Schismatogobius arscuttoli, 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 : 207-208

Schismatogobius arscuttoli , n. sp. Keith, Lord & Hubert

( Figs 1-2 ; 4 ; 7 ; Tabs I-III)

Material examined. – Ten specimens from Sumatra with a size range of 26.7-32.7 mm SL.

Holotype. – MNHN 2016-0306, male (28.5 mm SL); Sumatra, Indonesia, 2016, coll. Negrini.

Paratypes. – MZB 23802, 1 female (30.3 mm SL); Lampung Barat , Way Pamerihan, Sumatra, Indonesia, 24 Oct. 2005, coll. Page et al. UF 162774, 2 females (26.7-28.4 mm SL); Lampung County , Way Ngarip, Sumatra, Indonesia, 25 Oct. 2005, coll. Page et al. MNHN 2016-0308, 1 female (32 mm SL); Way Cangup at research station, Bukit Barisan Selatan National Park, Sumatra, Indonesia, 22 Oct. 2005, coll. Page et al. UF 162772, 1 male, 2 females (28-28.8 mm SL); Lampung Barat , Way Pamerihan, Sumatra, Indonesia, 24 Oct. 2005, coll. Page et al. MNHN 2016-0620, 1 female (30.5 mm SL); Lampung Barat , Way Pamerihan, Sumatra, Indonesia, 24 Oct. 2005, coll. Page et al. QM I 38570, 1 male (32.7 mm SL), North Sumatra, Indonesia, 15 Jul. 2003, coll. Smith.

Diagnosis

Usually 16 pectoral rays; pectoral fins banded with rows of dark spots. Membrane in first dorsal fin posterior to spine 6 connected to base of spine of second dorsal fin. Ventral surface of head in male whitish with a blackish bor- der, black mentum and isthmus; frenum slightly pigmented. Ventral surface of head in female whitish with a blackish border, sometimes with a white mentum; frenum and pelvic disk generally whitish. A single mitochondrial lineage (BOLD:ADG5049).

Description

A medium sized Schismatogobius (average adult size 28 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 greater than in females; 56.6-69.6% in male (in HL), 36.5-41.8% in females. Lower jaw reaching a vertical of 1/ 2 in female and exceeding (for 1/3 to 1/2 of eye diameter) a vertical of posterior part of the eye in male. Eyes high on head, close together with interorbital width about 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 connected to base of spine of second dorsal fin. D1 with all spines about equal in length. Anal fin I,9, origin directly opposite to second dorsal fin origin. Caudal fin usually with 11 branched rays, posterior margin rounded. Pectoral fins oblong with posterior margin rounded and usually 16 rays (Tab. II), 3 specimens with 16 rays on one pectoral fin and 17 on the other; 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, fin not extending beyond anus. Morphomeristics data given in table III.

Tongue bilobed. Teeth in upper jaw (22-25) usually in two or three rows, teeth conical and slightly recurved. Teeth in lower jaw (9-15) in 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 always with pores B, D, F, K, L, N and O, pore D singular with all other pores paired; oculoscapular canal absent between pores F and K. Anterior interorbital extension of anterior oculoscapular canal with double terminal pores B slightly posterior to posterior nostril. D pore at rear of intertorbital. Posterior extension of anterior oculoscapular canal terminating laterally on each side of head at pore F, just behind posterior edge of eye. Posterior oculoscapular canal with 2 terminal pores, K and L; preopercular canal with 2 pores, N and O. 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 ( Fig. 7A )

Usually four vertical black bands in dorsal view; first band below first dorsal fin, second and third bands below second dorsal fin and fourth band at hypural crease. These lateral body black markings alternate with 3 vertical brown stripes. Head dusky grey. Ventral surface of head in male whitish with a blackish border, black mentum and isthmus; frenum slightly pigmented. Ventral surface of head in female whitish with a blackish border, sometimes with a white mentum; frenum and pelvic disk whitish ( Fig. 2C ).

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 banded with rows of dark spots; no dark blotch present dorsoposteriorly.

Colour in life ( Fig. 7B )

Female (no live male observed): Usually four vertical black bands in dorsal view; first band below first dorsal fin, second and third bands below second dorsal fin and fourth band at hypural crease. Colour of body between black bands rather grey; pink between the two posterior bands. Entire dorsal part of the body, from nape to hypural base, punctuated with bright electric blue spots. Lower half of body marbled with black, white and pinkish markings. Belly and ventral surface of head dusky. First and second dorsal fins with a few black spots evenly distributed on each ray. Pectoral fins banded with rows of dark spots; no dark blotch present dorsoposteriorly. Caudal fin translucent, with a black hypural base and two median vertical rows of black spots. 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 7. – A: Schismatogobius arscuttoli n. sp., male, holotype MNHN 2016-0306 (Photo P. Keith). B: Schismatogobius arscuttoli n. sp., female (Photo P. Keith).