Patithelphusa, Mitra & Rath & Jung & Kim & Kundu, 2025

Patithelphusa gen. nov.

Type species.

Patithelphusa yercaudensis sp. nov., by present designation.

Diagnosis.

Carapace distinctly broader than long, dorsal surface distinctly convex, lateral margins with many short oblique striae (Fig. 2 A View Figure 2 ); dorsal surface distinctly convex in frontal view (Fig. 2 B View Figure 2 ); external orbital angle widely triangular, blunt, outer margin serrated, 4.5 times of inner margin (Fig. 2 A View Figure 2 ); epibranchial tooth short, distinct notch between epibranchial tooth and outer margin of external orbital tooth; cervical groove well demarcated in all course, broad and shallow anteriorly, relatively deep and narrow posteriorly, not reaching to the postorbital cristae; epistomal median lobe with distinct triangular tooth, tip bilobed; third maxilliped exopods with long flagellum (Fig. 2 D View Figure 2 ); suture between S 2 / S 3 shallow and broad, not reaching to lateral margins of sternum; suture between S 3 / S 4 shallow and broad, not interrupted by any ridge, reaching to lateral edge of sternum. Sixth pleonal segment of male slightly broader than long (Fig. 2 C, E, F View Figure 2 ); G 1 subterminal segment relatively slender, basally broad; terminal segment cone shaped, elongated, 0.4 times of subterminal segment, inner margin straight, outer margin convex in middle, with some long setae, tip triangular, not sharp. G 2 c. 1.2 times longer than G 1, subterminal segment long, basally broad, terminal segment slightly shorter than half of subterminal segment (Fig. 3 A – C View Figure 3 ).

Etymology.

The genus is named after eminent crustacean taxonomist, Dr Sameer Kumar Pati, for his valuable contribution to freshwater crab taxonomy in India. The gender is neuter.

Remarks.

The new genus Patithelphusa shares similarities with only four gecarcinucid genera, Baratha , Travancoriana , Vanni and Vela , by having a combination of characters: exopods of third maxilliped with long flagellum, and the distal segment of G 2 is relatively long. Patithelphusa gen. nov. can nevertheless be separated from Baratha by its anterolateral and posterolateral region of carapace dorsal surface with many horizontal and oblique striae (Fig. 2 A View Figure 2 ) (vs. anterolateral and posterolateral region of carapace dorsal surface smooth in Baratha ; figs 19 a, 21 a, Bahir and Yeo 2007); external orbital angle widely triangular, blunt (Fig. 2 A View Figure 2 ) (vs. external orbital angle sharp, produced; figs 19 a, 21 a, Bahir and Yeo 2007); pleonal somite six of male distinctly broader than long (Fig. 2 C, E View Figure 2 ) (vs. pleonal somite six of male squarish to slight longer than broad; figs 18 b, 19 c, 21 c, Bahir and Yeo 2007); antennular fossae rectangular (Fig. 2 B View Figure 2 ) (vs. eye shaped, medially broad, gradually narrower in both ends, figs 19 b, 21 b, Bahir and Yeo 2007); G 1 terminal segment relatively longer, tip blunt (Fig. 3 A, B View Figure 3 ) (vs. G 1 terminal segment relatively shorter, cone shaped, tip pointed; figs 18 c – g, 20 a – e, Bahir and Yeo 2007).

Patithelphusa gen. nov. can be separated from Travancoriana by several morphological characters: the dorsal surface of carapace distinctly convex in frontal and as well as in dorsal view in Patithelphusa gen. nov. (Fig. 2 A, B View Figure 2 ) (vs. carapace dorsal surface slightly convex in frontal view in Travancoriana ; taf. 4, figs 38, 39, Bott 1970; fig. 8 a, b, Bahir and Yeo 2007); somite six of male pleon distinctly broader than long (Fig. 2 C, E View Figure 2 ) (vs. somite six of male pleon longer than broad; taf. 4, fig. 40, Bott 1970; figs 7 d, 8 c, Bahir and Yeo 2007); outer margin of external orbital tooth serrated (Fig. 2 A View Figure 2 ) (vs. outer margin of external orbital tooth smooth; taf. 4, fig. 39, Bott 1970; fig. 8 a, Bahir and Yeo 2007); epigastric cristae separated from postorbital cristae by a small gap (Fig. 2 A View Figure 2 ) (vs. epigastric cristae confluent with postorbital cristae; taf. 4, fig. 39, Bott 1970; fig. 8 a, Bahir and Yeo 2007); epibranchial tooth small but discernible, cleft distinct (Fig. 2 A View Figure 2 ) (vs. epibranchial tooth indistinct, cleft not visible; taf. 4, fig. 39, Bott 1970; fig. 8 a, Bahir and Yeo 2007). Outer orbital margin of epibranchial tooth is distinctly straight in Patithelphusa (Fig. 2 A View Figure 2 ) (vs. outer orbital margin of epibranchial tooth distinctly convex in Travancoriana ; taf. 4, fig. 39, Bott 1970; fig. 8 a, Bahir and Yeo 2007); G 1 terminal segment cone shaped, elongated, 0.4 times of subterminal segment, tip triangular, not sharp (Fig. 3 A, B View Figure 3 ) (vs. G 1 terminal segment relatively longer c. 0.3-0.6 times of subterminal segment, tip acute; figs 7 f – h, 16 f-I, Bahir and Yeo 2007).

The genus Vanni superficially resembles Patithelphusa gen. nov., but the latter exhibits several distinguishing characteristics: carapace almost squarish in Vanni (fig. 32 a, Bahir and Yeo 2007), while distinctly wider than long in Patithelphusa gen. nov. (Fig. 2 A View Figure 2 ); carapace flat or slightly convex in frontal view (fig. 32 b, Bahir and Yeo 2007), however the carapace of the new genus is convex in frontal and dorsal view (Fig. 2 A, B View Figure 2 ); suture between S 2 / S 3 indistinct or slightly visible in Vanni (fig. 32 b, Bahir and Yeo 2007), while S 2 / S 3 is distinctly visible in Patithelphusa gen. nov (Fig. 2 C, F View Figure 2 ); suture between sternites S 3 / S 4 indistinct (fig. 32 b, Bahir and Yeo 2007) vs. S 3 / S 4 distinct and reaches the lateral margins of the sternum in Patithelphusa gen. nov (Fig. 2 C, F View Figure 2 ); G 1 terminal segment cone shaped, elongated, 0.4 times of subterminal segment, inner margin straight, outer margin convex in middle, with some long setae; tip triangular, not sharp (Fig. 3 A, B View Figure 3 ) (vs. G 1 stout, terminal segment relatively short, c. 0.3-0.35 times of subterminal segment, subterminal segment gently tapering towards terminal segment; figs 31 c – f, 33 a, b, 35 c – f, 33 d – e, Bahir and Yeo 2007).

Genus Vela is closely related to the new genus, though there are some distinct morphological features that easily separate these two genera. The epigastric cristae is smooth in Vela (fig. 46 a, Bahir and Yeo 2007), while it is distinctly rugose in Patithelphusa gen. nov. (Fig. 2 A View Figure 2 ); postorbital cristae and epigastric cristae are confluent (fig. 46 a, Bahir and Yeo 2007), however postorbital cristae and epigastric cristae are not confluent in Patithelphusa (Fig. 2 A View Figure 2 ); sixth somite of the male pleon distinctly longer than broad (figs 45 B, 46 c, Bahir and Yeo 2007), however sixth somite broader than long in Patithelphusa (Fig. 2 E View Figure 2 ); branchial region relatively swollen (fig. 46 a, Bahir and Yeo 2007), while branchial region gently convex in Patithelphusa gen. nov. (Fig. 2 A View Figure 2 ); G 1 terminal segment cone shaped, 0.4 times of subterminal segment, inner margin straight, outer margin convex in middle (Fig. 3 A, B View Figure 3 ) (vs. G 1 terminal segment more slender and long, 0.45-0.5 times of subterminal segment, outer margin not convex; figs 45 c – e, 47 b – e: Bahir and Yeo 2007).