Research Article |
Corresponding author: Pierre A. Mvogo Ndongo ( mpierrearmand@yahoo.fr ) Academic editor: Sammy De Grave
© 2019 Pierre A. Mvogo Ndongo, Thomas von Rintelen, Neil Cumberlidge.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Mvogo Ndongo PA, von Rintelen T, Cumberlidge N (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: 135-164. https://doi.org/10.3897/zookeys.881.36744
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The taxonomy of the freshwater crab genus Louisea Cumberlidge, 1994, is reviewed based on type material and newly obtained specimens from three different localities in southwestern Cameroon. The genus is endemic to Cameroon and previously included two species: L. edeaensis (Bott, 1969) (type species) from Lake Ossa wetland complex (altitudes below 400 m asl) and L. balssi (Bott, 1959) from Kumba and Mt. Manengouba (altitudes above 1300 m asl). Here two new species of Louisea are described based on morphological and/or genetic data: L. nkongsamba sp. nov. from the Nlonako Ecological Reserve (1000–1400 m asl) in the sub-montane zone and L. yabassi sp. nov. from Yabassi in the lowlands. A redescription and amended diagnostic features of L. edeaensis and L. balssi are provided, and the genus diagnosis is updated to accommodate all four species. An identification key is also provided for the species of Louisea. A tree of phylogenetic relationships based on three mtDNA loci (COI, 12S rRNA, and 16S rRNA) supports the taxonomic revision, and indicates speciation of Louisea species along an altitudinal gradient, but further phylogenetic analyses are needed to understand whether this can lend support to the hypothesis that there is a montane centre of speciation along the Cameroon Volcanic Line. The phylogenetic tree also shows that Buea Cumberlidge, Mvogo Ndongo, Clark & Daniels, 2019 and Potamonemus Cumberlidge & Clark, 1992 are sister genera that may be derived from the Louisea lineage.
Cameroon, Crustacea, identification key, new species, phylogeny, Potamoidea, redescription, taxonomic revision
The freshwater crab genus Louisea Cumberlidge, 1994, was established by
The rediscoveries of L. edeaensis and L. balssi prompted renewed extensive systematic surveys of the lowland and upland zones in the tropical rainforests of southwestern Cameroon in 2017 and 2018, which resulted in the recognition of a new species of Louisea from the submontane zone of Mt. Nlonako (1000–1400 m asl). This new species is described here based on morphological and genetic data. A second new species of Louisea is also recognised from Yabassi in the lowlands of southwestern Cameroon based on the re-examined specimens from the Museum für Naturkunde, Berlin, Germany (
A series of field surveys of freshwater decapods undertaken in southwestern Cameroon from 2015 to 2018 focused on biodiversity hotspots that had been previously identified in 2011 by Conservation International for other freshwater taxa (Fig.
All measurements (in mm) were taken with digital callipers. The terminology used follows
The following abbreviations are used:
a pleonal (abdominal) segment or pleomere;
a5/a6 sulci between adjacent pleomeres;
asl above sea level;
CW carapace width measured at widest point;
CL carapace length measured along medial line from anterior to posterior margin;
CH carapace height measured at maximum height of cephalothorax;
e episternite;
FW front width measured along anterior frontal margin between inner angles of orbits;
G1 male first gonopod;
G2 male second gonopod;
p2–p5 pereiopods 2–5 or walking legs 1–4;
SS subterminal segment of G1 or G2;
s4/e4 (s4/e4, s5/e5, s6/e6, s7/e7) episternal sulci between adjacent thoracic sternites and episternites;
s thoracic sternite;
s1/s2 (s1/s2, s2/s3, s4/s5, s5/s6, s6/s7) sternal sulci between adjacent thoracic sternites;
TA terminal article of G1 or G2;
TS terminal segment of mandibular palp.
Genomic DNA was extracted from a tissue sample of up to 25 mg cut from the pereiopod muscle of 70% ethanol-preserved specimens using the Qiagen DNeasy Blood & Tissue kit.
Polymerase chain reaction (PCR) was used to amplify three mitochondrial gene fragments, a ~ 638 bp region of the 16S ribosomal RNA gene (16S) using primers 16L29 and 16HLeu or 16H10 (
PCR products were sent to Macrogen Europe for purification and cycle sequencing of both strands of each gene. The sequences obtained were proofread manually using Chromas and aligned with Bioedit. Results from these genes were concatenated into a single alignment that was then converted into a Nexus file with FaBox (
Species of Louisea, Buea, Potamonemus and outgroups included in the molecular analyses. The newly-presented data are given in bold.
Species | Locality | Museum number | Reference study | GenBank accession number | ||
CO1 | 12S rRNA | 16S rRNA | ||||
L. nkongsamba sp. nov. | Nlonako |
|
Present | MN188072 | MN217386 | MN217393 |
L. nkongsamba sp. nov. | Nlonako |
|
Present | MN188065 | MN217387 | MN217394 |
L. balssi (CW 16.2 mm) | Manengouba |
|
Present | MN188071 | MN217385 | MN217392 |
L. balssi (CW 14.8 mm) | Manengouba |
|
Present | MN188070 | MN217384 | MN217391 |
L. edeaensis (CW 17.5 mm) | Lake Ossa | LZUY 15-3 (T351-30) |
|
KY964474 | KY964479 | KY964472 |
L. edeaensis (CW 16.15 mm) | Lake Ossa |
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Present | MN188068 | – | MN217395 |
Buea sp.1 | N.P. Korup |
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Present | MN188069 | MN217388 | MN217396 |
Buea sp.2 | N.P. Bakossi |
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Present | MN188066 | MN217389 | MN217397 |
B. asylos | Buea and Kumba |
|
|
KP640489 | KP640410 | KP640453 |
Potamonemus sp. | N.P. Bakossi |
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Present | MN188067 | MN217390 | MN217398 |
P. mambilorum | southwest Cameroon |
|
|
– | KP640409 | KP640452 |
P. sachsi | southwest Cameroon | NMU09.04.1983 |
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– | AY803490 | AY803530 |
Afrithelphusa monodosa | Guinea |
|
|
KP640469 | KP640386 | KP640430 |
Globonautes macropus | Guinea |
|
|
– | KP640391 | KP640435 |
Family Potamonautidae Bott, 1970
Subfamily Potamonautinae Bott, 1970
Globonautes
Louisea
Globonautes macropus edeaensis Bott, 1969, by original designation; gender feminine.
Amended from
Four species of Louisea endemic to southwestern Cameroon, whole animal, dorsal view. a Largest adult male (CW 17.5 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, whole animal, dorsal view. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, carapace, dorsal view. a Largest adult male, holotype (CW 20.0 mm) of L. nkongsamba sp. nov. from Mt. Nlonako (
Louisea is endemic to southern Cameroon (
The bilobed terminal segment of the mandibular palp of Louisea is unusual, and it sets this genus apart from most genera in the Potamonautinae that typically possess a simple mandibular palp (i.e., with no additional anterior lobe) (
The lack of a flagellum on the exopod of the third maxilliped in Louisea is rarely seen in other species of the Potamonautinae, and most of the members of this subfamily typically possess a long flagellum on the third maxilliped exopod (
Globonautes macropus edeaensis
Louisea edeaensis
CAMEROON. Holotype: adult male (CW 22.5 mm), Edea, Jan 1910, coll. Riggenbach (
Morphometric analysis and collection data of specimens (N = 22) of Louisea edeaensis from Cameroon (Lake Ossa; 3°48'56.1"N, 10°03'18.5"E; 90 m a.s.l.). All measurements are given in mm.
Specimens | CW | CL | CH | FW | CW/FW | CL/FW | CH/FW | FW/CL | Coll. Date | Museum |
1 ad♂ | 17.5 | 13.5 | 6.8 | 5.8 | 3.01 | 2.32 | 1.17 | 0.43 | P.A.M.N 10.07. 15 |
|
2 ad♂ | 16.15 | 12.70 | 7.80 | 5.10 | 3.17 | 2.49 | 1.53 | 0.40 | P.A.M.N 15.01. 16 |
|
3 ad♂ | 15.60 | 13.1 | 7.90 | 4.80 | 3.25 | 2.73 | 1.64 | 0.37 | P.A.M.N 15.01. 16 | IFAS-001 |
4 ad♂ | 14 | 11.03 | 6.5 | 4.5 | 3.11 | 2.51 | 1.44 | 0.39 | P.A.M.N 15.01. 16 |
|
5 ad♂ | 15.35 | 12.15 | 8.30 | 5 | 3.07 | 2.43 | 1.66 | 0.41 | P.A.M.N 10.07. 15 |
|
6 ad♀ | 19.90 | 15.2 | 7.7 | 5.9 | 3.37 | 2.57 | 1.30 | 0.38 | P.A.M.N 10.07. 15 | LZUY 15-2 (IFAS-002) |
7 ad ♀ | 17.5 | 13.30 | 6.6 | 5.3 | 3.30 | 2.50 | 1.24 | 0.39 | P.A.M.N 11.11. 16 | LZUY 15-2 (IFAS-002) |
8 ad♀ | 17.0 | 13.2 | 6.30 | 5.2 | 3.26 | 2.53 | 1.21 | 0.39 | P.A.M.N 11.11. 16 | LZUY 15-2 (IFAS-002) |
9 ad♀ | 14.80 | 11.30 | 7.2 | 4.9 | 3.02 | 2.30 | 1.46 | 0.43 | P.A.M.N 15.01. 16 | LZUY 15-3 (T351-30) |
10 ad ♀ | 17.30 | 13.80 | 9.80 | 5.90 | 2.90 | 2.33 | 1.66 | 0.42 | P.A.M.N 10.07. 15 | LZUY 15-2 (IFAS-002) |
11 ad♀ | 14.6 | 11.2 | 7.1 | 4.90 | 2.97 | 2.28 | 1.44 | 0.43 | P.A.M.N 15.01. 16 | LZUY 15-1 (IFAS-003) |
12 ad ♀ | 18.90 | 13.89 | 10.50 | 6.01 | 3.14 | 2.31 | 1.74 | 0.43 | P.A.M.N 15.01. 16 |
|
13 ad♀ | 14.10 | 11.20 | 7 | 4.7 | 3.0 | 2.38 | 1.48 | 0.41 | P.A.M.N 10.07. 15 | IFAS-004 |
14 sd♀ | 13 | 10.50 | 5.80 | 4 | 3.25 | 2.62 | 1.45 | 0.38 | P.A.M.N 10.07. 15 | LZUY 15-3 (IFAS-005) |
15 sd♂ | 11.80 | 10.09 | 5.80 | 4 | 2.95 | 2.52 | 1.45 | 0.39 | P.A.M.N 11.11. 16 | IFAS-004 |
16 sd♂ | 11.70 | 9.89 | 6 | 4 | 2.92 | 2.47 | 1.5 | 0.40 | P.A.M.N 11.11. 16 | IFAS-004 |
17 sd♂ | 12.40 | 9.80 | 5.7 | 4 | 3.1 | 2.45 | 1.42 | 0.40 | P.A.M.N 11.11. 16 | IFAS-004 |
18 sd♂ | 12.00 | 9.5 | 5.6 | 4 | 3 | 2.37 | 1.4 | 0.42 | P.A.M.N 10.07. 15 | LZUY 15-1 (IFAS-003) |
19 sd♀ | 13.60 | 10.01 | 6.80 | 4.15 | 3.27 | 2.41 | 1.63 | 0.41 | P.A.M.N 11.11. 16 | IFAS-004 |
20 sd♀ | 12.80 | 9.8 | 6 | 4 | 3.2 | 2.45 | 1.5 | 0.40 | P.A.M.N 11.11. 16 | IFAS-004 |
21 sd♀ | 11.60 | 10 | 5.5 | 3.8 | 3.05 | 2.63 | 1.44 | 0.38 | P.A.M.N 11.11. 16 | IFAS-004 |
22 sd♀ | 11.01 | 9.50 | 5.40 | 3.8 | 2.89 | 2.5 | 1.42 | 0.40 | P.A.M.N 11.11. 16 | LZUY 15-4 (IFAS-005) |
Mean | 14.02 | 11.07 | 6.36 | 4.51 | 2.96 | 2.45 | 1.41 | 0.40 | – | – |
Amended from
Amended from
Four species of Louisea endemic to southwestern Cameroon, thoracic sternites (s1–s8) and pleonal segments (a4–a7). a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, whole animal, ventral view. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to Southwestern Cameroon, carapace, frontal view. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Male chelipeds greatly unequal, right cheliped larger than left cheliped (Figs
Four species of Louisea endemic to Southwestern Cameroon, frontal view of right and left chela. a, b Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, right cheliped merus. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Male pleon triangular, telson (a7) rounded at distal margin (Fig.
Four species of Louisea endemic to southwestern Cameroon, right cheliped carpus. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, right G1 dorsal view (a–c), left G1 dorsal view (d). a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, right G1 ventral view (a–c), left G1 ventral view (d). a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
Four species of Louisea endemic to southwestern Cameroon, G2 a second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
The description and diagnosis of L. edeaensis by
Globonautes balssi
Globonautes macropus balssi
Louisea balssi
CAMEROON. Holotype: juvenile male (CW 12.5 mm), Barombi Mbo [formerly Johann Albrechtshöhe (Government Station Johann Albrecht Mountain), Barombi Station] (4.666686N, 9.392042E), 323 m asl, 10 September 1909, coll. Carl Rathke (ZIM K3506). Paratypes: 3 adult females (CWs 22.0, 21.0, 21.0 mm) (ovigerous), subadult female (CW 13.5 mm), Barombi Mbo [formerly Johann Albrechtshöhe (Government Station Johann Albrecht Mountain), Barombi Station] (4.666686N, 9.392042E), 323 m asl, 10 September 1909, coll. Carl Rathke (
Morphometric analysis and collection data of specimens (N = 8) of Louisea balssi from Cameroon (S.R, Man. Man’s Crater Lake; 5°01'56.9"N, 9°49'37.8"E; 1,958 m a.s.l.). All measurements are given in mm.
Specimens | CW | CL | CH | FW | CW/FW | CL/FW | CH/FW | FW/CL | Coll. Date | Museum |
---|---|---|---|---|---|---|---|---|---|---|
1 adult ♂ | 16.2 | 11.8 | 7.1 | 5.5 | 2.94 | 2.14 | 1.29 | 0.46 | P.A.M.N 14.03.17 |
|
2 adult ♂ | 14.8 | 10.7 | 6.1 | 5.1 | 2.90 | 2.09 | 1.19 | 0.47 | P.A.M.N 14.03.17 |
|
3 adult ♂ | 14.3 | 10.5 | 6.0 | 5.0 | 2.86 | 2.10 | 1.20 | 0.47 | P.A.M.N 14.03.17 | LZUY 20 (IFAS-005) |
4 adult ♂ | 13.3 | 9.7 | 5.6 | 4.6 | 2.89 | 2.11 | 1.21 | 0.47 | P.A.M.N 14.03.17 | LZUY 20 (IFAS-005) |
5 adult ♀ | 14.8 | 10.9 | 6.4 | 4.7 | 3.14 | 2.31 | 1.36 | 0.43 | P.A.M.N 14.03.17 |
|
6 subadult ♂ | 11.1 | 8.6 | 4.8 | 4.2 | 2.64 | 2.04 | 1.14 | 0.48 | P.A.M.N 14.03.17 | LZUY 20 (IFAS-005) |
7 subadult ♂ | 12.7 | 9.2 | 5.7 | 4.3 | 2.95 | 2.13 | 1.32 | 0.46 | P.A.M.N 14.03.17 | LZUY 20 (IFAS-005) |
8 subadult ♀ | 11.2 | 8.2 | 4.8 | 4.0 | 2.80 | 2.05 | 1.20 | 0.48 | P.A.M.N 14.03.17 | LZUY 20 (IFAS-005) |
Mean | 13.6 | 10 | 5.8 | 4.7 | 2.89 | 2.12 | 1.23 | 0.47 | – | – |
Amended from
A re-description of L. balssi is given in
Specimens of L. balssi are known only from Kumba and Mt. Manengouba in southwestern Cameroon. The morphological features of L. balssi are mainly defined from the adult male specimens collected from Mt. Manengouba (
Four species of Louisea endemic to southwestern Cameroon, left third maxilliped. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
CAMEROON. Holotype: adult male (CW 18.11 mm, CL 12.78 mm, CH 8.30 mm, FW 6.29 mm; CW/FW 2.88, CL/FW 2.03, CH/FW 1.32, FW/CL 0.49, FW/CW 0.34), Yabassi, 10 September 1909, coll. Riggenbach (
Carapace smooth, urogastric groove faint; postfrontal crest distinct, prominent, complete, meeting anterolateral margin behind intermediate tooth (Fig.
Carapace ovoid, flat (CH/FW 1.28, N = 2), wide (CW/FW 2.8), smooth, urogastric groove distinct; front wide (FW/CW 0.35, N = 2), deflexed, anterior margin straight; postfrontal crest distinct, prominent, completely crossing carapace, meeting anterolateral margin of carapace behind intermediate tooth (Fig.
Mandibular palp bi-segmented; terminal segment (TS) bilobed, with large distinct anterior lobe 0.6 × terminal segment length (Fig.
Male chelipeds unequal, right chelipeds larger than left cheliped; fingers slim, elongated. Right (major) cheliped dactylus relatively stout, straight, with five large teeth (one small distal, two large medial, two small proximal); fixed finger (pollex) with five large teeth (one distal, four proximal) (Fig.
Male pleon triangular, sides not indented with small setae; telson (a7) rounded at distal margin (Fig.
Unknown.
Yabassi, littoral region of Cameroon.
The new species is named for Yabassi in south-western Cameroon, where it was collected in 1909. The species epithet is a noun in apposition.
Louisea yabassi sp. nov. is known only from Yabassi, a humid area of the coastal rain forest of southwestern Cameroon. It is possible that this species is also present in the Ebo forest near Yabassi, which is one of the largest remaining tracts of lowland and submontane rainforest in the area.
Characters of the carapace and chelipeds of adult male specimens from Yabassi assigned to L. edeaensis by
Four species of Louisea endemic to southwestern Cameroon, ventral view of right mandible. a Second largest adult male (CW 16.1 mm) of L. edeaensis from Lake Ossa wetland complex (
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 (
Morphometric analysis and collection data of specimens (N = 27) of Louisea nkongsamba sp. nov. from Cameroon. All measurements are given in mm.
Specimens | CW | CL | CH | FW | CW/FW | CL/FW | CH/FW | FW/CL | Coll. Date | Museum |
1 ad ♂1 | 20 | 14.85 | 8.4 | 6.6 | 3.03 | 2.25 | 1.27 | 0.44 | P.A.M.N 23.05.18 |
|
2 ad ♂2 | 18.38 | 13.32 | 8.13 | 6.34 | 2.89 | 2.1 | 1.28 | 0.47 | P.A.M.N 25.05.18 |
|
3 ad ♂1 | 18.36 | 13.30 | 8.12 | 6.17 | 2.97 | 2.15 | 1.31 | 0.46 | P.A.M.N 23.05.18 |
|
4 ad ♂3 | 17.01 | 12.30 | 7.53 | 5.56 | 3.05 | 2.21 | 1.35 | 0.45 | P.A.M.N 26.05.18 |
|
5 ad ♂3 | 17.27 | 12.80 | 7.55 | 5.50 | 3.14 | 2.32 | 1.36 | 0.42 | P.A.M.N 26.05.18 |
|
6 ad ♂4 | 18.40 | 13.52 | 8.56 | 5.90 | 3.11 | 2.29 | 1.45 | 0.32 | P.A.M.N 27.05.18 |
|
7 ad ♂4 | 17.61 | 13.15 | 7.80 | 6.08 | 2.89 | 2.16 | 1.28 | 0.34 | P.A.M.N 27.05.18 |
|
8 ad ♂4 | 17.37 | 12.89 | 7.73 | 5.60 | 3.10 | 2.30 | 1.38 | 0.43 | P.A.M.N 27.05.18 |
|
9 ad ♂1 | 18.05 | 12.84 | 8 | 6.16 | 2.93 | 2.08 | 1.29 | 0.47 | P.A.M.N 25.05.18 |
|
10 ad ♂1 | 16.75 | 12.50 | 7.71 | 5.77 | 2.90 | 2.16 | 1.33 | 0.46 | P.A.M.N 23.05.18 |
|
11 ad ♂1 | 16.01 | 11.68 | 7.04 | 5.31 | 3.01 | 2.19 | 1.32 | 0.45 | P.A.M.N 23.05.18 |
|
12 ad ♂1 | 16.90 | 12.20 | 7.81 | 5.32 | 3.17 | 2.29 | 1.46 | 0.43 | P.A.M.N 23.05.18 |
|
13 ad ♂1 | 15.24 | 11.47 | 6.41 | 5.42 | 2.81 | 2.11 | 1.18 | 0.47 | P.A.M.N 23.05.18 |
|
14 ad ♂2 | 15.55 | 11.60 | 6.93 | 5.40 | 2.87 | 2.14 | 1.28 | 0.46 | P.A.M.N 25.05.18 |
|
15 ad ♂2 | 16.50 | 12.19 | 7.47 | 5.60 | 2.94 | 2.17 | 1.33 | 0.45 | P.A.M.N 25.05.18 |
|
16 ad ♀2 | 19.72 | 14.76 | 9.12 | 7.03 | 2.80 | 2.1 | 1.29 | 0.47 | P.A.M.N 25.05.18 | IFAS-005 |
17 ad ♀2 | 17.10 | 13.03 | 8.28 | 5.96 | 2.86 | 2.18 | 1.38 | 0.45 | P.A.M.N 25.05.18 | IFAS-005 |
18 ad ♀1 | 16.15 | 11.66 | 7.10 | 5.62 | 2.87 | 2.07 | 1.26 | 0.48 | P.A.M.N 23.05.18 | IFAS-005 |
19 ad ♀2 | 15.04 | 11.10 | 6.86 | 5 | 3 | 2.22 | 1.37 | 0.45 | P.A.M.N 25.05.18 | IFAS-005 |
20 ad ♀2 | 14.73 | 10.80 | 6.25 | 4.80 | 3.06 | 2.25 | 1.30 | 0.44 | P.A.M.N 25.05.18 | IFAS-005 |
21 ad ♀2 | 14.56 | 10.9 | 6.08 | 5.15 | 2.82 | 2.11 | 1.18 | 0.47 | P.A.M.N 25.05.18 | IFAS-005 |
22 sd ♂2 | 13.49 | 10.33 | 6.20 | 4.45 | 3.03 | 2.32 | 1.39 | 0.43 | P.A.M.N 25.05.18 | IFAS-006 |
23 sd ♂2 | 13.76 | 10.54 | 5.85 | 4.35 | 3.16 | 2.42 | 1.34 | 0.41 | P.A.M.N 25.05.18 | IFAS-006 |
24 sd ♂2 | 13.33 | 10.30 | 6.10 | 4.25 | 3.13 | 2.42 | 1.43 | 0.41 | P.A.M.N 25.05.18 | IFAS-006 |
25 sd ♂2 | 12.87 | 10.08 | 5.86 | 4.17 | 3.08 | 2.41 | 1.40 | 0.41 | P.A.M.N 25.05.18 | IFAS-006 |
26 sd ♂2 | 13.14 | 10.09 | 5.91 | 4.60 | 2.85 | 2.19 | 1.28 | 0.45 | P.A.M.N 25.05.18 | IFAS-006 |
27 sd ♂2 | 12.91 | 9.94 | 5.64 | 4.70 | 2.74 | 2.11 | 1.20 | 0.47 | P.A.M.N 25.05.18 | IFAS-006 |
Mean | 16.15 | 12.00 | 7.20 | 5.46 | 2.95 | 2.19 | 1.32 | 0.45 | – | – |
Carapace smooth, urogastric groove faint; postfrontal crest faint, complete, meeting anterolateral margin behind intermediate tooth (Fig.
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
Major cheliped dactylus relatively stout, straight, not arched enclosing long, thin interspace when closed, with small proximal tooth (Fig.
Male pleon triangular, telson (a7) with rounded distal margin (Fig.
Specimens of L. nkongsamba sp. nov. have a dark brown or green carapace and walking legs.
Nlonako Wildlife Reserve, Nkongsamba, littoral region of Cameroon.
The new species is named for Nkongsamba, the closest town to the type locality. The species epithet is a noun in apposition.
L. nkongsamba sp. nov. is known only from Nlonako Wildlife Reserve, one of the threatened tropical rainforest habitats in the littoral region of Cameroon.
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.
ML tree topology for the freshwater crab taxa from Cameroon included in this study derived from mtDNA sequences corresponding to three loci (partial 16S rRNA, COI and 12S rRNA genes). BI and ML statistical values (%) on the nodes indicate posterior probabilities and bootstrap support, respectively.
The generic characters of Louisea proposed by
Characters | L. nkongsamba sp. nov. | L. yabassi sp. nov. | L. balssi | L. edeaensis |
---|---|---|---|---|
Major cheliped dactylus shape | Stout, straight (Fig. |
Stout, straight (Fig. |
Slender, highly arched (Fig. |
Stout, straight (Fig. |
Major cheliped propodus dentition | 3 large teeth (Fig. |
5 large teeth (Fig. |
2 large proximal teeth (Fig. |
4 large teeth (Fig. |
Cheliped carpus inner margin teeth | Distal larger than proximal (Fig. |
Both large and pointed (Fig. |
Both large and pointed (Fig. |
Distal larger than proximal (Fig. |
Intermediate tooth between exorbital and epibranchial teeth | Large and triangular (Figs |
Large and triangular (Figs |
Faint, barely detectable (Figs |
Small but distinct (Figs |
Postfrontal crest | Faint (Figs |
Prominent, clearly defined (Figs |
Faint (Figs |
Faint (Figs |
Sternal sulcus s2/s3 | Deep, ends not meeting side margins of sternum (Figs |
Deep, ends meeting side margins of sternum (Figs |
Deep, ends meeting side margins of sternum (Figs |
Faint and shallow, ends meeting side margins of sternum (Figs |
Sternal segment s3 | With distinct central depression (Figs |
No depression (Figs |
No depression (Figs |
No depression (Figs |
Size of anterior lobe on terminal segment (TS) of mandibular palp | Large (0.8× TS length) (Fig. |
Medium (0.6× TS length) (Fig. |
Small (0.5× TS length) (Fig. |
Medium (0.6× TS length) (Fig. |
G1 TA length | Short (0.22× G1 length) (Fig. |
Medium (0.27× G1 length) (Fig. |
Medium (0.28× G1 length) (Fig. |
Medium (0.29× G1 length) (Fig. |
The highlands of southwestern Cameroon are part of the continental segment of the Cameroon Volcanic Line (CVL) that includes Mount Cameroon, Mt. Manengouba, Mt. Nlonako, Mt. Lefo, Mt. Oku, and the Ngaoundere Plateau (
Our phylogenetic analyses (Fig.
1 | Postfrontal crest prominent, clearly defined (Figs |
L. yabassi sp. nov. |
– | Postfrontal crest faint (Figs |
2 |
2 | Dactylus of male major cheliped relative slender, highly arched (Fig. |
L. balssi |
– | Dactylus of male major cheliped relative stout, straight (Fig. |
3 |
3 | Sternal segment s3 lacking central depression, sternal sulcus s2/s3 relatively shallow, ends meeting side margins of sternum (Figs |
L. edeaensis |
– | Sternal segment s3 with distinct central depression, sternal sulcus s2/s3 deep, ends not meeting side margins of sternum (Figs |
L. nkongsamba sp. nov. |
We thank the Rufford Small Grant Foundation for funding the fieldwork in the South and Southwestern Regions of Cameroon, and the Museum für Naturkunde, Berlin (