Vahatra Leever & Daniels & Soma & Cumberlidge 2022, gen. nov.
Creators: name: Leever, Ellen M.
name: Daniels, Savel R.
name: Soma, Julia B.
name: Cumberlidge, Neil
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Potamonautidae
Vahatra

description: Vahatra gen. nov.
(Figures 1 (a,c,e), 2(a,c,e), 3(a), 4(a,b,e,f), 5(a,b,c), 6; Tables 1–4)
Nomenclatural statement: A life science identifier (LSID) number was obtained for the new genus:
Foza – Cumberlidge and Meyer 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 (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 (a,b)); G2 TA long (G2 TA/SA = 0.6), flagellum-like, with distinct distal curve (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).
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 (a,c); 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), 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 (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 (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 (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 (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), 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 (a); Table 3) and normal-length eyestalks and corneas (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 (e,f)), vs a cheliped ischium margin lined with small teeth (Figure 4 (g,h)); the S4/5 thoracic sternal sulcus of Vahatra gen. nov. meets the pleon at the PL5/6 suture (Figure 1 (e)), vs an S4/5 sulcus that meets the pleon at the PL/6 suture (Figure 1 (f)); the PL6 is relatively narrow with convex lateral margins in Vahatra gen. nov. (Figure 1 (e)), vs a relatively broad PL6 with gently concave lateral margins (Figure 1 (f)); the telson has gently sinuous lateral margins with a rounded apex in Vahatra gen. nov. (Figure 1 (e)), vs a telson with straight lateral margins with a rounded apex (Figure 1 (f)); the exopod of the third maxilliped has a short flagellum (less than the merus length) in Vahatra gen. nov. (Figure 2 (e)), vs a third maxilliped exopod with a long flagellum (equal to the merus length) (Figure 2 (f)); the ambulatory legs (P2–5) are short (ΣP2–5/CW = 5.7) in Vahatra gen. nov. (Table 3), vs ambulatory legs (P2–5) that are of medium length (ΣP2–5/CW = 6.4) in Tomasina gen. nov. (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 (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 (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 (c)), vs a G2 TA that is long and flagellum-like but is straight and not curved distally (Figure 5 (f)).
description: Published as part of 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), pp. 241-263 in Journal of Natural History 56 (1 - 4) on pages 245-248, DOI: 10.1080/00222933.2022.2049389, http://zenodo.org/record/6758291