Coryogalops nanus Kovačić & Bogorodsky, 2016

Kovačić, Marcelo, Bogorodsky, Sergey V. & Mal, Ahmad O., 2016, A new species of Coryogalops (Perciformes: Gobiidae) and the first adult record of Feia nympha from the Red Sea, Zootaxa 4097 (3), pp. 341-352 : 344-349

Coryogalops nanus Kovačić & Bogorodsky , sp. nov.

( Figures 1 & 2 , Tables 1 & 2 )

Holotype. SMF 35753 (field number KAU12-102), male, 14.7+ 4.1 mm, Red Sea, Saudi Arabia, Farasan Archipelago, Farasan Island, 16°43.083' N, 42°03.934' E, rubble-sand bottom with shells, 0.5−1 m, coll. S.V. Bogorodsky, 20 February 2012.

Paratype. PMR VP 3048, male, 15.2+ 4.3 mm, Red Sea, Egypt, Dahab, 28°47.759' N, 34°51.393' E, rubblesand bottom with shells, 3 m, coll. S.V. Bogorodsky, 16 November 2012.

Diagnosis. Dorsal-fin rays VI + I,10; anal-fin rays I,9; pectoral-fin rays 12−14, two upper rays with free tips; pelvic fins I,5, joined to form a disc, disc emarginate (the shortest branches of fifth ray about 2/3−3/4 length of longest branches of fourth ray), no pelvic frenum; predorsal area and area at base of first dorsal fin naked; longitudinal scale series 26−29; transverse scale series counted forward 6−7, reaching naked area at first dorsal-fin base; transverse scale series counted backward 7−8; circumpeduncular scale rows 11−12; head with seven transverse suborbital rows of sensory papillae; no tentacle above upper eye margin; anterior nostril tubular, without flap at its tip, posterior nostril pore-like; body semi-translucent with small scattered orange-yellow spots and speckles, spots in predorsal area and a few midlaterally on body containing black dots; a row of internal white spots along ventral part of body above anal-fin base and on caudal peduncle; head and prepectoral area with small scattered orange to yellowish brown spots; first dorsal fin with two broad white bands at base of fin and distally, middle of fin hyaline densely dotted with melanophores; preserved material opaque white to yellowish with sparse melanophores.

Description (all morphometric values and meristics in the text are presented as holotype first and paratype in parentheses). Body moderately elongate, the depth at pelvic-fin and anal-fin origin 5.3 (5.6) in SL, laterally progressively compressed toward caudal peduncle; width at pectoral-fin origin 5.3 (5.1) in SL, 1.0 (0.9) in body depth. Preanal-fin length 1.6 (1.7) in SL, predorsal length 2.6 (2.6) in SL; prepelvic distance 3.3 (3.7) in SL. Head length 3.1 (3.3) in SL; dorsal profile of head slightly convex, with dorsal part of eye projecting above contour. Snout short, with moderately sloping profile, 14.1 (15.2) in SL, 4.5 (4.6) in head length. Eye diameter 10.0 (10.5) in SL, 4.5 (4.6) in head length. Interorbital space very narrow, 42.7 (38.5) in head length. Mouth oblique, terminal, lips anteriorly about equal, maxilla reaching to below mideye, upper jaw length 9.7 (9.8) in SL, 3.1 (3.0) in head length. Both jaws with several, poorly defined, rows of conical teeth. Tongue truncate. Gill opening ending at level of lower base of pectoral fins. Anterior nostril tubular, without flap at its tip, posterior nostril pore-like with slightly raised rim. Caudal peduncle depth 6.7 (6.9) in SL, 2.1 (2.1) in head length; caudal peduncle length 4.7 (4.4) in SL, 1.5 (1.4) in head length.

Fins. First dorsal fin with VI spines, second dorsal fin I,10; anal fin I,9; pectoral-fin rays 14/14 (12/13), all rays branched, two upper rays with free tips; branched caudal-fin rays 13 (12), segmented rays 16; pelvic fins I,5, joined to form a disc, disc emarginate (shortest branches of fifth ray compared to the longest branches of fourth ray: 74.0 (68.7) %), no pelvic frenum. Origin of first dorsal fin at vertical behind pectoral-fin base, spines not elongate, first three dorsal spines equal in length 7.4 (7.0) in SL, 2.4 (2.1) in head length, the remaining spines progressively shorter. Interdorsal space narrow. Spine of second dorsal fin 7.4 (8.0) in SL; fifth to seventh dorsal-fin ray longest and of same length, 7.2 (7.1) in SL, longest rays ending well before base of uppermost caudal-fin rays. Origin of anal fin at vertical through first dorsal-fin soft ray; first anal-fin spine 7.6 (8.9) in SL; eighth (penultimate) anal-fin soft ray longest, its length 7.0 (7.3) in SL. Base of dorsal fins 2.3 (2.4) in SL; anal-fin base 4.2 (4.4) in SL. Caudal fin rounded, its length 3.6 (3.5) in SL, a little shorter than head length. Pectoral fins more or less pointed, ninth ray longest, 3.9 (4.1) in SL. Origin of pelvic fins at vertical to base of pectoral fins, pelvic spine 14.6 (13.6) in SL; pelvic fins short, length 4.3 (4.3) in SL, not reaching anus.

Squamation. Scales large, ctenoid except cycloid scales on belly and behind pectoral-fin base. Head naked; no predorsal scales and no scales on side of nape anterior to a line from posterior end of first dorsal fin to above upper end of pectoral-fin base; no scales on prepectoral and prepelvic areas; no scales on fins except for basal row on caudal fin. Longitudinal scale series 26/27 (28/29); transverse scale series counted forward 7/6 (6/7), reaching naked area at first dorsal-fin base; transverse scale series counted backward 8 (7); circumpeduncular scales 11 (12).

Cephalic sensory systems ( Fig. 2 ). Head with divided anterior and posterior oculoscapular canals with pores σ, λ, κ, ω, α, β, ρ and ρ1, ρ2, respectively, and preopercular canal having pores γ, δ, ε. Rows of head sensory papillae were counted on the right side of the holotype (number of papillae in row first given for holotype) and paratype since the skin surface there was in better condition in both specimens and presented respectively. Low count of relatively larger papillae in all rows: (1) preorbital: snout with four median preorbital rows, row r (2 and 2) at the level of posterior nostril, horizontal row s1 (3 and 2) below pore σ, horizontal row s2 (3 and 2) below s1 and vertical s3 (1 and 1) more medially above upper lip. Lateral series c in four parts: superior (c2) in two short rows between anterior and posterior nostril (2+2) in holotype or just two single papillae in paratype; middle (c1) (2 and 2) starting at anterior nostril; inferior rows, upper horizontal c2 (2 and 2) and lower horizontal c1 (1 and 1) placed anteriorly and posteriorly at upper lip; (2) suborbital: seven transverse suborbital rows of sensory papillae (1−7), all short, rows 2 and 3 start upwards distant from eye, rows 4 to 6 start upwards close to eye, only row 6 consists of superior and inferior section, inferior section of row 6 well developed, extended to level of row d (1: 5 and 5, 2: 3 and 3, 3: 3 and 3, 4: 4 and 2, 5: 3 and 2, 6s: 4 and 2, 6i: 6 and 6, 7: 2 and 1). Longitudinal row b (3 and 2) a short row extending forwards to row 6. Longitudinal row d (6 and 5) with poorly developed supralabial part; (3) preoperculomandibular: external row e (9+8 and 9+4) and internal row i (6+6 and 6+6) uniserial and divided into anterior and posterior sections; row f with 3 (holotype) or 2 (paratype) papillae; (4) oculoscapular: anterior longitudinal row x1 (5 and 5) above pore ρ, not extending forwards to pore β, posterior longitudinal row x2 (2 and 2) above pore ρ2; row z (4 and 4) with lower end above pore γ, row q as 2 papillae behind pore ρ, vertical row trp (2 and 2) behind x1 and in front of pore ρ1, row y single papilla behind and above pore ρ2. Axillary vertical rows as1 (4 and 3), as2 (2 and 3), as3 (3 and 2) developed, row la1 single papilla above as2, row la2 single papilla above as3; (5) opercular: transverse row ot (8 and 7); superior longitudinal row os (3 and 3); and inferior longitudinal row oi (2 and 2); (6) anterior dorsal: anterior transverse row n (3 and 3) behind pore ω, transverse row o (3 and 2) distant from fellow in dorsal midline; longitudinal row g (3 and 2) not reaching row o, longitudinal row m absent, longitudinal row h (3+3 and 2+3) divided in posterior and anterior parts.

Coloration of freshly collected material, based on photos of holotype and paratype ( Figs.1 A & 1C). Body semi-translucent with visible vertebrae and silvery peritoneum, with small scattered orange-yellow spots and speckles, those in predorsal area and few midlaterally on body contain black dots; a row of internal white spots along ventral part of body above anal-fin base and on caudal peduncle; scales narrowly outlined with whitish; small white iridescent spots and blotches on surface of body visible through translucent scales; prepectoral area with a few dark orange-yellow spots. Head with small scattered orange to yellowish brown spots covering nape, opercle, preopercle, cheek, and snout; reddish color from gills visible through opercle; eyes silvery white with narrow orange-yellow bands radiating from black pupil. First dorsal fin with two broad white bands at base of fin and distally, both bands containing few small orange-yellow spots, and with hyaline area densely dotted with melanophores in middle of fin; second dorsal fin translucent, each membrane densely dotted with white, with narrow black margin, and a few oblique longitudinal rows of spots, yellowish brown basally and a little darker distally. Anal fin yellowish brown to about 3/4 of length of rays, becoming slightly darker towards to margin of fin, rest of fin transparent; caudal fin transparent with narrow dark pigment line along upper edge of the fin, lower third of fin yellowish brown, central part of fin with alternating white and orange-yellow spots on rays, rest of fin with white streaks on rays and membranes. Pectoral fins transparent, with a few yellowish brown spots basally. Pelvic fins yellowish brown basally, rest of fin whitish.

Coloration of preserved material ( Figs. 1 B & 1D). Body opaque white (holotype kept long in formalin, now in ethanol) to yellowish (paratype in ethanol), with sparse melanophores. Head retains scattered melanophores on predorsal area, more numerous in paratype. Remainder of head almost without any pigmentation. Iris dark. First dorsal fin with oblique dark band in middle. Second dorsal fin with widely scattered dots and narrow dark upper margin. Anal fin lightly pigmented. Caudal fin transparent. Pectoral fins transparent, few melanophores visible on upper pectoral-fin base in paratype. Pelvic fins transparent with a few melanophores on spines.

Etymology. Named nanus from the Latin meaning "small" or "dwarf", in reference to the species' small size among Coryogalops species.

Distribution and habitat. At present known in the Red Sea only from two localities: Farasan Island, Saudi Arabia and Dahab, Egypt. The holotype was collected on a patch of rubble-sand bottom in a large inner lagoon of main Farasan Island in less than one meter depth. It was found among shells sparsely covering the patch. The paratype was collected also on a patch of rubble-sand bottom at depth of 3 m, and was found inside a shell. More material and data are required to check the relationship of this species to shells and their use as shelters.

Remarks. Coryogalops nanus sp. nov. differs from other species of the genus by a combination of characters and can be easily distinguished by: low pectoral-fin ray count, 12–14 versus 15−23 in all other species; low longitudinal scale series count, 26−29 versus 30−46, except for C. ocheticus which has 26−31 rows; and low count of transverse rows backward, 7−8 versus 9−16 in other species except for C. anomolus with 8−9 rows, and C. ocheticus with 8–10 rows. In addition to these characters, C. nanus sp. nov. differs from C. anomolus in having the pelvic fins united into a pelvic disc, from C. bulejiensis in lacking a supraorbital tentacle, from C. sordidus ( Smith, 1959) in lacking scales in the prepectoral area, and from all other species (except for C. monospilus and C. pseudomonospilus ) in lacking a tentacle or flap on the posterior rim of the anterior nostril.

Coryogalops nanus sp. nov. can be distinguished from other species by its unique coloration: body semitranslucent with white internal spots visible above the anal-fin base and ventrally on caudal peduncle; scattered small spots and speckles on head, body, and prepectoral area, those on predorsal area and a few along the side of the body with tiny black spots; and in coloration of first dorsal fin.

Coryogalops ocheticus is the most similar species, sharing with C. nanus sp. nov. a low longitudinal scale count (26−31), low count of transverse scale rows (8−10), having orange spots on the head and prepectoral area, and having only two upper pectoral-fin rays free of membrane. However, besides the two morphological characters ( C. nanus sp. nov. with lowest pectoral-fin ray count and with no flap on posterior rim of anterior nostril) and details of coloration ( C. nanus sp. nov. has a series of internal white spots along the ventral part of body) it also differs from C. ocheticus by the additional set of characters ( Table 2 ).

Coryogalops nanus sp. nov. is probably a dwarf species, the smallest known in the genus, as both examined specimens are adult males of about 15 mm SL. However, more specimens are needed to confirm the species’ small size.

Figures

FIGURE 1. Coryogalops nanus sp. nov. SMF 35753, holotype, male, 14.7 + 4.1 mm, Red Sea, Saudi Arabia, Farasan Archipelago, Farasan Island: A) freshly collected specimen. B) preserved specimen. PMR VP 3048, paratype, male, 15.2 + 4.3 mm, Red Sea, Egypt, Dahab: C) freshly collected specimen. D) preserved specimen. Photos by S. Traenkner (A), M. Kovačić (B & D), S. V. Bogorodsky (C).

FIGURE 2. Cephalic sensory systems of Coryogalops nanus sp. nov., PMR VP 3048, holotype, male, 15.2 + 4.3 mm. Terminology in text. Drawing by M. Kovačić.

Tables

TABLE 1. Morphometric characters (% SL) of Coryogalops nanus sp. nov.

Specimen sex	SMF 35753 (field number KAU12-102), holotype male	PMR VP3048, paratype male
Standard length (mm) Body depth (at pelvic-fin origin) Body depth (at anal-fin origin)	14.7 18.9 18.7	15.2 17.8 17.8
Body width (at pectoral-fin origin) Head length Snout length	18.7 32.0 7.1	19.7 30.5 6.6
Orbit diameter Upper-jaw length Caudal peduncle depth	10.0 10.3 15.0	9.5 10.2 14.5
Caudal peduncle length Predorsal length Preanal-fin length	21.5 37.8 62.0	22.5 38.8 59.3
Prepelvic length Base of both dorsal fins Longest spine of first dorsal fin	30.1 43.9 13.6	27.1 41.1 14.3
Spine of second dorsal fin Longest dorsal-fin ray Base of anal fin	13.6 13.9 24.0	12.5 14.1 22.7
Anal-fin spine Longest anal-fin ray Caudal-fin length	13.2 14.3 27.9	11.2 13.8 28.3
Pectoral-fin length Pelvic-fin spine length Pelvic-fin (disc) length	25.5 6.9 23.2	24.7 7.4 23.4

TABLE 2. Set of additonal characters to two apomorphies of C. nanus sp. nov. mentioned in text for distinguishing the new species from C. ocheticus.

C. nanus sp. nov.	C. ocheticus
body semi-translucent with scales outlined with white.	body not translucent and scales outlined by brown on upper half of body and by dull orange on lower half
pelvic fins pale	pelvic fins blackish
orange-yellow spots on head sparse, orange-yellow spots scattered on body and predorsal area	many orange spots on head, and no spots on body and predorsal area
first dorsal fin with two broad white bands and hyaline area densely covered with melanophores in the middle of fin	first dorsal fin mostly un-marked, with indistinct oblique pale band
first three dorsal-fin spines equal in length	second to fourth dorsal-fin spines equal in length
body slender, depth at pelvic-fin origin 5.3−5.6 in SL	body moderately robust 3.9−5.3 in SL ( Miller 1978), 5.1−5.3 in examined material
head large, the length 3.1−3.3 in SL	head not large, the length 3.4−4.4 in SL ( Miller 1978), 3.6 in examined material
reduced number of papillae in transverse suborbital rows (e.g. 1: 5 and 5, 2: 3 and 3, 3: 3 and 3, 4: 4 and 2, 5: 3 and 2, 6s: 4 and 2, 6i: 6 and 6, 7: 2 and 1)	many papillae in transverse suborbital rows (e.g 1: 7−8, 2: 5−6, 3: 5−8, 4: 3−8, 5: 4−7, 6: 12−16, 7: 2−6) ( Miller, 1978)
transverse suborbital rows 2 and 3 at the level of other transverse suborbital rows	rows 2 and 3 below the level of other transverse suborbital rows
longitudinal row b short row extending forwards to row 6	longitudinal row b extending forwards to row 5
row 6 extended downwards to row d	row 6 extended downwards bellow row d
longitudinal row m absent	row m present