Hydrothelphusa goudoti (H. Milne Edwards, 1853 ) Cumberlidge & Sternberg, 2002

Cumberlidge, Neil & Sternberg, Richard V., 2002, The freshwater crabs of Madagascar (Crustacea, Decapoda, Potamoidea), Zoosystema 24 (1), pp. 41-79 : 56-59

Hydrothelphusa goudoti (H. Milne Edwards, 1853) n. comb.

( Figs 1D ; 3D ; 4D ; 5D ; 6D ; 7G, H ; 8D ; 9 J-M; 11D)

Thelphusa goudoti H. Milne Edwards, 1853: 212 . — A. Milne-Edwards 1869: 172, pl. 8, fig. 4a-b; 1887: 135.

Telphusa goudoti – De Man 1892: 235.

Potamon goudoti – De Man 1898: 434.

Potamon (Potamon) goudoti Rathbun, 1904: 305 , 306, fig. 34, pl. 13, fig. 10. — Balss 1929: 355.

Potamon (Geothelphusa) methueni Calman, 1913: 920 .

Bottia goudoti – Pretzmann 1961: 164, fig. 3.

Gecarcinautes goudoti — Bott 1965: 338, 339, pl. 2, figs 6, 7. — Cumberlidge 1997: 585; 1998: 209.

MATERIAL EXAMINED. — Madagascar. Road between Bombetok and Tananarive, coll. Goudot, lectotype of Thelphusa goudoti : 1 ad. cw 46, cl 33.5 mm, dried specimen ( MNHN-B 3817). — 2 dried paralectotypes, 1 ad.

cw 41, cl 30.7 mm, second specimen broken, presumed syntype, described by A. Milne-Edwards (1869) in Arch. Mus. Hist. Nat. V: 172 ( MNHN-B 3818). — Imerimandrosa, type of P. (G.) methueni ( NHM 1914.6.11.3). — Tananarive, 1 subad. cw 37 mm ( MNHN-B 5166). — Tananarive, coll. M. Catat, 3 subad. cw 29, 29.5, 40 mm ( MNHN-B 167). — 20.IV.1897, coll. Ct. Dorr, 1 subad. cw 23, cl 17 mm ( MNHN-B 26642). — Forest, Manambato Valley, 1927, coll. G. Petit, 1 subad. cw 23, cl 17 mm ( MNHN-B 26643). — Forest, Manambato Valley, North of Tsaratanana Mountains, 1 subad. cw 23.6 mm ( ZSM 1532/1). — 1911, coll. J. de Joannis, 1 ad., ovig. cw 30 mm ( MNHN-B 26644), 1 subad. cw 26, cl 18.5 mm ( MNHN-B 25733). — Lake Alaotra, North of Antananarivo (formerly Tananarive), coll. Voeltzkow, 3 ad. cw 46.8, 41,4, 32.8 mm, 1 ad. cw 31.2 ( ZSM 1532/2). — Toamasina, coll. J. Millot, 1 subad. cw 20.9 mm ( ZSM 1532/3). — Chambendiana river, 1 specimen ( ZIM K3543). — Lake Alaotra, 1 specimen ( SMF 4486). — Lake Alaotra, 1 specimen ( ZMB 13912). — Tananarive, 1 specimen ( ZMB 13911).

TYPELOCALITY. — Madagascar. Thelphusa goudoti : Madagascar, road between Bombetok and Tananarive. Potamon (Geothelphusa) methueni: Imerimandrosa.

DISTRIBUTION. — Madagascar ( Fig. 11D ). See Cumberlidge (1998) for more localities.

DIAGNOSIS. — Carapace very wide (cw/fw = 3.9), very long (cl/fw = 2.8), highly arched (ch/fw = 1.6); epigastric, postorbital crests fused forming distinct postfrontal crest, ending just before meeting anterolateral margins. Front distinctly deflexed (but not vertical); exorbital, epibranchial teeth broad, low, blunt, continuous with curve of anterolateral margin; cervical grooves long. p5 merus very short (ratio length p5 merus/cw = 0.4). Midpoint of medial fold of terminal article of gonopod 1 widened by rounded, raised lobe.

REDESCRIPTION

Carapace very wide (cw/fw = 3.9), very long (cl/fw = 2.8), highly arched (ch/fw = 1.6). Suborbital margin with faint granules. Anterior carapace regions smooth, posterolateral regions with short, faint, carinae. Semi-circular, urogastric, cardiac grooves deep; cervical grooves deep, long, not meeting postorbital crest. Epigastric, postorbital crests fused, forming distinct postfrontal crest, ending just before meeting anterolateral margins (i.e. postfrontal crest incomplete). Front distinctly deflexed (but not vertical); front with shallow indentation, margin raised, smooth. Exorbital, epibranchial teeth broad, low, blunt, continuous with curve of anterolateral margin. Anterolateral margin posterior to epibranchial tooth raised, granular. Suborbital margin faintly granulated. Suborbital, pterygostomial regions of carapace sidewall granular, subhepatic region either smooth or with faint granules.

Finger of propodus of p1 (cheliped) with three medium-sized pointed proximal teeth, one large tooth, several small teeth; dactylus with small teeth interspersed by three medium teeth. Anterior inferior margin of ischium of p1 granular, posterior inferior margin smooth. Inferior margins of merus of p1 distinctly granulated, distal margin with single large pointed tooth; superi- or surface of merus granular. Inner margin of carpus of cheliped with two teeth; first carpal tooth large, pointed; second tooth small, low; margin behind second tooth raised, smooth. Midpoint of medial fold of terminal article of gonopod 1 with distinct, rounded, raised lobe.

Size

The adult size range is from cw 40 to 46.8 mm. The carapace proportions are given in Table 3.

REMARKS

Hydrothelphusa goudoti n. comb. was the first freshwater crab to be described from Madagascar (in 1853), and it has long been recognised as a distinct species. However, the generic assignment of this species has been less stable and has been revised a number of times ( Rathbun 1904; Colosi 1920; Pretzmann 1961; Bott 1965), and is revised once again in the present study. The present reassignment of H. goudoti n. comb. to Hydrothelphusa ( Hydrothelphusinae , Potamonautidae ) is made on the basis of similarities of characters of the mandibular palp, carapace, thoracic sternum, third maxilliped, and gonopods 1 and 2 of H. goudoti n. comb., which unite this species with H. bombetokensis , H. agilis and H. madagascariensis . The distinguishing differences between H. goudoti n. comb., H. bombetokensis , H. madagascariensis and H. agilis are provided above. Hydrothelphusa goudoti n. comb. is characterized by its unusual carapace proportions: it has the widest, longest and most arched carapace of any species in this genus, and the p5 merus length/cw ratio is the shortest of any species in this genus ( Table 3).

Bott (1965) regarded P. (G.) methueni as a junior synonym of Madagapotamon ankaraharae ( Nobili, 1906) , but we can find no support for that opinion here. For example, the type of P. (G.) methueni was examined in this study and the mandibular palp is bilobed, of the kind seen in Hydrothelphusa (and is not simple, as has been reported for M. ankaraharae by Bott [1965], but see below for a different opinion). In addition, the type of P. (G.) methueni compares well with type of H. goudoti n. comb. in all important characters of the carapace, chelipeds, mouthparts, sternum and gonopods. For these reasons, P. (G.) methueni is regarded here as a junior objective synonym of H. goudoti n. comb.

Bott (1965) considered P. (G.) ankaraharae to be a species of Madagapotamon , but we do not follow this view here. The illustration of the carapace, third maxilliped, sternum and abdomen of the type of Potamon (Geothelphusa) ankaraharae provided by Nobili (1906) and reproduced in Bott (1965: fig. 9a-c) conform with characters described above for H. goudoti n. comb., and we sus- pect that P. (G.) ankaraharae should be regarded as a junior subjective synonym of H. goudoti . However, without examining the type specimen of P. (G.) ankaraharae (which has proved difficult to obtain) we have no first-hand knowledge of the characters of the mandibular palp and first gonopod of this taxon. It should be noted that the male specimen cw 28 mm (MNHN Paris, no number provided) labeled M. ankaraharae in Bott (1965: fig. 9d, e, pl. 5, figs 23-25) from Diego-Suarez (now Antsiranana) was not part of the type series, and we consider it likely that his specimen was actually misidentified, and that it may not actually be P. (G.) ankaraharae Nobili, 1906 . As such, the illustrations of gonopods 1 and 2 in Bott 1965 (fig. 9d, e) and this text description of the mandibular palp as simple, should not be regarded as those of P. (G.) ankaraharae sensu Nobili, 1906 .

The taxonomic position of Gecarcinautes Bott, 1960

The genus Gecarcinautes Bott, 1960 is here synonymised with Potamonautes Macleay, 1838 . Gecarcinautes was erected by Bott (1960) to accommodate G. brincki Bott, 1960 , from South Africa, which he referred to the Gecarcinucinae in the then recognised family Potamonidae . In his revision of the Madagascan freshwater crabs, Bott (1965) assigned Thelphusa goudoti to Gecarcinautes (together with P. [P.] antongilensis and P. [P.] a. vondrozi). Although Bott (1969, 1970a, b) later included the African and Indian species of Gecarcinucinae in the Gecarcinucidae , he made no mention of the Madagascan species he had previously assigned to this subfamily. Later authors ( Ng & Takeda 1994) simply assumed that all of the Madagascan species of Gecarcinautes assigned to the Gecarcinucinae belonged there.

The Madagascan Gecarcinucinae of Bott (1965) included crabs with a bilobed terminal segment of the mandibular palp, and the photograph of the palp of G. a. antongilensis ( Bott 1965: fig. 3a, b) clearly shows a bilobed palp with a mediumsized anterior process. However, Bott (1965) failed to recognise that this type of mandibular palp is also found in Hydrothelphusa , and this confusion may have led to his erroneous assignment of H. goudoti n. comb. to Gecarcinautes . The fact that Ng & Takeda (1994) followed Bott in classifying Hydrothelphusa in the Hydrothelphusinae (Potamonautidae) and Gecarcinautes in the Gecarcinucinae ( Gecarcinucidae ) on the basis of mandibular palp characters described by Bott (1965) only compounded this confusion.

The uncertain taxonomic status of Gecarcinautes is further complicated by our examination of G. brincki , the type species of Gecarcinautes from South Africa. This taxon has a mandibular palp terminal segment with only a small ledge-like anterior process (the basal thickening of Bott 1965) which is definitely not bilobed ( Cumberlidge 1996a, b, 1999; Stewart 1997). Those authors found no justification for the family assignment of this taxon to a separate family, the Gecarcinucidae , and transferred G. brincki to Potamonautes (Potamonautidae) . The transfer of the type species of the genus Gecarcinautes (Gecarcinucinae, Gecarcinucidae ) to Potamonautes (Potamonautidae) effectively synonymising both genera, creates a few problems. This unfortunate situation raises questions about the proper generic assignment of other taxa that have been referred to Gecarcinautes , such as G. goudoti , G. a. antongilensis , G. a. vondrozi, and G. goodmani . The taxonomic status of all of these taxa is revised in the present work: G. goudoti is reassigned to Hydrothelphusa , while G. a. antongilensis , G. a. vondrozi and G. goodmani are all referred to Malagasya n. gen.

Figures

FIG. 1. — Dorsal view of the carapace of adult males of Madagascan freshwater crabs; A, Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853) n. comb.; E, Malagasya antongilensis (Rathbun, 1905) n. comb.; F, M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb., holotype (FMNH 4651). Scale bar: A, 10.5 mm; B, 14.4 mm; C, 14.1 mm; D, 12.6 mm; E, 8.9 mm; F, 6.4 mm.

FIG. 3. — Inferior view of the sternum of adult males of Madagascan freshwater crabs; A, Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853) n. comb.; E, Malagasya antongilensis (Rathbun, 1905) n. comb.; F, M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb., G, Madagapotamon humberti Bott, 1965; H, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002; I, Boreas uglowi n. gen., n. sp. Scale bar: A, 11.7 mm; B, 17.2 mm; C, 15.9 mm; D, 14.5 mm; E, 10.2 mm; F, 7 mm; G, 9.6 mm; H, 6.4 mm; I, 9.1 mm.

FIG. 4. — Left mandible of Madagascan freshwater crabs, frontal view showing the palp (J, K based on Ng & Takeda 1994); A, Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853) n. comb.; E, Malagasya antongilensis (Rathbun, 1905) n. comb.; F, M. goodmani (Cumberlidge, Boyko & Harvey, 2000) n. comb.; G, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2000; H, Boreas uglowi n. gen., n. sp.; I, Skeleosophusa gollhardi (Bott, 1965); J, S. prolixa Ng & Takeda, 1994; K, S. eumeces Ng & Takeda, 1994; L, Madagapotamon humberti Bott, 1965. Scale bar: A-I, K, L, 1.0 mm; J, 1.25 mm.

FIG. 5. — Left third maxilliped of Madagascan freshwater crabs, frontal view (J, K based on Ng & Takeda 1994); A, Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853) n. comb.; E, Malagasya antongilensis (Rathbun, 1905) n. comb.; F, M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb.; G, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002; H, Madagapotamon humberti Bott, 1965; I, Skelosophusa gollhardi (Bott, 1965); J, S. prolixa Ng & Takeda, 1994; K, S. eumeces Ng & Takeda, 1994; L, Boreas uglowi n. gen., n. sp. Scale bar: A-D, 5.0 mm; E-L, 3.5 mm.

FIG. 6. — Superior view of the carpus of the cheliped (pereiopod 1) of adult males of Madagascan freshwater crabs (J, K based on Ng & Takeda 1994); A Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853) n. comb.; E, Malagasya antongilensis (Rathbun, 1905) n. comb.; F, M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb.; G, Madagapotamon humberti Bott, 1965; H, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002; I, Skeleosophusa gollhardi (Bott, 1965); J, S. prolixa Ng & Takeda, 1994; K, S. eumeces Ng & Takeda, 1994; L, Boreas uglowi n. gen., n. sp. Scale bar: A-D, 5.5 mm; E-L, 3.5 mm.

FIG. 7. — Superior and inferior views of the merus of the cheliped (pereiopod 1) of adult males of Madagascan freshwater crabs; A, B, Hydrothelphusa agilis A. Milne-Edwards, 1872; C, D, H. madagascariensis (A. Milne-Edwards, 1872); E, F, H. bombetokensis (Rathbun, 1904); G, H, H. goudoti (H. Milne Edwards, 1853) n. comb.; I, J, Malagasya antongilensis (Rathbun, 1905) n. comb.; K, L, Madagapotamon humberti Bott, 1965; M, N, Skelosophusa gollhardi (Bott, 1965); O, P, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002; Q, R, Boreas uglowi n. gen., n. sp. Scale bar: A-H, 5.0 mm; I-T, 3.0 mm.

FIG. 8. — Last walking leg (pereiopod 5) of adult males of Madagascan freshwater crabs (H based on Ng & Takeda 1994); A, Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853) n. comb.; E, Boreas uglowi n. gen., n. sp.; F, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002; G, Madagapotamon humberti Bott, 1965; H, Skelosophusa prolixa Ng & Takeda, 1994; I, Malagasya antongilensis (Rathbun, 1905) n. comb.; J, M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb. Scale bar: A-D, 5.0 mm; E-L, 2.6 mm.

FIG. 9. — Right first gonopod (dorsal view; superior view; ventral view) and right second gonopod (dorsal view) of adult males of species of Hydrothelphusa A. Milne-Edwards, 1872; A-D, H. agilis A. Milne-Edwards, 1872; E-I, H. madagascariensis (A. Milne- Edwards, 1872); J-M, H. bombetokensis (Rathbun, 1904); N-Q, H. goudoti (H. Milne Edwards, 1853) n. comb. Scale bar: 4.5 mm.

FIG. 11. — Summaries of the known distribution of the Madagascan freshwater crabs; A, Hydrothelphusa agilis A. Milne-Edwards, 1872; B, H. madagascariensis (A. Milne-Edwards, 1872); C, H. bombetokensis (Rathbun, 1904); D, H. goudoti (H. Milne Edwards, 1853); E, Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002; F, Malagasya antongilensis (Rathbun, 1905) n. comb.; G, M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb.; H, Madagapotamon humberti Bott, 1965; I, Skelosophusa gollhardi (Bott, 1965); J, S. prolixa Ng & Takeda, 1994; K, S. eumeces Ng & Takeda, 1994; L, Boreas uglowi n. gen., n. sp.