Acanthophrys keeae, Ng & Prema & Ravichandran, 2024

Ng, Peter K. L., Prema, Mani & Ravichandran, Samuthirapandian, 2024, Descriptions of new and rare crabs associated with coral rubble and sponges from Kanyakumari, southeastern Arabian Sea, southern India (Decapoda: Brachyura: Epialtidae and Pilumnidae), Zootaxa 5476 (1), pp. 325-341 : 327-329

Acanthophrys keeae n. sp.

( Figs. 2–4)

Type material. Holotype: male (cw 7.6, cl 13.4, pcl 9.9 mm), CASAU-CR-2021-1022, Manakudy fish landing centre, Kanyakumari district, Tamil Nadu, southern India, Southeastern Arabian Sea, 8°05′29.8′′N, 77°29′02.9′′E, 50–60 m, in coral rubble, coll. M. Prema, 5 November 2021.

Etymology. The species is dedicated to late Dr. Ng Ngan Kee from the National University of Singapore, who passed away in July 2022.

Diagnosis. Carapace pyriform; dorsal surface covered by large low, rounded tubercles on anterior half of carapace, without sharp tubercles or spines; branchial region with low tubercles and granules and larger submedian tubercle; median gastric regions with 3 low tubercles, no spines; cardiac region elevated but without spine; intestinal region raised with median tubercle; hepatic region with small median tubercle ( Fig. 2A–E); pseudorostral spines long, divergent ( Fig. 2A–C); proepistome distinctly deflexed, margins carinate ( Fig. 2G); supraorbital eave laterally expanded, distinctly bilobed, antorbital and preorbital lobes subequal in size and length, tips of lobes rounded ( Fig. 2B–D); postorbital spine proportionately longer, extending well beyond margin of supraorbital eave, inner margin with prominent median tubercle ( Fig. 2B, C); outer margin of basal antennal article sinuous with median part concave ( Fig. 2F–H); pterygostomial region with 2 large tubercles ( Fig. 2F); exopod of third maxilliped wide ( Figs. 2F, 4A); margins of merus of cheliped smooth, unarmed ( Fig. 4C); ambulatory legs relatively short, flexor margin of dactylus with 8 or 9 short stout spines ( Fig. 4D); male anterior thoracic sternum distinctly elongate, with sternites 3 and 4 constricted to form neck-like structure ( Fig. 3A); male pleon distinctly triangular in shape, pleomeres 3 and 4 extremely wide, telson lingulate, elongate ( Figs. 3A, 4E); G1 relatively straight, slender, distal two-thirds of G1 almost straight with distal part clearly tapering ( Figs. 3B–D, 4F–L).

Colouration. Not known.

Remarks. The most distinctive character of Acanthophrys keeae n. sp. is the bilobed supraorbital eave with the antorbital and preorbital lobes subequal in size and length, a character it shares with A. costatus described from Lord Howe Island, eastern Australia. The other Acanthophrys species have the antorbital lobe much larger than the preorbital lobe. Acanthophrys keeae n. sp., however, can be separated from A. costatus by the tips of the ant- and preorbital lobes of the supraorbital eave being distinctly rounded ( Fig. 2B–D) (vs. tips sharp in A. costatus ; Griffin & Tranter, 1986: fig. 31h); the postorbital spine is proportionately longer, extending well beyond the margin of the supraorbital eave ( Fig. 2B, C) (vs. postorbital spine shorter, reaching just beyond the margin of the supraorbital eave in A. costatus ; Griffin & Tranter, 1986: fig. 31h); the gastric regions are covered with many low rounded tubercles ( Fig. 2B–E) (vs. gastric regions smoother in A. costatus ; Griffin & Tranter, 1986: fig. 31h); the branchial region is less prominently inflated and narrower, with only low tubercles on the surface ( Fig. 2A, B) (vs. branchial region more inflated, wider, with low sharp spines and tubercles in A. costatus ; Griffin & Tranter 1986: fig. 31h); the outer margin of the basal antennal article is sinuous with the median part concave ( Fig. 2F–H) (vs. margin almost straight in A. costatus ; Griffin & Tranter 1986: fig. 31a); the exopod of the third maxilliped is proportionately wider ( Figs. 2F, 4A) (vs. exopod distinctly narrower in A. costatus ; Griffin & Tranter 1986: fig. 31f); the almost smooth merus of the cheliped ( Fig. 4C) (vs. dorsal margin distinctly tuberculated in A. costatus ; Griffin & Tranter 1986: fig. 31d); the male anterior thoracic sternum is distinctly elongate, with sternites 3 and 4 constricted to form neck-like structure ( Fig. 3A) (vs. male anterior thoracic sternum relatively shorter, sternites 3 and 4 not distinctly constricted in A. costatus ; Griffin & Tranter 1986: fig. 31c); the male pleon is more triangular in shape, with pleonal somites 3 and 4 distinctly wider with the telson lingulate and elongate ( Figs. 3A, 4E) (vs. pleonal somites proportionately narrower with telson triangular and shorter in A. costatus ; Griffin & Tranter 1986: fig. 31c); and the distal two-thirds of the G1 is almost straight with the distal part tapering ( Figs. 3B–D, 4F–L) (vs. G1 distally bent with a rounded tip in A. costatus ; Griffin & Tranter 1986: fig. 32a, b).

Distribution. Known only from the type locality.