Vahatra, Leever & Daniels & Soma & Cumberlidge, 2022

Leever, Ellen M., Daniels, Savel R., Soma, Julia B. & Cumberlidge, Neil, 2022, Two new genera and a new species of freshwater crabs from northern Madagascar: Vahatra gen. nov. for Foza ambohitra Cumberlidge and Meyer, 2009, and Toamasina gen. nov. for Toamasina clarki sp. nov. (Brachyura: Potamoidea: Deckeniidae), Journal of Natural History 56 (1 - 4), pp. 241-263 : 245-248

publication ID	https://doi.org/ 10.1080/00222933.2022.2049389
DOI	https://doi.org/10.5281/zenodo.6762503
persistent identifier	https://treatment.plazi.org/id/9529DB19-FFED-FFAA-3950-FE07FECB8F60
treatment provided by	Plazi
scientific name	Vahatra
status	gen. nov.

Treatment

Vahatra gen. nov.

( Figures 1 View Figure 1 (a,c,e), 2(a,c,e), 3(a), 4(a,b,e,f), 5(a,b,c), 6; Tables 1–4 View Table 1 View Table 2 View Table 3 )

Nomenclatural statement: A life science identifier (LSID) number was obtained for the new genus:

Foza – Cumberlidge and Meyer View Cited Treatment 2009: 79–84, figs 1–3, tab. 1.

Type species

Foza ambohitra Cumberlidge and Meyer, 2009 , by present designation.

Diagnosis

Entire carapace surface smooth; anterolateral margin smooth; epibranchial tooth small, acute, close to exorbital tooth, positioned in line with postorbital margin ( Figure 1 View Figure 1 (a)); shallow notch between exorbital, epibranchial teeth; lateral carapace margin smooth; suborbital, subhepatic regions of branchiostegite smooth, pterygostomial region smooth except for small field of granules at junction of longitudinal, vertical sutures; large anterior lobe on terminal article of mandibular palp; ambulatory legs (P2–5) stout, not elongated; cheliped ischium margin smooth, rounded; S4/5 thoracic sternal sulcus meeting pleon at PL5/6 suture; PL6 relatively narrow with convex lateral margins; telson lateral margins gently sinuous, apex rounded; third maxilliped exopod with short flagellum (~ 0.5× merus length). G1 TA dorsal side glabrous, broadest proximally, distal half curving upward, tip broad ( Figure 5 View Figure 5 (a,b)); G2 TA long (G2 TA/SA = 0.6), flagellum-like, with distinct distal curve ( Figure 5 View Figure 5 (c)).

Distribution

Endemic to Madagascar. Vahatra gen. nov. is known from three locations in the Diana Region of Antsiranana Province in northern Madagascar: Ambohitra, the Analamerana Special Reserve and the Ankarana Special Reserve ( Figure 6 View Figure 6 ).

Type species

Foza ambohitra Cumberlidge and Meyer, 2009 , by present designation.

Etymology

The genus name recognises the contributions of the Vahatra Association of Madagascar, whose objective is to train Malagasy field scientists in conservation biology in order to protect the unique biotic resources of that island nation. Most of the specimens of Vahatra ambohitra ( Cumberlidge and Meyer, 2009) comb. nov. in the present work were collected by Dr Steve M. Goodman, a founding member of the Vahatra Association. The generic name, Vahatra , is used as a Latin noun in nominative singular and treated as feminine.

Species included

Vahatra ambohitra ( Cumberlidge and Meyer, 2009) comb. nov.

Remarks

The classification used here for the Afrotropical freshwater crab fauna follows that proposed recently by Cumberlidge and Daniels (2022), who recognised two families in the region: the Potamonautidae Bott, 1970 (endemic to continental Africa) and the Deckeniidae Ortmann, 1897 (found in West and East Africa, The Seychelles and Madagascar). Those authors included the entire Malagasy freshwater crab fauna in the deckeniid subfamily Hydrothelphusinae Bott, 1955 .

The new genus is established based on morphological and phylogenetic evidence. The molecular phylogeny in Cumberlidge et al. (2020, fig. 1) indicates that V. ambohitra ( Cumberlidge and Meyer, 2009) comb. nov. is part of a unique clade that is genetically separated from F. raimundi (the type species of Foza ) and from all other Malagasy genera.

Vahatra gen. nov. is part of a morphological group with seven other Malagasy genera ( Agora , Crosnautes Cumberlidge, Soma, Leever, Clark and Daniels, 2021 , Foza , Glabrithelphusa Meyer, Cumberlidge and Koppin, 2014 , Hydrothelphusa A. MilneEdwards, 1872 , Marojejy Cumberlidge, Boyko, and Harvey, 2002 , Malagasya Cumberlidge and Sternberg, 2002 , and Toamasina gen. nov.) that all have a mandibular palp with a clearly bilobed terminal article, whose anterior lobe is conspicuous and medium-sized (MPAL/MPTA = 0.4–0.6) (see Cumberlidge and Sternberg 2002, fig. 4a–g). On the other hand, the size of the anterior lobe on the terminal article of the mandibular palp of Vahatra gen. nov. (MPAL/MPTA = 0.4) ( Figure 2 View Figure 2 (a,c); Table 2 View Table 2 ) distinguishes it from Boreathelphusa (Cumberlidge, 2010) , Madagapotamon Bott, 1955 and Skelosophusa Ng and Takeda, 1994 , whose mandibular palp has a small but distinct ledge-like anterior lobe (MPAL/MPTA = 0.2) (see Cumberlidge and Sternberg 2002, fig. 4h–l).

Vahatra gen. nov. can be distinguished from Agora by the incomplete and faint postfrontal crest that does not traverse the entire carapace ( Figure 1a View Figure 1 ), vs a welldefined postfrontal crest that completely traverses the carapace (see Cumberlidge et al. 2020). Vahatra gen. nov. can be distinguished from Crosnautes and Foza by the smooth anterolateral corners of the carapace surface ( Figure 1 View Figure 1 (a)), vs anterolateral corners of the carapace with fields of well-defined carinae in Crosnautes (see Cumberlidge et al. 2021, fig. 1a,b) and Foza ( Figure 7 View Figure 7 (a,c)). Vahatra gen. nov. can be distinguished from Glabrithelphusa by the G1 TA which is broad basally, tapers evenly and curves upward distally in Vahatra gen. nov. ( Figure 5 View Figure 5 (a,b)), vs a G1 TA that is broadest at the mid-point and is straight along its length ( Meyer et al. 2014, figs 1a, 3a). The new genus can be distinguished from Hydrothelphusa by the shallow notch between the exorbital and epibranchial teeth in Vahatra gen. nov. ( Figure 1 View Figure 1 (a)), vs a deep cleft between these teeth (see Cumberlidge and Sternberg 2002, fig. 1a–c; Cumberlidge et al. 2007, figs 1, 16). Vahatra gen. nov. can be distinguished from Malagasya by the smooth anterolateral margin of the carapace ( Figure 1a View Figure 1 ), vs small or conspicuous teeth lining this margin (see Cumberlidge and Sternberg 2002, fig. 1e,f; Cumberlidge et al. 2020, fig. 10a,c,e). Vahatra gen. nov. can be distinguished from Marojejy by its short ambulatory legs (ΣP2–5/CW = 5.7) ( Figure 3 View Figure 3 (a); Table 3 View Table 3 ) and normal-length eyestalks and corneas ( Figure 1 View Figure 1 (a)), vs long, slender, and elongated ambulatory legs (ΣP2–5/CW = 7.0) and eyestalks that taper distally and have a reduced cornea (see Cumberlidge et al. 2002, fig. 2f).

Finally, Vahatra gen. nov. can be distinguished from Toamasina gen. nov. as follows. The margin of the cheliped ischium of Vahatra gen. nov. is smooth and rounded ( Figure 4 View Figure 4 (e,f)), vs a cheliped ischium margin lined with small teeth ( Figure 4 View Figure 4 (g,h)); the S4/5 thoracic sternal sulcus of Vahatra gen. nov. meets the pleon at the PL5/6 suture ( Figure 1 View Figure 1 (e)), vs an S4/5 sulcus that meets the pleon at the PL/6 suture ( Figure 1 View Figure 1 (f)); the PL6 is relatively narrow with convex lateral margins in Vahatra gen. nov. ( Figure 1 View Figure 1 (e)), vs a relatively broad PL6 with gently concave lateral margins ( Figure 1 View Figure 1 (f)); the telson has gently sinuous lateral margins with a rounded apex in Vahatra gen. nov. ( Figure 1 View Figure 1 (e)), vs a telson with straight lateral margins with a rounded apex ( Figure 1 View Figure 1 (f)); the exopod of the third maxilliped has a short flagellum (less than the merus length) in Vahatra gen. nov. ( Figure 2 View Figure 2 (e)), vs a third maxilliped exopod with a long flagellum (equal to the merus length) ( Figure 2 View Figure 2 (f)); the ambulatory legs (P2–5) are short (ΣP2–5/CW = 5.7) in Vahatra gen. nov. ( Table 3 View Table 3 ), vs ambulatory legs (P2–5) that are of medium length (ΣP2–5/CW = 6.4) in Tomasina gen. nov. ( Table 3 View Table 3 ); the G1 TA is broadest proximally with a distal half that curves upward and ends in a broad tip in Vahatra gen. nov. ( Figure 5 View Figure 5 (a,b)), vs a G1 TA that is widest at the midpoint, with a distal half that is straight and ends in a pointed tip ( Figure 5 View Figure 5 (d,e)); and a G2 TA that is long and flagellum-like and ends in a distinct distal curve in Vahatra gen. nov. ( Figure 5 View Figure 5 (c)), vs a G2 TA that is long and flagellum-like but is straight and not curved distally ( Figure 5 View Figure 5 (f)).