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
Author
Mvogo Ndongo, Pierre A.
Author
von Rintelen, Thomas
Author
Cumberlidge, Neil
text
ZooKeys
2019
881
135
164
http://dx.doi.org/10.3897/zookeys.881.36744
journal article
http://dx.doi.org/10.3897/zookeys.881.36744
1313-2970-881-135
B058CA156A3D41A19ADFD00384234D8E
16F69FEA95835AE5BF6B9C34F83E49D7
Louisea edeaensis (Bott, 1969)
Figs 2a
,
3a
,
4c
,
5a
,
6a
,
7a
,
8a, b
,
9a
,
10a
,
11a
,
12a
,
13a
,
14a
,
15a
Globonautes macropus edeaensis
Bott 1969
: 360;
1970
: 24, pl. 1, figs 3-5, pl. 26, fig. 8;
Cumberlidge 1987
: 2215, table 2.
Louisea edeaensis
Cumberlidge 1994
: 124, fig. 1, table 1; 1997: 577; 1999: 227, 5300, 54-57, figs 46F, 47E, 48E, 49F, 51F, 52F, 53DD, 54-57, 62F, 68F, table IX, plate 3;
Ng et al. 2008
: 169 (list);
Cumberlidge et al. 2009
: 6;
Mvogo Ndongo et al. 2017a
: 273, figs 1-3; 2017c: 440, fig. 1.
Material examined.
CAMEROON. Holotype: adult male (CW 22.5 mm), Edea, Jan 1910, coll. Riggenbach (ZSBS 1118/1). Adult male, 2 adult females (CWs 19.4, 17.5 mm), Yaounde, 1907, coll. Haberer (NHMW 1877). See Table
2
for details of the material examined from Lake Ossa.
Table 2.
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 |
ZMB Crust. 26930 |
| 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 |
ZMB Crust. 30335 |
| 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 |
ZMB Crust. 30335 |
| 5 ad♂ |
15.35 |
12.15 |
8.30 |
5 |
3.07 |
2.43 |
1.66 |
0.41 |
P.A.M.N 10.07. 15 |
ZMB Crust. 30319 |
| 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 |
ZMB Crust. 30335 |
| 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
|
- |
- |
Diagnosis.
Amended from
Cumberlidge (1994
,
1999
);
Mvogo Ndongo et al. (2017a)
. Carapace smooth, urogastric groove faint (
Figs 2a
,
3a
,
4c
). Postfrontal crest faint, complete, meeting anterolateral margin behind intermediate tooth (
Fig. 7a
). Exorbital, intermediate teeth small, low, distinct (
Figs 2a
,
3a
,
4c
,
7a
). Third maxilliped ischium with distinct vertical groove (
Fig. 14a
). Terminal segment (TS) of mandibular palp bilobed, with large distinct anterior lobe (0.6
x
terminal segment length) (
Fig. 15a
). Major cheliped dactylus relatively stout, straight, with two large teeth (one proximal, one medial) (
Fig. 8a
); cheliped propodus with four large teeth (three proximal, one distal); cheliped carpus inner margin with long, broad distal tooth followed by slim, smaller proximal tooth (
Fig. 10a
). G1TA short (TA/SS = 0.3), directed outward at 45° angle to longitudinal axis of G1SS, proximally broad, distal two-thirds narrowing abruptly to form slim tube (
Figs 11a
,
12a
). G1SS tapering slightly from broad basal margin to relatively wide distal margin (0.6
x
SS basal margin), dorsal face with broad dorsal membrane (maximum width 0.1
x
SS length) at TA/SS junction (
Fig. 11a
). G2TA long (TA/SS = 0.40), flagellum-like, almost as long as G2SS (
Fig. 13a
). Mature between CWs 14-23 mm.
Re-description.
Amended from
Cumberlidge (1994
,
1999
). Carapace ovoid, high, slightly arched (CH/FW 1.41,
N
= 22), wide (CW/FW 3.14,
N
= 22), smooth; postfrontal crest poorly defined, completely crossing carapace, meeting anterolateral margins of carapace behind intermediate tooth (
Fig. 7a
); mid-groove broad, shallow, epigastric crests poorly defined (
Fig. 7a
); external orbital tooth small, low; epibranchial tooth reduced to granule, almost undetectable (
Figs 4a
,
7a
); intermediate tooth on anterolateral margin between external orbital, epibranchial teeth small but detectable (
Figs 4a
,
7a
); anterolateral margin lined by small granules (
Figs 4a
,
7a
); posterolateral margin continuous with anterolateral margin, curving inward; posterior margin of carapace wide (2/3 CW). Carapace branchiostegal wall with 2 sutures dividing it into 3 parts (
Fig. 6a
); longitudinal suture beginning at respiratory opening dividing suborbital, subhepatic regions from pterygostomial region (
Fig. 6a
); vertical suture beginning at epibranchial tooth curving sharply down to meet longitudinal suture, marked by row of granules (
Figs 6a
,
7a
). Sternal sulcus s2/s3, deep, complete, s3 lacking depression (
Fig. 5a
); s3/s4 reduced to 2 short, distinct notches on each side of sternum (
Fig. 5a
); episternal sulci s4/e4, s5/e5, s6/e6 faint or missing, s7/e7 complete (
Fig. 5a
). Mandibular palp 2 segmented; terminal segment (TS) bilobed, anterior lobe 0.6
x
length of terminal segment (
Fig. 15a, d
). Third maxillipeds (
Fig. 6a
) filling entire buccal cavern, except for transversely oval efferent respiratory openings in superior lateral corners; ischium with distinct vertical groove (
Fig. 14a
); exopod lacking flagellum (
Fig. 14a
).
Figure 5.
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 (ZMB Crust. 30335)
b
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319) (missing left p5) ('
Mvogo Ndongo et al. 2018
: fig. 2
c'
, www.mapress.com/j/zt)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 12.42 mm (
a
), 9 mm (
b
), 8.30 mm (
c
), 17 mm (
d
).
Figure 6.
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 (ZMB Crust. 30335)
b
second largest adult male (CW 14.8 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 11.63 mm (
a
), 9.61 mm (
b
), 9.50 mm (
c
), 11.60 mm (
d
).
Figure 7.
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 (ZMB Crust. 30335)
b
second largest adult male (CW 14.8 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 7.20 mm (
a
), 6.60 mm (
b
), 8.06 mm (
c
), 8.70 mm (
d
).
Male chelipeds greatly unequal, right cheliped larger than left cheliped (
Figs 3a
,
6a
). Dactylus, propodus of right (major) cheliped slim, elongated; fixed finger (propodus) with 4 large pointed teeth (3 proximal, 1 distal); movable finger (dactylus) relatively stout, straight, with 2 large teeth (1 proximal, 1 medial) (
Fig. 8a
). Dactylus, propodus of left (minor) cheliped slender, with small teeth on occluding margins (
Figs 2a
,
3a
). Medial inferior margin of cheliped merus with large jagged distal tooth angled outward at 90°, followed by numerous distinct smaller teeth decreasing in size proximally (
Figs 6a
,
9a
; see
Mvogo Ndongo et al. 2017a
: fig. 1B). Cheliped carpus inner margin with 2 large pointed teeth, distal tooth long, broad with pointed tip; proximal tooth longer than distal tooth (
Fig. 10a
). 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 2a
,
3a
).
Figure 8.
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 (ZMB Crust. 30335)
c, d
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319) (missing left p5) ('
Mvogo Ndongo et al. 2018
: fig. 3a,
b'
, www.mapress.com/j/zt)
e, f
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
g, h
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 5 mm (
a, c, e, g
), 2 mm (
b, d, f
), 10 mm (
h
).
Figure 9.
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 (ZMB Crust. 30335)
b
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319) (missing left p5) ('
Mvogo Ndongo et al. 2018
: fig. 3
d'
, www.mapress.com/j/zt)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 5 mm (
a, c
), 2 mm (
b
), 10 mm (
d
).
Male pleon triangular, telson (a7) rounded at distal margin (
Fig. 5a
). G1TA short (TA/SS 0.3), directed outward at 45° angle to longitudinal axis of G1SS, proximally distinctly broad, abruptly narrow, slim and tube-like at distal two-thirds (
Figs 11a
,
12a
). G1SS tapering slightly from broad basal margin to relatively wide distal margin (0.6
x
SS basal margin); dorsal face with broad dorsal membrane (maximum width 0.1
xSS
length) at TA/SS junction (
Fig. 11a
); ventral face with raised triangular flap extending halfway across segment forming roof of chamber for G2, flap tapering diagonally from broad base to narrow point at SS/TA junction (
Fig. 12a
). G2TA long (TA/SS = 0.40), flagellum-like, almost as long as G2SS (
Fig. 13a
); G2SS wide at base, tapering sharply to long, thin process with raised rim at junction with TA (
Fig. 13a
). Mature between CW 14-23 mm.
Figure 10.
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 (ZMB Crust. 30335)
b
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319) ('
Mvogo Ndongo et al. 2018
: fig. 3
c'
, www.mapress.com/j/zt)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 5 mm (
a, c
), 2 mm (
b
), 10 mm (
d
).
Figure 11.
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 (ZMB Crust. 30335)
b
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319) ('
Mvogo Ndongo et al. 2018
: fig. 5
a'
, www.mapress.com/j/zt)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 2 mm (
a, c, d
), 1 mm (
b
).
Figure 12.
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 (ZMB Crust. 30335)
b
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319) ('
Mvogo Ndongo et al. 2018
: fig. 5
b'
)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 2 mm (
a, c, d
), 1 mm (
b
).
Figure 13.
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 (ZMB Crust. 30335)
b
largest adult male (CW 16.2 mm) of
L. balssi
from
Man's
Crater Lake Manengouba (ZMB Crust. 30319)
c
adult male, holotype (CW 18.1 mm) of
L. yabassi
sp. nov. from Yabassi (ZMB Crust. 21575)
d
largest adult male, holotype (CW 20.0 mm) of
L. nkongsamba
sp. nov. from Mt. Nlonako (ZMB Crust. 31618). Scale bars: 2 mm (
a-d
).
Remarks.
The description and diagnosis of
L. edeaensis
by
Cumberlidge (1994)
was based on characters of specimens from Edea and Yabassi.
Mvogo Ndongo et al. (2017a)
updated these characters following the discovery of a large series of
L. edeaensis
from Bedimet Island in Lake Ossa in August 2015. These specimens included only one adult male that agreed well with the diagnostic characters of the holotype from Edea, and with other specimens from Yaounde and Yabassi. Nevertheless, the morphological variations raised by
Cumberlidge (1994)
that distinguished the specimens from Yabassi from those from Yaounde, Edea, and Lake Ossa still remained. The specimens of Lake Ossa examined in this study included five adult males whose morphological characters are consistent with those from Edea and Yaounde, but different from the specimens from Yabassi. This resulted in the present re-description of
L. edeaensis
. Differences between
L. edeaensis
and its congeners are given below under general remarks.