Genus: Sphoeroides Anonymous [Lacepède], 1798

Species: Sphoeroides pachygaster (Müller & Troschel, 1848)

Synonyms

Liosaccus pachygaster (Müller & Troschel, 1848); Tetrodon pachygaster Müller & Troschel, 1848; Tetrodon cutaneus Günther, 1870; Sphaeroides cutaneous (Günther, 1870); Spheroides dubius von Bonde, 1923; Liosaccus aerobaticus Whitley, 1928; and Thecapteryx lioderma Fowler, 1948.

Material examined: FSIKM-TSp-1,223, 1 Female (SL 189 mm), Arabian Sea, off Kerala, India, Lat. 8°41’ N, Long. 76°06’ E and Lat. 8°44’ N, Long. 76°04’ E at 263 – 310 m depth, March 2019.

Holotype: Sphoeroides (Ranzani) ANSP 109468, 2 nos, 134 – 137 mm, Florida, ANSP 101322 – 1 no, 80.6 mm, Nigeria; ANSP 10478, 11 nos, 117 mm, Mozambique. MNHN 8340 (1, 208), Cape of Good Hope; holotype of Tetraodon laevissimus of Cuvier and Stenometopus laevissimus (Bibron) Troschel and BMNH (2, 183-188), St. Helena.

Syntype: Tetrodon cutaneus Gunther. USNM 168467 (1, 82) Corregidor, Philippine islands. ANSP 75576 (1, 185), Hawaiian Islands, Oahu.

The first diagnostic description of this species was made by Muller and Troschel, however, specimen was missing. Considering the characters available in the record, Shipp 1 reported detailed review by analysing 51 specimens from various museums and synonymised 36 species into single conspecific Sphoeroides pachygaster.

Type localities: Tetrodon (Cheilichthys) pachygaster Muller and Trochel 1848a: 677 (original description, Barbados); Sphoeroides (also Sphaeroides, Spheroids) Pachygaster. Jordan 1886b: 605 Sphaeroides cutaneus: Smith, 1953, Sea Fishes of Southern Africa: 417 pI. 95, fig. 1190; Tetrodon cutaneous: Gunther, 1870, 287 (type locality: St. Helena, Azores); and Spheroides dubius: Von Bonde, 1923, 40, pl. 2, fig. 3 (type locality: off Natal, South Africa, 27 fms).

Description

Inflatable body with rounded snout, nostrils was easily visible with the naked eye (Fig. 1); dorsal surface smooth and without a distinct keel from posterior to eyes. Body entirely smooth and prickles totally lacking, which differentiated S. pachygaster from other species of the genus Sphaeroides. Bands and blotches of spots are present on the body. Interorbital broad and as long as 13 % of SL; pigmentation uniform (Fig. 1), big head and skin without scales. Four large teeth form a beaklike structure with thin lips. Eyes big and oval in shape, vertical and horizontal length almost equal; chin prominent; nasal organ short, papilla erected and nasal pores not equal. Dorsal fin small and situated just above the anal fin with almost same size and shape. Caudal fin slightly concave with white shade on the lower portion. Pelvic fin absent. Dorsal rays 8; anal rays 8; pectoral rays 15 (i,14); caudal fin rays 11(i, 9, i); and vertebrae 19 (9 + 10).

Colouration: Belly white and rough, pectoral fin base black, margin of the pectoral fin white, the ventral side whitish.

DNA sequences: 540 bp of 16S rRNA gene sequences of S. pachygaster was generated and submitted to DNA data Bank of NCBI.