, enclosing long thin interspace when closed, with small distal tooth ( Fig. 8g View Figure 8 ); propodus of major cheliped with three large teeth (proximal, medial, distal) ( Fig. 8g View Figure 8 ); cheliped carpus inner margin with large, broad pointed distal tooth, robust subequal proximal tooth ( Fig. 10d View Figure 10 ); cheliped merus medial inferior margin with large jagged distal tooth followed by several distinct smaller teeth ( Fig. 9d View Figure 9 ). G1TA short (TA/SS 0.22), directed outwards at 45° angle to longitudinal axis of G1SS, with distinct longitudinal groove on ventral face, proximally distinctly broad, abruptly narrow, slim and tube-like at distal two-thirds ( Figs 11d View Figure 11 , 12d View Figure 12 ). G1SS tapering slightly from broad basal margin to relatively wide distal margin (0.5 × SS basal margin); dorsal face with broad dorsal membrane (maximum width 0.1 × SS length) at TA/SS junction ( Fig. 11d View Figure 11 ). G2TA long (TA/SS 0.44), flagellum-like, almost as long as G2SS ( Fig. 13d View Figure 13 ). Mature at CW 20 mm.

Description.

Carapace ovoid, moderately high (CH/FW 1.32, N = 27), wide (CW/FW 2.95, N = 27), texture smooth, urogastric groove distinct. Front wide (FW/CW 0.34, N = 27), deflexed, anterior margin straight ( Figs 2d View Figure 2 , 3d View Figure 3 , 4a View Figure 4 , 7d View Figure 7 ). Postfrontal crest faint but complete, ends meeting anterolateral margins at epibranchial teeth ( Fig. 7d View Figure 7 ); mid-groove faint, shallow; epigastric crests poorly defined ( Fig. 7d View Figure 7 ). Exorbital, intermediate teeth large, triangular, epibranchial tooth small but detectable ( Figs 4a View Figure 4 , 7d View Figure 7 ). Anterolateral margin of carapace lined by small granules ( Figs 4a View Figure 4 , 7d View Figure 7 ); posterolateral margin curving inward, continuous with anterolateral margin ( Fig. 7d View Figure 7 ); posterior carapace margin about 2/3 CW. Carapace branchiostegal wall with longitudinal, vertical sutures dividing sidewall into three parts ( Fig. 6d View Figure 6 ). Longitudinal sulcus beginning at respiratory opening, curving backward across sidewall, dividing suborbital- and subhepatic regions from pterygostomial region ( Fig. 6d View Figure 6 ); vertical sulcus on sidewall marked by row of granules, meeting anterolateral margin at intermediate tooth ( Fig. 6d View Figure 6 ), dividing suborbital- from subhepatic regions ( Figs 6d View Figure 6 , 7d View Figure 7 ). Sternal sulcus s2/s3, deep, ends not meeting side margins of sternum ( Fig. 5d View Figure 5 ); s3 with distinct central depression; s3/s4 reduced to two short lateral notches ( Fig. 5d View Figure 5 ). Episternal sulci s4/e4, s5/e5, s6/e6, s7/e7 complete ( Fig. 5d View Figure 5 ). Mandibular palp bi-segmented; terminal segment (TS) bilobed, with large distinct anterior lobe 0.8 × terminal segment length ( Fig. 15d View Figure 15 ). Third maxilliped ( Fig. 6d View Figure 6 ) filling entire buccal cavern, except for transversely oval efferent respiratory openings in superior lateral corners; exopod completely lacking flagellum; ischium with distinct vertical groove ( Fig. 14d View Figure 14 ).

Major cheliped dactylus relatively stout, straight, not arched enclosing long, thin interspace when closed, with small proximal tooth ( Fig. 8g View Figure 8 ); propodus of major cheliped with three large teeth (proximal, medial, distal) ( Fig. 8g View Figure 8 ); cheliped carpus inner margin with large, broad, pointed distal tooth, robust, subequal proximal tooth ( Fig. 10d View Figure 10 ). Walking legs (p2-p5 slender, p4 longest, p5 shortest; dactyli (p2-p5) tapering to point, each bearing rows of downward-pointing sharp bristles, p5 dactylus shortest ( Figs 2d View Figure 2 , 3d View Figure 3 ).

Male pleon triangular, telson (a7) with rounded distal margin ( Fig. 5d View Figure 5 ). G1TA short (TA/SS 0.22), directed outwards at 45° angle to longitudinal axis of G1SS, with distinct longitudinal groove on ventral face, proximally distinctly broad, abruptly narrow, slim and tube-like at distal two-thirds ( Figs 11d View Figure 11 , 12d View Figure 12 ). G1SS tapering slightly from broad basal margin to relatively wide distal margin (0.5 × SS basal margin); dorsal face with broad dorsal membrane (maximum width 0.1 × SS length) at TA/SS junction ( Fig. 11d View Figure 11 ). G2TA long (TA/SS 0.44), flagellum-like, almost as long as G2SS ( Fig. 13d View Figure 13 ).

Color in life.

Specimens of L. nkongsamba sp. nov. have a dark brown or green carapace and walking legs.

Type locality.

Nlonako Wildlife Reserve, Nkongsamba, littoral region of Cameroon.

Etymology.

The new species is named for Nkongsamba, the closest town to the type locality. The species epithet is a noun in apposition.

Habitat.

L. nkongsamba sp. nov. is known only from Nlonako Wildlife Reserve, one of the threatened tropical rainforest habitats in the littoral region of Cameroon.

Remarks.

L. nkongsamba sp. nov. possesses numerous characters that link it to L. edeaensis , L. balssi , and L. yabassi sp. nov. Differences between these species are discussed below under general remarks.