Perulibatarchus aquilonarius Greenfield 2005

Bineesh, K. K. & Greenfield, David W., 2011, Redescription of the Indian toadfish Perulibatrachus aquilonarius Greenfield (Teleostei: Batrachoididae), Zootaxa 2886 (1), pp. 63-68 : 63-67

Perulibatarchus aquilonarius Greenfield 2005

( Figs. 1–4 )

Diagnosis. A species of Perulibatrachus with a wide head (37.1–43.6%SL), 17–18 dorsal-fin rays, 13 anal-fin rays, 21–23 pectoral-fin rays, a shallow, funnel-shaped pocket in the upper pectoral-fin axil, and the body and fins covered with small dark spots.

Description. Standard length of holotype (CAS-SU 41322) 191.4mm; SL of CAS 231007, 236.5mm. Dorsalfin elements III-17 (18); anal-fin rays 13 (13); pectoral-fin rays 21 (23); head length 45.0 (41.9); head width 43.6 (37.1); head depth 25.3 (29.1); bony interorbital width 9.5 (8.6); orbit diameter 7.6 (8.1); snout length 8.8 (8.3); upper jaw length 25.9 (24.6); mouth width at rictus 36.1 (30.3); first predorsal-fin distance 42.1 (41.3); second predorsal-fin distance 61.6 (56.6); preanal-fin distance 72.5 (67.2); greatest body depth 25.2 (31.3); caudal-peduncle depth 9.8 (9.3); caudal-peduncle length 13.6 (10.1); first dorsal-fin base length 11.4 (11.3); second dorsal-fin base length 39.6 (41.2); anal-fin base length 21.5 (22.4); caudal-fin length 22.7 (24.6); pectoral-fin length 25.0 (28.6); pelvic-fin length 26.7 (27.2); distance between pelvic-fin bases 15.3 (14.4).

Head moderately depressed and wide, eyes medium in size and not raised above head profile. Pectoral-fin axil with a shallow, funnel-shaped pouch in upper half, glandular tissue present in rest of axil and on sides under pectoral fins. Some glandular tissue present on inner surface of pectoral fins. Body with small scales extending from middle of first dorsal fin base to caudal-fin base, covering most of sides. Scales extending forward on ventral surface to middle of pectoral fins, becoming more embedded. Three lateral lines, each pore with two short skin flaps: the upper one originating above upper opercular spine, running posteriorly in a straight line and then curving up over pectoral fin to run along the dorsal-fin base to its end, with 36–41 pores present. A short lateral line with 12 obvious pores on the center of the side running from below the end of the upper lateral line onto the caudal-fin base. A few scattered pores in advance of this from below the fifth dorsal-fin ray back to the obvious short line. The lower lateral line, with 14–17 pores, runs along the anal-fin base. Head with many black cirri. A row of six sets of double cirri, each flattened and leaf-like, extending across nape. Three additional, similar cirri on each side just behind eye and onto top of head. Entire interorbital area down to snout covered with small, single, pointed cirri. Posterior nostrils large, openings edged with many small cirri. Two small pores, each with a double set of larger leaf-like cirri centered on snout between posterior nostrils. Anterior nostrils tubular with opening on side; in both specimens nostril on left side with a simple major tentacle, whereas the nostrils on the right have two or three terminal tentacles ( Fig. 1 ). A cluster of multifid cirri surrounds each tubular nostril. Cirrus at distal end of maxilla with many tips. Ventral margin of dentary with numerous cirri. Dorsal surface of neurocranium completely covered with muscles; no exposed bone.

Color of freshly collected specimen (CAS 231007): ( Figs. 2–4 ) Background color of head and body light brown, covered with many small, irregularly shaped, dark brown spots. A darker band of pigment running across back from pectoral-fin base to pectoral-fin base and through first dorsal fin. Another darker band crossing back at middle of second dorsal fin. Pectoral-fin base dark brown to black. Background lighter brown to cream in a line across head between eyes. A series of dark brown to black bars radiating out from around eyes like spokes. Upper and lower jaws covered with dark brown spots as on body. Barbels around jaws white. Tentacles on top of head behind eyes dark brown. All fins covered with small, dark brown spots.

Color of preserved specimen (CAS 231007): Background color gray, overlaid by brown color pattern as in fresh specimen. Ventral surface, not visible in photograph of fresh specimen, is gray, lacking distinct spots. Underside of head gray extending posteriorly to pectoral-fin base. Area from pelvic-fin bases posterior to anus slightly darker grey. Area around anus white and extending up onto lower half of sides as a bar. Skin around pelvic-fin spine white; skin around rays dark grey.

Comparisons. In the original comparison of P. aquilonarius with other Perulibatrachus species the width of the head was said to be greater than in P. elminensis and P. rossignoli , both West African species and P. kilburni from east Africa. The narrower head measurement of the second specimen of P. aquilonarius is close to the upper limit for P. elminensis (37.1 vs 37.9) and below the greatest width for P. rossignoli (37.1 vs. 40.9). Perulibatrachus kilburni has a head width of 29.7. Perulibatrachus aquilonarius still, however, differs from P.elminensis in having fewer anal-fin and pectoral-fin rays. Additionally, now that the fresh coloration is known, P. aquilonarius clearly differs from P.elminensis in fresh coloration by having the body and fins covered with small dark spots ( Figs. 2–4 ), whereas P. elminensis has a network of irregular brown lines covering the body ( Fig. 5 ). It no longer differs from P. rossignoli in the number of pectoral-fin rays, but still differs in having fewer dorsal-fin rays and also in color: Whereas P. aquilonarius is covered with many small dark spots, P. rossignoli has several large blotches on the body and no spotting on the fins ( Fig. 6 ).

Remarks. The second specimen was collected off the coast of Tuticorin in the Gulf of Mannar at a depth of 10–30m by a gill net. The holotype was collected at Madas to the north of Tuticorin, also along the southeast coast of India. This species may prove to be more widespread along the Indian coast.

Figures

FIGURE 1. Right tubular nostril of Perulibatrachus aquilonarius, CAS 231007. Dark spot is nasal opening. Drawing by D.W. Greenfield.

FIGURE 2. Perulibatrachus aquilonarius, CAS 231007, dorsal view. Photograph by K.K. Bineesh.

FIGURE 3. Perulibatrachus aquilonarius, CAS 231007, front view of head. Photograph by K.K. Bineesh.

FIGURE 4. Perulibatrachus aquilonarius, CAS 231007, side view of head. Photograph by K.K. Bineesh.

FIGURE 5. Perulibatrachus elminensis, 21cm TL, Ivory Coast. Photograph by A. Oddgeir.

FIGURE 6. Perulibatrachus rossignoli, 20 cm TL, Ghana. Photograph by A. Oddgeir.