Schismatogobius risdawatiae, Keith & Lord & Darhuddin & Limmon & Sukmono & Hadiaty & Hubert, 2017

Keith, Philippe, Lord, Clara, DarHuddin, Hadi, Limmon, Gino, Sukmono, Tedjo, Hadiaty, Renny K. & Hubert, Nicolas, 2017, Schismatogobius (Gobiidae) from Indonesia, with description of four new species, Cybium 41 (2), pp. 195-211 : 205-206

Schismatogobius risdawatiae , n. sp. Keith, Darhuddin, Sukmono & Hubert

( Figs 1-2 ; 4 ; 6 ; Tabs I-III)

Material examined. – Nine specimens from Sumatra with a size range of 25.1-30.2 mm SL .

Holotype. – MZB 23800, male (27 mm SL); Padang , Air Terjun Lubuk Hitam, West Sumatra, Indonesia, 1 May 2016, coll. Hubert et al.; BIF 6032.

Paratypes. – MZB 23801, 5 females (25.1-26.8 mm SL); same data as holotype; BIF 6033, 6035 to 6038. MNHN 2016-0309, 1 male, 1 female (27-30.2 mm SL); same data as holotype; BIF 6034, 6039. MNHN 2016-0621, 1 female (23.5 mm SL); Sumatra, 2016, coll. Negrini; tag 12944. Diagnosis

Usually 16 pectoral rays; pectoral fins with a broad dorsal black band. Membrane in first dorsal fin posterior to spine 6 partly connected to base of spine of second dorsal fin in male and not in female. Ventral surface of head in male brownish, frenum slightly pigmented. Ventral surface of head in female whitish with a blackish border and a white mentum; frenum and pelvic disk whitish. A single mitochondrial lineage (BOLD:ADF3588).

Description

A medium sized Schismatogobius (average adult size 27 mm SL). Body naked, slender, almost circular in cross-section. Head rounded, snout rather pointed. Mouth oblique, lower lip more prominent. Jaw lengths in male much great- er than in females; 55.6-63.1% in male (in HL), 27.4-33% in females. Lower jaw reaching a vertical of 1/3 to 1/ 2 in female and exceeding (for 1/4 of eye diameter) a vertical of posterior part of the eye in male. Eyes high on head, close together with interorbital width about a quarter to one third of the eye diameter. Anterior nostril short and tube-like.

Dorsal fins VI-I,9, membrane of first dorsal fin posterior to spine 6 partly connected to base of spine of second dorsal fin in male and not in female. D1 with all spines about equal in length. Anal fin I,9, origin directly opposite to second dorsal fin origin. Caudal fin with 11-12 branched rays, posterior margin rounded. Pectoral fins oblong with posterior margin pointed and 15(2)-16(7) rays (Tab. II), ventralmost ray unbranched. Pelvic fins always I,5, with both fins joined together their entire length between rays 5, forming strong cup-like disc; a well developed frenum between spines slightly lobed; fin not extending beyond anus. Morphomeristics data given in table III.

Tongue bilobed. Teeth in upper jaw (11-22) usually in two or three rows, teeth conical and slightly recurved. Teeth in lower jaw (6-14) in one or two rows of teeth anteriorly and single row laterally, all teeth conical with outer row teeth only slightly enlarged and somewhat recurved.

Cephalic sensory pore system generally with pores B, D and F; pore D singular with other pores paired. Anterior interorbital extension of anterior oculoscapular canal with double terminal pores B slightly posterior to posterior nostril. D pore at rear of intertobital. Posterior extension of anterior oculoscapular canal terminating laterally on each side of head at pore F, just behind posterior edge of eye. Many specimens lacking the preopercular canal and associated pores N and O, while some individuals also lack the posterior section of the oculoscapular canal and its associated pores K and L. Cutaneous sensory papillae not well developed but similar to pattern described by Akihito et al. (1988).

Sexual dimorphism fairly well developed with male having jaws longer than female. Urogenital papilla broadly rounded in females and slightly triangular in male.

Colour in preservation

Usually three vertical black bands in dorsal view; first band below first dorsal fin, second below second dorsal fin and third one at hypural crease. These lateral black body markings alternate with 3 vertical white to grey stripes. Head dusky grey. Ventral surface of head in male brownish, frenum slightly pigmented. Ventral surface of head in female whitish with a blackish border and a white mentum; frenum and pelvic disk whitish ( Fig. 2B ). First dorsal fin with two horizontal black bands. Second dorsal fin mostly cream with horizontal rows of black spots. Caudal fin black and white, with black spot at centre of hypural crease and two white spots posteriorly. Anal fin mostly cream. Pectoral fins with a large dorsal and distal black band; a dark blotch present dorsoposteriorly.

Colour in life ( Fig. 6 )

Male: Usually three vertical black bands in dorsal view; first band below first dorsal fin, second below second dorsal fin and third one at hypural crease. Body red-orange between the black bands; shades of bright electric blue at the border of the black bands. Head and cheeks mottled with brown and orange spots and markings. First dorsal fin translucent at the base, with a superposition of a longitudinal black band and a distal longitudinal orange band. Second dorsal fin translucent with a series of black spots on each ray. Caudal fin black with two median white spots dorsally and ventrally. Pectoral fins orange at the base; median black spot on the dorsal half of the fin, splitting into three vertical bands ventrally; distal margin translucent. Inside of the mouth bright orange. Female: Usually three vertical black bands in dorsal view; first band below first dorsal fin, second below second dorsal fin and third one at hypural crease. Body red between the black bands; shades of bright electric blue at the border of the black bands. Head and nape mottled with brown and orange spots and markings. Cheeks blackish. First and second dorsal fins translucent with black spots along the rays. Caudal fin black with two median white spots dorsally and ventrally. Pectoral fins brownish at the base; median black spot on the dorsal half of the fin, splitting into two vertical bands ventrally; distal margin translucent. Caudal and pectoral fins translucent. Belly brownish-beige. Ventral surface of head dusky grey. Inside of mouth grey.

Figures

Figure 1. – A: Most likely ML tree inferred using the TrN+I model (-lnL = 2888.77, I = 0.655, f(A) = 0.23025, f(C) = 0.31193, f(G) = 0.17856, f(T) = 0.2926, AC =AT = CG = GT = 1.0; AG = 13.12; CT = 6.72). BP are given above each branches. B: Distribution of TrN+I genetic distance within and among species.

Figure 2. – Schematic drawings of the ventral surface of head of Schismatogobius species from Indonesia. A: 14-15 pectoral rays; B: 15-16 pectoral rays; C: 16-17 pectoral rays.

Figure 4. – Distribution area of Schismatogobius species from Indonesia.

Figure 6. – A: Schismatogobius ris- dawatiae n. sp., male, paratype in MNHN 2016-0309, BIF 6039 (Photo N. Hubert). B: Schismatogobius risda- watiae n. sp., female, paratype in MZB 23801, BIF 6035 (Photo N. Hubert).