Ptereleotris cyanops, Kodeeswaran & Praveenraj, 2020

Kodeeswaran, P. & Praveenraj, J., 2020, A new species of dartfish of the genus Ptereleotris (Teleostei: Gobiidae) from the East Coast of India, Zootaxa 4861 (3), pp. 423-428 : 424-428

Ptereleotris cyanops , new species

( Figures 1–4 , Table 1)

Holotype: NBFGR /GOBPCYA, female, 75.5 mm SL, India: Tamil Nadu, Chennai Coast, Royapuram Fishing Harbour (13°07’24.49”N; 80°17’52.20”E), collected from trawl bycatch, P. Kodeeswaran & J. Praveenraj, 07 October 2019.

Paratypes: NBFGR /GOBPCYA.1–3, 3 ex., 78.5–87.4 mm SL ; CIARI /MF-06, 75.4 mm SL; same collection data as holotype .

Diagnosis. Ptereleotris cyanops is distinguished from all known species of Ptereleotris by the following combination of characters: caudal fin slightly truncate with 17 (9+8) total principal caudal rays, the 5 th and 13 th branched rays greatly prolonged as filaments; discontinuous dorsal fin, the interdorsal space about the width of orbit diameter; second dorsal and anal fin not elevated anteriorly; 7+17 gill rakers; absence of black bar at base of pectoral fin; presence of orange horizontal stripe on posterior body to caudal fin base.

Description. Dorsal rays VI + I, 27; anal rays I, 27; dorsal and anal rays branched only distally, except the last, branched to base; pectoral rays 22–23, the upper one and lower two unbranched; pelvic rays I, 4; total principal caudal rays 17 (9+8), 7+6 branched rays, the 5 th and 13 th branched rays greatly prolonged as filaments; scales in longitudinal series 168–169; gill rakers 7+17; total vertebrate including urostyle 26; dorsal pterygiophore formula 3-32010, the first three pterygiophores are inserted between neural spines 3 and 4, the next two are between neural spines 4 and 5, followed by a vacant interneural space between neural spines 5 and 6, and a single pterygiophore between neural spines 6 and 7 ( Figure. 4 ).

Morphometric data are presented in Table 1. Body elongated and laterally compressed, depth at origin of pelvic fin 6.2 (6.6–8.5) in SL and width 1.6 (1.3–1.4) in body depth; head length 5.6 (5.6–6.5) in SL; snout 3.1 (3.0–3.5) in HL; orbit diameter 2.6 (2.6–3.0) in HL; bony interorbital width 3.1 (3.0–4.3) in HL; caudal peduncle little deeper than length, depth 1.7 (1.8–2.2) in HL.

Dorsal fin with a wide interdorsal space between spines and rays, its width around that of orbit diameter 5.9 (5.4–6.6) in HL ( Figure. 3 ); spinous dorsal fin deeply curved posteriorly and lower than the dorsal rays; first dorsal-fin spine 1.7 (1.6–2.0) in HL, fifth spine longest 1.7 (1.2–1.3) in HL, first spine of the second dorsal fin about two-third length of the first soft ray and half the length of longest dorsal ray, twenty-first dorsal soft ray longest 1.2 (0.8–1.2) in HL. Anal-fin origin at line from third dorsal soft ray; anal spine 2.5 (1.7–2.9) in HL; longest anal ray 1.4 (1.0–1.4) in HL; caudal fin slightly truncate, the 5 th and 13 th branched rays extremely filamentous, its length 1.8 (1.3–1.8) in SL; caudal-fin length 3.7 (3.6–4.0) in SL; pectoral fin 1.4 (1.2–1.3) in HL; pelvic fin equals or slightly longer than HL.

Mouth oblique forming a 75° angle to axis of body, lower jaw strongly projecting; maxilla reaching vertical through anterior edge of pupil. Upper-jaw length 2.3 (2.3–2.6) in HL. No free posterior margin to preopercle, gill opening extending forward to a vertical at dorsoposterior edge of preopercle. No barbel on chin, instead a low median fleshy ridge that narrows posteriorly as thin ridge, ending in a right angle in line with a vertical at middle of eye. Each side of upper jaw with outer row of ten large, recurved, canine teeth, posterior ones notably small; front of upper jaw with inner band of two irregular rows of small incurved teeth, narrowing to single row posteriorly. Front of lower jaw with two rows of teeth, outer row with three pairs of canines, and inner row of four widely spaced canines, two at front of jaw and two at sides, separated at front of jaw by two irregular rows of small teeth, continuing as single row posteriorly as small canines. Scales cycloid, small, partially to fully embedded, mainly non-imbricate; prepectoral and prepelvic areas with small embedded scales. Head scaleless, including nape; no scales on fins except for small embedded scales on about basal half of caudal fin. Scales at caudal peduncle are closely set with weak ctenii. Anterior nostril a short tubule at level of upper edge of pupil; posterior nostril elliptical, dorsoposterior to anterior nostril, directly above anterior edge of orbit.

Coloration. When fresh ( Fig. 1 ), body bluish-grey, an orange stripe posteriorly on lower side of body extending up to basal rays of caudal fin, belly whitish. Bluish shades on snout extending over dorsal margin of eye to operculum, ventral margin of eye rim with blue shade, iris silvery. A bluish stripe from dorsal of eye rim to preopercle. Pectoral-fin base iridescent blue; pectoral fin translucent; 1 st and 2 nd dorsal, anal fin beige, distal margins orange. Anal fin with a horizontal blue strip towards base. Caudal fin violet to bluish. In preservative ( Figs. 2–3 ), body entirely tan to beige with no any dark markings; all fin rays beige to tan, tip of dorsal anal, and caudal fin dark-brown, fin membrane translucent.

Distribution. Chennai, South east coast of India, Bay of Bengal, Indian Ocean. The species was collected from a depth of 30–40 m along the Chennai coast at a distance of 20 to 60 km, which stretches from Mahabalipuram in south to Ennore in Northern Tamil Nadu.

Etymology. The species epithet ‘cyanops’ is derived from Ancient Greek cyanos (κυάνεος) = blue and ops (ὤψ) = eye, an allusion to the blue iridescent bands on orbit of the eyes.

Comparison. Ptereleotris cyanops bears some general resemblance to P. microlepis on the basis of meristic, morphometric, and coloration details, but is readily distinguished from it by the absence of black bar at base of pectoral fin (vs. presence of a narrow black bar on lower half of pectoral fin base); in having a slightly truncate caudal fin with the 5 th and 13 th branched rays prolonged as filaments (vs. slightly emarginated caudal fin with absence of any caudal filaments), in having the second dorsal and anal fin not elevated anteriorly (vs. second dorsal and anal fin slightly elevated anteriorly), and in having fewer gill raker count (24 vs. 25–30). Ptereleotris cyanops differ from other caudal filament bearing congeners viz., P. arabica Randall & Hoese, 1985 and P. hanae ( Jordan & Snyder, 1901) by the absence of chin barbel (vs. present in both), in having a wide interdorsal space about the width of orbit diameter (vs. the first and second dorsal fin appearing almost continuous with a shallow connecting membrane between the spine and ray). The new species further differs from P. arabica in having the 5 th and 13 th branched rays prolonged as filaments compared to the 3 rd and 11 th branched rays prolonged as filaments, a longer pelvic fin (17.7–18.8 vs. 13.1–15.5% SL), and by fewer gill raker count (24 vs. 27–31); and differs from P. hanae in having only 2 caudal filaments (vs. 2–6 caudal filaments), and more anal rays (27 vs. 22–25).

Ptereleotris cyanops differs from P. evides in having a slightly truncate caudal-fin with filaments extending from the 5 th and 13 th branched caudal rays (vs. emarginated caudal-fin with absence of any fin-ray extension), absence of scales on top and sides of nape (vs. presence of tiny scales on top and sides of nape). Ptereleotris cyanops differs from P. brachyptera Randall & Suzuki, 2008 , P. caeruleomarginata , P. carinata Bussing, 2001 , P. crossogenion Randall & Suzuki, 2008 and P. randalli Gasparini et al., 2001 , in having more second dorsal and anal rays (I, 27 vs. I, 20–25; 27 vs. 18–24). The new species differs from P. heteroptera (Bleeker 1855) , P. lineopinnis (Fowler, 1935) and P. monoptera Randall & Hoese, 1985 , in possessing fewer second dorsal and anal rays (I, 27 vs I, 29–39; 27 vs. 27–37); and differs from P. grammica Randall & Lubbock, 1982 and P. uroditaenia Randall & Hoese, 1985 , in having a noticeably shorter first dorsal fin, shorter in height compared to the second dorsal fin (vs. first dorsal fin height twice high as second dorsal fin), and more anal rays (27 vs. 24–26). It differs from P. melanopogon Randall & Hoese, 1985 , P. rubristigma Allen et al., 2012 and P. zebra (Fowler, 1938) by the absence of barbels on chin (vs. present) and more anal rays (27 vs. 23–25); and from P. kallista Randall & Suzuki, 2008 , by more anal rays (27 vs. 25–26), and in having the first dorsal fin being relatively shorter than the second one (vs. first dorsal fin about twice height of second dorsal fin).

Remarks. Pterelotris cyanops were collected from the bycatch landings of single day trawlers operated at the depth of 30–40 m along the Chennai coast at the distance of 20 to 60 km, which stretches from Mahabalipuram in south to Ennore in Northern Tamil Nadu, Bay of Bengal, Eastern Indian Ocean. This region is characterized by natural boulders and coral reefs ( Vaz 1996). We presume that P. cyanops should have been collected from such habitats, and may represent a species endemic to southeast coast of India.

Photographs examined. Ptereleotris arabica: NMNH Extant Specimen Records (FIN030815, FIN030815B, FIN030816 Slide 120 mm and CD No. 034-1003)

Ptereleotris hanae: CAS Ichthyology Collection Database (CAS-SU 6444)

Figures

FIGURE 1. Ptereleotris cyanops, Holotype, NBFGR/GOBPCYA, 75.5 mm SL (colouration prior to preservation).

FIGURE 2. Ptereleotris cyanops, A. Holotype, NBFGR/GOBPCYA, 75.5 mm SL, female; B. Paratype, NBFGR/GOBPCYA.1, 78.5 mm SL, male.

FIGURE 3. Ptereleotris cyanops, holotype, NBFGR/GOBPCYA, 75.5 mm SL, showing wide interspace between first and second dorsal fin.

FIGURE 4. Radiograph of Ptereleotris cyanops, A. Holotype, NBFGR/GOBPCYA, 75.5 mm SL, B. Paratype, NBFGR/GOB- PCYA.1, 78.5 mm SL.