Priolepis melanops, Bogorodsky, Sergey V., Suzuki, Toshiyuki & Mal, Ahmad O., 2016

Bogorodsky, Sergey V., Suzuki, Toshiyuki & Mal, Ahmad O., 2016, Description of a new species of Priolepis (Perciformes: Gobiidae) from the Red Sea, a new record of Priolepis compita, and a distributional range extension of Trimma fishelsoni, Zootaxa 4150 (2), pp. 168-184 : 171-175

Priolepis melanops n. sp.

Black-faced Reefgoby

Figures 1 & 2 , Table 1

Holotype. SMF 35728, 24.0 mm SL, female, Red Sea, Saudi Arabia, Al Lith , reef wall to depth of about 35–40 m, 27–29 m, St 41, 20°11'N, 40°03'E, 17 November 2014, coll. S.V. Bogorodsky & T.J. Alpermann.

Diagnosis. Priolepis melanops n. sp. differs from other species of the genus in the following combination of characters: dorsal-fin rays VI + I,9, second spine of first dorsal fin longest but not elongate; anal-fin rays I,8; pectoral-fin rays 14–15, all rays unbranched; longitudinal scale series 25; no scales on head or predorsal midline, side of nape scaled; interorbital shallowly concave, bony width 46% of pupil diameter; developed transverse pattern of sensory papillae rows on cheek; interorbital space with anterior and posterior transverse rows of papillae; pelvic fins mostly separated with height of basal membrane between innermost pelvic-fin rays 10.7% of length of fifth ray; fifth pelvic-fin ray unbranched, its length 47% length of fourth ray; body and most head brownish orange densely covered with melanophores; snout, lips, chin, and chest black; iris black; and fins translucent with narrow black stripe along base of first and second dorsal fins.

Description ( Fig. 1 ). Body somewhat compressed, not slender, tapering posteriorly, body depth at pelvic-fin origin 3.9 in SL. Head more or less rounded in cross section, head length 3.2 in SL. Cheeks not prominent. Snout short, with moderately sloping profile, rounded in dorsal view, its length 5.3 in head length. Mouth oblique, lower jaw protruding slightly beyond, with jaws forming an angle of 50° to body axis; maxilla reaching to below anterior fourth of eye, upper jaw length 2.8 in head length. Eyes large, elevated above head profile, eye diameter 2.6 in head length. Interorbital shallowly concave, without postorbital trough or trench; bony interorbital width 46.0% pupil diameter. Suborbital region between eye and upper lip moderately narrow, about one-fourth of eye diameter.

Anterior nares with short tube about one nostril diameter above upper lip; posterior nares a pore-like opening with low raised rim, about one nostril diameter from anterior nares, nasal sac slightly raised. Gill opening moderately broad, extending forward to below between posterior margin of eye and posterior margin of preopercle. Medial face of gill rakers on first gill arch with spicules, GR 5 + 15.

Dentition. Teeth in upper jaw conical, slightly curved, front of jaw with outer row of close-set, enlarged teeth followed by 3 or 4 irregular inner rows of small teeth; sides of jaw with two rows of teeth, progressively narrowing to one row to end of jaw, teeth of outer row larger than those in inner rows and widely-spaced. Front of lower jaw with four large canines on each side of symphysis (outer tooth of each pair twice length of inner tooth), and outer row of seven, enlarged conical teeth medially, followed by two or three, irregular, inner rows of small conical teeth; teeth on sides of jaw small, biserial, those in inner row a little larger than in outer.

Fins. Dorsal fin VI + I,9; first dorsal fin separated from second by a short distance; anal-fin rays I,8; pectoralfin rays 15/14, all rays unbranched; segmented caudal-fin rays 9 + 8; branched caudal-fin rays 6 + 5. Dorsal- and anal-fin rays branched, except first ray in each fin. Dorsal-fin origin half pupil diameter behind vertical through pelvic-fin insertion; first dorsal fin low, subequal in height to second, without filamentous spines, second spine longest, but not elongate, its length 1.6 in head length, reaching to base of spine of second dorsal fin when adpressed; fourth and fifth dorsal-fin spines not extending beyond others when fin adpressed. Pectoral fins reaching to below base of second ray of second dorsal fin. Pelvic fins mostly separated, connected by a thin membrane, the height of basal membrane between innermost pelvic-fin rays 10.7% of length of fifth ray ( Fig. 1 C), no frenum; first four rays each with two terminal tips; fifth ray unbranched, 47% of fourth ray in length; fourth ray longest, reaching posteriorly to base of first segmented ray of anal fin when adpressed. Caudal fin truncate.

Squamation. Body scales ctenoid, except for small cycloid scales on belly, prepectoral, and prepelvic areas. Longitudinal scale series 25; transverse scales counted back 7. No scales on head or midline of predorsal area; side of nape with ctenoid scales, extending forward to above posterior margin of preopercle; prepectoral area with cycloid scales embedded in skin (only one scale visible through skin); prepelvic area fully covered with small cycloid scales but most scales missing and scale pockets abraded.

Head papillae pattern. Pattern of sensory papillae shown in Fig. 2 . Papillae on cheek immediately below eye in six transverse rows, each row with 3–5 papillae, except fifth row interrupted into upper segment with three papillae and lower segment with five papillae, the lower segment below row b. Longitudinal papillae row d ends before fifth transverse row. Interorbital area with anterior and posterior transverse rows at level of pupil, each with four papillae. Vertical rows incorporating elements of rows a (in part), c, and cp, the numbers (in parentheses) in each of remaining rows as follows: a (2), b (6), cs (6), d (9), d’ (10), ea (14), ep (15), f (9), g (4), ia (7), ip (10), m (1), n (9), o (1), ot (14), oi (5), os (2), p (7), r (6), s (1), u (4), x (4), and z (4).

Coloration of freshly collected material (based on photo of holotype - Fig. 1 A). Body and head, except snout and gular region, brownish orange, densely covered with melanophores, more so on cheek and caudal-fin base; abdomen yellowish orange, with fewer melanophores; caudal-fin base dark brownish orange; snout, lips, cheek anteriorly, chin, free margin of branchiostegal membrane and chest black; iris black; dorsal and anal fins with translucent membranes, spines and soft rays reddish brown; black stripe along each base of dorsal and anal fins, those in dorsal fins very obvious; pectoral fins with translucent membranes; pelvic fins with few melanophores in membranes; caudal fin translucent with grayish rays in basal half and reddish rays in posterior half.

Coloration of preserved material ( Fig. 1 B). Body and most head pale brown densely covered with melanophores, less pigmented on abdomen; anterior half of head (face) black. Fins translucent except for pigmented rays on basal half of caudal fin; dark brown stripe along each base of dorsal and anal fins. Iris deep blue.

Distribution and habitat. Priolepis melanops n. sp. is currently known only from the central Red Sea, Saudi Arabia, close to Al Lith. The specimen was found in a small cave in the wall of seaward reef at a depth of 27–29 m, the wall extending to a depth of 35 m. An individual of presumably the same species was observed by the first author inside wreck “Umbria”, at Port Sudan, at depth of 28 m.

Etymology. From the Latin melanops referring to the black face — black snout, lips, and chin.

Generic placement. Winterbottom & Burridge (1989) separated Priolepis and Trimma on three primary features: gill opening extending usually to below posterior preopercular margin in Priolepis (from below the posterior preopercular margin to below the eye in Trimma ); the presence of spicules on the medial surface of the gill rakers of the first arch (no spicules in Trimma ), and the presence of vertical bars at least on the head in Priolepis (typically absent in Trimma ). Hoese et al. (2015) noted that Priolepis possess enlarged canine teeth in front of the upper jaw. Spicules on the medial face of the gill rakers of the first gill arch in P. melanops n. sp. confirm its generic placement. The new species could be assigned to Trimma based on: absence of bars on head and body, moderately broad gill opening, extending forward to below posterior margin of preopercle, no canines in upper jaw, and short fifth pelvic-fin ray (about half length of fourth ray). However, the single specimen P. melanops n. sp. shares with some Priolepis spp. the possession of anterior and posterior transverse interorbital papillae rows, each with four papillae, and a fifth transverse papillae row on cheek that is separated into two segments, the lower segment lying below longitudinal row b (see Winterbottom & Burridge, 1992). No Trimma species are known with transverse interorbital papillae rows except T. nauagium Allen, 2015 , T. xanthochrum Winterbottom, 2011 , and T. yoshinoi Suzuki, Yano & Senou, 2015 , which may have 2 or 3 papillae in transverse rows. There are only a few species of Trimma with developed transverse papillae pattern on cheek. However, even when developed, the fifth vertical row of papillae on the cheek always forms a single line, and is not interrupted into two separate lines by longitudinal row b. The new species is accordingly assigned to the genus Priolepis on the basis of specific features of cephalic papillae pattern and the possession of spicules on the gill rakers of the first gill arch.

Remarks. The genus Priolepis is divided into three groups ( Winterbottom & Burridge, 1992, 1993a, 1993b): species possessing a developed transverse pattern of cheek papillae and with predorsal scales, species possessing a reduced transverse pattern of cheek papillae but without predorsal scales, and species possessing a reduced transverse pattern of cheek papillae and with predorsal scales. Based on its papillae pattern Priolepis melanops n. sp., could be assigned to the former group, containing nine species: P. aithiops Winterbottom & Burridge, 1992 , P. akihitoi Hoese & Larson, 2010 , P. anthioides ( Smith, 1959) , P. fallacincta Winterbottom & Burridge, 1992 , P. goldshmidtae Goren & Baranes, 1995 , P. profunda ( Weber, 1909) , P. randalli Winterbottom & Burridge 1992 , P.

sticta Winterbottom & Burridge, 1992, and P. winterbottomi Nogawa & Endo, 2007 . Priolepis melanops n. sp., however, rather forms a fourth group characterized by a developed transverse papillae pattern and no predorsal scales in the midline. It differs from Indo-Pacific members of the genus, descriptions of which were provided in several publications (e.g. Winterbottom & Burridge, 1992, 1993a, 1993b, 1993c; Goren & Baranes, 1995; Nogawa & Endo, 2007; Hoese & Larson, 2010), in its distinctive colour pattern, with the body and most head brownish orange and densely covered with melanophores, except for a black snout and gular region, and translucent fins with a black stripe along the base of the first and second dorsal fins.

Almost all species of Priolepis are characterized by bars at least on the head; only P. aithiops is uniform in colouration. In addition to its unique colouration, P. melanops n. sp. differs from P. aithiops in having 14–15 pectoral-fin rays, and no scales on the head or the predorsal midline, versus 16–18 pectoral-fin rays, and opercle and predorsal midline scaled in P. aithiops . Two other Priolepis species may have indistinct bars in life: P. agrena Winterbottom & Burridge, 1993 and P. psygmophilia Winterbottom & Burridge, 1993 . Priolepis melanops n. sp. is easily differentiated from P. agrena in possessing developed transverse head papillae pattern and no predorsal scales, versus reduced pattern of cheek papillae and 12–15 predorsal scales, and from P. psygmophilia in having fewer soft rays in dorsal and pectoral fins (9 and 14–15 respectively versus 10–12 and 19–21 rays respectively), and in having a developed transverse papillae pattern on the cheek versus a reduced papillae pattern in P. psygmophilia . At present five species of the genus are known from the Red Sea: P. ci nct a, P. compita Winterbottom, 1985 , P. goldshmidtae , P. randalli and P. semidoliata . Priolepis melanops n. sp. can easily be differentiated from the Red Sea congeners by its distinctive colour pattern and by a combination of the developed transverse papillae pattern on cheek, the count of rays in fins, and in lacking scales on the head and the predorsal midline area.

Priolepis melanops n. sp. resembles Trimma flavatrum Hagiwara & Winterbottom, 2007 , known from the Western Pacific, which has 12–15 pectoral-fin rays, 22–26 longitudinal scale series, 7–9 anterior and 6–9 posterior transverse scale rows, a shallow concave interorbital region, no postorbital trench or trough, no elongate spines in first dorsal fin, unbranched pectoral-fin rays, an unbranched fifth ray of the pelvic fin, length of fifth pelvic-fin ray 40−65% length of fourth ray, scales on side of the nape, head and body largely uniform, and narrow black band along base of first and second dorsal fins. Priolepis melanops n. sp. differs from T. flavatrum in having no predorsal scales in the midline (versus 7–8 such scales in T. flavatrum ), developed transverse pattern of sensory papillae rows below eye (versus reduced papillae pattern), 9 second dorsal-fin rays (versus 7–8), no scales on the cheek and opercle (versus present), gill opening moderately broad, extending forward to below the posterior margin of the eye and the posterior margin of the preopercle (versus gill opening broad, extending to below mideye), height of the basal membrane between the innermost pelvic-fin rays 10.7% of the length of the fifth ray (versus absent), no canine teeth in the upper jaw (versus canine teeth present), uniform brownish orange body becoming darker at the caudal-fin base only and head brownish orange with black “face” (versus the head and anterior part of the body uniform yellow becoming progressively darker from posterior half of body below the second dorsal fin or from the anterior caudal peduncle), and first and second dorsal fins translucent with a narrow black stripe along the base (versus black stripe followed by a broader yellow band, and distal half either bluish or translucent (see Hoese & Winterbottom, 2015).

Figures

FIGURE 1. Priolepis melanops, n. sp., SMF 35728, holotype, female, 24.0 mm SL, Al Lith, Saudi Arabia, Red Sea A: freshly collected; B: preserved; C: ventral view of region between pelvic and anal fins; red line indicates basal membrane, yellow lines show fourth and fifth pelvic-fin rays. Photos by S. V. Bogorodsky (A) and T. Suzuki (B, C).

FIGURE 2. Priolepis melanops n. sp., SMF 35728, holotype, cephalic sensory papillae of head. Dorsal (top), lateral (middle) and ventral (bottom) views of head. Dots represent the sensory papillae; AN = anterior nares, PN = posterior nares; arrow shows position of lower end of gill opening. Photo and drawing by T. Suzuki.