Aradhya Pati & Bajantri & Hegde 2023, gen. nov.
Creators: name: Pati, Sameer Kumar
name: Bajantri, Parashuram Prabhu
name: Hegde, Gopalkrishna Dattatraya
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Gecarcinucidae
Aradhya

description: Aradhya gen. nov.
Type species. Aradhya placida sp. nov., by present designation; gender feminine.
Diagnosis. Carapace transversely ovate, broader than long (CW/CL = 1.2–1.3), strongly inflated, deep (CH / CW = 0.6–0.7); dorsal surface generally smooth, glabrous, strongly arched; anterolateral margins cristate, lacking distinct serrations; front strongly deflexed, with narrow anterior margin (FW/CW = 0.25); frontal medial triangle incomplete, lateral margins indiscernible; epigastric and postorbital cristae poorly developed; external orbital angle indistinct; epibranchial tooth very low; branchial regions strongly inflated; cervical grooves relatively shallow, not reaching level of postorbital cristae; epistome posterior margin with distinct, triangular medial lobe and strongly sinuous lateral lobes (Figs. 2A, B, 3A, C, E, 4A–C). First, second maxillipeds each with long flagellum on exopod (Fig. 5A). TME lacking flagellum or with relatively short flagellum, reaching about half width of merus (Figs. 3G, 4D, 5B). Chelipeds relatively smooth, unequal in adult males (Figs. 2A, C, 3A–F) and subequal in adult females (Fig. 4A, C). Ambulatory legs slender, long; dactylus (P2–P5) recurved, longer than propodus, distal chitinous part very short or reduced (Figs. 2A, C, 3A–F, 4A–C). Male s2/s3 cristate, not reaching edge of sternum; male s3/s4 deep, broad, reaching edge of sternum (Figs. 2C, 3B, D, F, 5C). Male pleonal locking mechanism with low tubercles on submedial part of s5 (Fig. 5C). Male sternopleonal cavity relatively short, reaching anteriorly to level of mid-length of cheliped coxae (Figs. 2C, 3B, D, F, 5C). Male pleon relatively narrow, triangular; pleonal somite 6 trapezoidal, relatively narrow (proximal width ca. 1.3× medial length), shorter than telson, with gently concave lateral margins (Figs. 2C, 3B, D, F, 5D, 6A). Male telson narrow, elongated (medial length ca. 1.3–1.4× proximal width), with gently concave lateral margins (Figs. 2C, 3B, D, F, 5D, 6A). G1 relatively stout, long, tip reaching pleonal locking structure in situ; flexible zone small; ultimate article relatively stout, conical, relatively short, ca. 0.3× length of penultimate article, gently curved outwards at angle of ca. 15° from longitudinal axis, tip broad, tubular, dorsal flap absent; penultimate article relatively stout, outer margin strongly convex, shelf-like at basal half, inner margin characteristically convex distally (Figs. 3H, 5E, 6B–E). G2 distinctly shorter than G1, ca. 0.6× length of G1; ultimate article very short, ca. 0.2× length of penultimate article (Figs. 3I, 5F, 6F). Female pleon and telson ovate in outline; pleonal somite 6 subequal in length to telson; telson subtriangular, with broad, straight apex (Fig. 4E). Female pleopods 2–5 endopods slender and longer than exopods; pleopods 3–5 exopods conspicuously stouter than endopods (Fig. 4F). Vulvae on s6 close to each other (VD/SW = ca. 0.1), opening inwards, subovate, large, touching s5/s6 (Fig. 4G).
Etymology. The genus is named after Miss Aaradhya Bajantri, the only daughter of the second author of the present paper. “ Aradhya ” also means “the first one” in Sanskrit. Crabs of this new genus are the first ones among the Indian gecarcinucid crabs observed to be non-aggressive and quite calm. Gender: feminine.
Remarks. Among the Indian gecarcinucid genera, Aradhya gen. nov. most closely resembles Arcithelphusa, Cylindrotelphusa, Rajathelphusa, and Pavizham, because all possess an ovate, relatively narrow (CW/CL = 1.2– 1.4) and deep carapace (CH /CW = 0.5–0.7), with a narrow front (FW/CW = 0.25) and an incomplete frontal median triangle (Figs. 2A, B, 3A, C, E, 4A–C; see Pati et al. 2019: fig. 2A, B, D, E; Bahir & Yeo 2007: fig. 5A, B; Pati et al. 2017: figs. 11a, b, 13a, b; Raj et al. 2021: figs. 3A, B, 7A, C; Raj et al. 2022: figs. 3A, C, 8A, C). Aradhya gen. nov. is nevertheless distinguished from Arcithelphusa, Cylindrotelphusa, Rajathelphusa, and Pavizham mainly by its narrow and elongated male telson, the medial length ca. 1.3–1.4 times the proximal width (Figs. 2C, 3B, D, F, 5D, 6A) (vs. male telson relatively broader and shorter, the medial length ca. 0.9–1.1 times the proximal width; see Pati et al. 2019: fig. 2C, F; Bahir & Yeo 2007: fig. 5C; Pati et al. 2017: figs. 11h, 13h; Raj et al. 2021: figs. 3D, 7E; Raj et al. 2022: figs. 4A, 9C), the relatively stouter ultimate article of the G1 (Figs. 3H, 5E, 6B–E) (vs. G1 ultimate article relatively slender; see Pati et al. 2019: fig. 3E, F, J, O; Bahir & Yeo 2007: fig. 4A–C; Pati et al. 2017: figs. 12a–c, 14a–c; Raj et al. 2021: fig. 9B–D, F–H; Raj et al. 2022: figs. 5C–E, 10A–C), and the characteristically convex distal inner margin of the penultimate article of the G1 (Figs. 3H, 5E, 6B, C) (vs. G1 penultimate article with an almost straight distal inner margin; see Pati et al. 2019: fig. 3E, F, J, O; Bahir & Yeo 2007: fig. 4A, C; Pati et al. 2017: figs. 12a, b, 13a, b; Raj et al. 2021: fig. 9B, D, F, H; Raj et al. 2022: figs. 5C, E, 10A, C).
Aradhya gen. nov. is morphologically closer to Arcithelphusa than any other Indian genera of gecarcinucid crabs as both genera share several features in common, including a strongly arched and generally smooth dorsal surface of the carapace (Figs. 2A, B, 3A, C, E, 4A–C; see Pati et al. 2019: fig. 2A, B, D, E), the absence of distinct serrations on the anterolateral margins of the carapace (Figs. 2A, 3A, C, E, 4A–C; see Pati et al. 2019: fig. 2A, D), the poorly developed epigastric and postorbital cristae (Figs. 2A, 3A, C, E, 4A–C; see Pati et al. 2019: fig. 2A, D), an indistinct external orbital angle (Figs. 2A, 3A, C, E, 4A–C; see Pati et al. 2019: fig. 2A, D), the relatively shallow and short cervical grooves (Figs. 2A, 3A, C, E, 4A–C; see Pati et al. 2019: fig. 2A, D), the absence of a flagellum or with a relatively short flagellum on the TME (Figs. 3G, 4D, 5B; see Pati et al. 2019: fig. 3B, N), the relatively smooth chelipeds (Figs. 2A, C, 3A–F, 4A–C; see Pati et al. 2019: fig. 2A–F), the relatively shorter male sternopleonal cavity reaching anteriorly to the level of mid-length of the cheliped coxae (Figs. 2C, 3B, D, F, 5C; see Pati et al. 2019: fig. 2C, F), the relatively stout G1 with a relatively shorter ultimate article, ca. 0.3–0.4 times the length of the penultimate article and the strongly convex outer margin of the penultimate article at the basal half (Figs. 3H, 5E, 6B–E; see Pati et al. 2019: fig. 3E, F, J, O), and the relatively shorter G2, ca. 0.6–0.7 times the length of the G1, with a very short ultimate article, ca. 0.2 times the length of the penultimate article (Figs. 3I, 5F, 6F; see Pati et al. 2019: fig. 3H, K, P). In addition to the shorter, elongated male telson and the stouter G1 ultimate article of the new genus, Aradhya gen. nov. is differentiated from Arcithelphusa by the relatively narrow male pleon (Figs. 2C, 3B, D, F, 5D, 6A) (vs. male pleon relatively broad; see Pati et al. 2019: figs. 2C, F, 3D), the relatively narrow male pleonal somite 6, the proximal width ca. 1.3 times the medial length (Figs. 2C, 3B, D, F, 5D, 6A) (vs. male pleonal somite 6 relatively broad, the proximal width ca. 1.7–1.8 times the medial length; see Pati et al. 2019: figs. 2C, F, 3D), the relatively small flexible zone of the G1 (Figs. 3H, 5E, 6B, C) (vs. G1 flexible zone relatively large; see Pati et al. 2019: fig. 3E, J, O), and the gently curved ultimate article of the G1 (Figs. 3H, 5E, 6B, D) (vs. G1 ultimate article strongly bent; see Pati et al. 2019: fig. 3E, F, J, O). Aradhya gen. nov. is found at a lower elevation (629 m) on an isolated mountain, which is surrounded by the Kali and Gangavali rivers, with deep valleys (Fig. 1). The known congeners of Arcithelphusa have been recorded from the Wayanad mountain plateau at slightly higher elevations (709–864 m) (Fig. 1). The Wayanad plateau is some 350 km away from the Bare where Aradhya gen. nov. occurs. The Western Ghats between the Wayanad plateau and the Bare has some mountain peaks and deep valleys (Fig. 1), which form “sky islands” acting as barriers between these two genera. The morphological differences and the geographical isolation between them corroborate the recognition of Aradhya gen. nov.
Aradhya gen. nov. is further separated from Cylindrotelphusa and Rajathelphusa by the generally smooth dorsal surface of the carapace (Figs. 2A, 3A, C, E, 4A–C) (vs. carapace dorsal surface relatively rugose; see Bahir & Yeo 2007: fig. 5A; Pati et al. 2017: figs. 11a, 13a; Raj et al. 2021: figs. 3A, 7A; Raj et al. 2022: fig. 8A); the relatively shallow cervical grooves (Figs. 2A, 3A, C, E, 4A–C) (vs. cervical grooves relatively deep; see Bahir & Yeo 2007: fig. 5A; Pati et al. 2017: figs. 11a, 13a; Raj et al. 2021: figs. 3A, 7A; Raj et al. 2022: fig. 8A); the lack of a flagellum or at most with a shorter flagellum on the TME, which is about half the width of the merus (Figs. 3G, 4D, 5B) (vs. flagellum on the TME relatively long, reaching beyond half the width of the merus; see Pati et al. 2017: figs. 11i, 13i; Raj et al. 2021: figs. 3C, 7D; Raj et al. 2022: fig. 9A); the relatively smooth chelipeds (Figs. 2A, C, 3A–F, 4A–C) (vs. chelipeds relatively rugose; see Bahir & Yeo 2007: fig. 5A–C; Pati et al. 2017: figs. 11a, c, d, 13a, c, d; Raj et al. 2021: figs. 3A, 4G, 7A, G; Raj et al. 2022: figs. 8A, 9D); the gently concave lateral margins of the male telson (Figs. 2C, 3B, D, F, 5D, 6A) (vs. male telson with strongly concave lateral margins; see Bahir & Yeo 2007: fig. 5C; Pati et al. 2017: figs. 11h, 13h; Raj et al. 2021: figs. 3D, 7E; Raj et al. 2022: fig. 9C); the relatively stout G1 (Figs. 3H, 5E, 6B, D) (vs. G1 relatively slender; see Bahir & Yeo 2007: fig. 4A, B; Pati et al. 2017: figs. 12a, c, 14a, c; Raj et al. 2021: figs. 9B, F; Raj et al. 2022: fig. 10A); and the relatively stouter penultimate article of the G1, with the outer margin being strongly convex and shelf-like at the basal half (Figs. 3H, 5E, 6B, D) (vs. G1 penultimate article relatively slenderer, with the outer margin straight to relatively less convex at the basal half; see Bahir & Yeo 2007: fig. 4A, B; Pati et al. 2017: figs. 12a, c, 14a, c; Raj et al. 2021: figs. 9B, F; Raj et al. 2022: fig. 10A). The anterolateral margins of the carapace lack distinct serrations (Figs. 2A, 3A, C, E, 4A–C), and the G1 ultimate article is relatively shorter, ca. 0.3 times the length of the penultimate article (Figs. 3H, 5E, 6B) in Aradhya gen. nov.; whereas the anterolateral margins have distinct serrations (see Bahir & Yeo 2007: fig. 5A; Pati et al. 2017: figs. 11a, 13a), and the G1 ultimate article is relatively longer, ca. 0.4–0.6 times the length of the penultimate article (see Bahir & Yeo 2007: fig. 4A; Pati et al. 2017: figs. 12a, 14a) in Cylindrotelphusa. The epigastric and postorbital cristae are poorly developed (Figs. 2A, 3A, C, E, 4A–C), the external orbital angle is indistinct (Figs. 2A, 3A, C, E, 4A–C), and the G2 is relatively shorter, ca. 0.6 times the length of G1, with the ultimate article very short, ca. 0.2 times the length of the penultimate article (Figs. 3I, 5F, 6F) in Aradhya gen. nov.; whereas the epigastric and postorbital cristae are well-developed (see Raj et al. 2021: figs. 3A, 4A, B, 7A, B; Raj et al. 2022: fig. 8A, B), the external orbital angle is distinct (see Raj et al. 2021: figs. 3A, 4A, B, 7A, B; Raj et al. 2022: fig. 8A, B), and the G2 is relatively longer, ca. 1.0 times the length of G1, with the ultimate article long, ca. 0.5 times the length of the penultimate article (see Raj et al. 2021: fig. 9E, I; Raj et al. 2022: fig. 10D) in Rajathelphusa. Cylindrotelphusa is known to dwell in both lower and higher elevations (3–980 m), but it is restricted to the southern Indian states of Kerala and Tamil Nadu (Fig. 1). Cylindrotelphusa is probably not known beyond these two states, and this fact along with the morphological differences between Cylindrotelphusa and Aradhya gen. nov. support their generic separation. On the other hand, Rajathelphusa occurs at high mountains (750–1623 m altitude) of the Southern Western Ghats and is geographically clearly isolated from Aradhya gen. nov. of the Central Western Ghats mainly by the Palghat gap (Fig. 1).
The superficial resemblance of Aradhya gen. nov. with Pavizham notwithstanding, the new genus is distinct from the latter genus mainly by the elongated male telson and the stouter G1 ultimate article. Other important differences between them are as follows: the carapace is deeper and strongly arched dorsally, CH /CW = 0.6–0.7 (Figs. 2A, B, 3A, C, E, 4A–C) in Aradhya gen. nov. (vs. carapace less deep and gently arched dorsally, CH /CW = 0.5 in Pavizham; see Raj et al. 2022: fig. 3A, C); the flagellum on the TME is missing or with a shorter flagellum, which reaches about half the width of the merus (Figs. 3G, 4D, 5B) in Aradhya gen. nov. (vs. flagellum on the TME almost as long as the width of the merus in Pavizham; see Raj et al. 2022: fig. 5A); the chelipeds are relatively smooth (Figs. 2A, C, 3A–F, 4A–C) in Aradhya gen. nov. (vs. chelipeds relatively rugose in Pavizham; see Raj et al. 2022: figs. 3A, 4D); the male s2/s3 does not reach the edges of the sternum (Figs. 2C, 3B, D, F, 5C) in Aradhya gen. nov. (vs. male s2/s3 reaching the edges of the sternum in Pavizham; see Raj et al. 2022: figs. 3D, 4B, 5B); the male sternopleonal cavity is relatively shorter, reaching anteriorly to the level of mid-length of the cheliped coxae (Figs. 2C, 3B, D, F, 5C) in Aradhya gen. nov. (vs. male sternopleonal cavity relatively longer, reaching anteriorly to the level of the anterior margin of the cheliped coxae in Pavizham; see Raj et al. 2022: figs. 3D, 4B); the male pleon is relatively narrow, with the pleonal somite 6 being relatively narrow, the proximal width ca. 1.3 times the medial length (Figs. 2C, 3B, D, F, 5D, 6A) in Aradhya gen. nov. (vs. male pleon relatively broad, with relatively broad pleonal somite 6, the proximal width ca. 1.7 times the medial length in Pavizham; see Raj et al. 2022: figs. 3D, 4A); the outer margin of the G1 penultimate article is strongly convex and shelf-like at the basal half (Figs. 3H, 5E, 6B, C) in Aradhya gen. nov. (vs. G1 penultimate article with a less convex outer margin at the basal half in Pavizham; see Raj et al. 2022: fig. 5C–E); and the G2 is short, ca. 0.6 times the length of G1, with the ultimate article very short, ca. 0.2 times the length of the penultimate article (Figs. 3I, 5F, 6F) in Aradhya gen. nov. (vs. G2 long, ca. 1.4 times the length of G1, with the ultimate article long, ca. 0.6 times the length of the penultimate article in Pavizham; see Raj et al. 2022: fig. 5F). Aradhya gen. nov. is also separated from Pavizham geographically as both genera are apart from each other by a distance of about 650 km with several mountain peaks and deep valleys, including the prominent Palghat gap between the Central- and Southern Western Ghats (Fig. 1).
Crabs of the following genera are likely to coexist with Aradhya gen. nov.: Barusa Pati & Yeo, 2022; Barytelphusa Alcock, 1909; Ghatiana Pati & Sharma, 2014; Vanni Bahir & Yeo, 2007; and Vela Bahir & Yeo, 2007 (cf. Pati & Thackeray 2021; Pati & Yeo 2022; Pati et al. 2022a, 2023; unpublished data). Aradhya gen. nov. need not be confused with those genera because its carapace is relatively deep, with the front relatively narrow (Fig. 2B) (vs. carapace relatively low, with the front relatively wider; see Bahir & Yeo 2007: fig. 32B; Pati & Thackeray 2021: fig. 4C; Pati & Yeo 2022: figs. 1B, 10B; Pati et al. 2022a: fig. 3B; Pati et al. 2023: fig. 2B). In Aradhya gen. nov., the epigastric and postorbital cristae are poorly developed (Fig. 2A) (vs. epigastric and postorbital cristae well developed in Barusa and Barytelphusa; see Pati & Yeo 2022: figs. 1A, 10A), the external orbital angle is indistinct (Fig. 2A) (vs. external orbital angle distinct in Barusa and Barytelphusa; see Pati & Yeo 2022: figs. 1A, 10A), the flagellum on the TME is absent or relatively short (Figs. 3G, 4D, 5B) (vs. flagellum on the TME relatively long in Barusa and Barytelphusa; see Pati & Yeo 2022: fig. 1D), the male s3/s4 is distinct (Fig. 5C) (vs. male s3/s4 indiscernible in Barusa and Barytelphusa; see Pati & Yeo 2022: figs. 1F, 10C), and the G1 ultimate article is relatively stout and short, ca. 0.3 times the length of the penultimate article (Fig. 6B) (vs. G1 ultimate article relatively slender and long, ca. 0.6–0.8 times the length of the penultimate article in Barusa and Barytelphusa; see Pati & Yeo 2022: figs. 3A, 7I). The G2 is shorter than the G1, with the ultimate article very short, ca. 0.2 times the length of the penultimate article in Aradhya gen. nov. (Fig. 6B, F); whereas the G2 is as long as or longer than the G1, with the ultimate article relatively long, ca. 0.3–0.5 times the length of the penultimate article in Vanni and Vela (see Bahir & Yeo 2007: fig. 31C, G; Pati et al. 2023: fig. 4E, I). Aradhya gen. nov. is further separated from Ghatiana by the distinct male s2/s3 and s3/s4 (Fig. 5C) (vs. male s2/s3 and s3/s4 indistinct in Ghatiana; see Pati & Thackeray 2021: fig. 5C; Pati et al. 2022a: fig. 3C); the relatively short male sternopleonal cavity, which reaches anteriorly to the level of mid-length of the cheliped coxae (Fig. 5C) (vs. male sternopleonal cavity relatively long, reaching anteriorly beyond the level of the bases of the third maxillipeds in Ghatiana; see Pati & Thackeray 2021: fig. 5C; Pati et al. 2022a: fig. 3C); and the relatively stouter ultimate article of the G1 (Fig. 6B) (vs. G1 ultimate article relatively slender in Ghatiana; see Pati & Thackeray 2021: fig. 5D; Pati et al. 2022a: fig. 4D).
Geographic distribution. Aradhya gen. nov. is currently known only from an isolated mountain of the Central Western Ghats in the Uttara Kannada district of Karnataka state, India (Fig. 1).
description: Published as part of Pati, Sameer Kumar, Bajantri, Parashuram Prabhu & Hegde, Gopalkrishna Dattatraya, 2023, A new genus and new species of freshwater crab (Decapoda: Brachyura: Gecarcinucidae) from the Central Western Ghats of India, pp. 161-175 in Zootaxa 5285 (1) on pages 163-170, DOI: 10.11646/zootaxa.5285.1.7, http://zenodo.org/record/7935889