Trichonotus cyclograptus ( Alcock, 1890 )

Katayama, Eri, Motomura, Hiroyuki & Endo, Hiromitsu, 2012, A new species of Trichonotus (Perciformes: Trichonotidae) from Somalia and redescription of Trichonotus cyclograptus (Alcock, 1890) with designation of a lectotype, Zootaxa 3565, pp. 31-43 : 32-33

Trichonotus cyclograptus ( Alcock, 1890)

[New English name: Bengal Sand diver] ( Figures 1–3 , 6 ; Tables 1–2)

Taeniolabrus cyclograptus Alcock, 1890: 430 , fig. 1 (type locality: Ganjam Coast, Bay of Bengal); Alcock, 1898: pl.20, fig. 5 (illustration); Menon & Yazdani, 1968: 146 (note); Menon & Rama-Rao, 1970: 377 (note). Trichonotus cyclograptus: Shimada & Yoshino, 1984: 18 (comparison); Randall & Tarr, 1994: 309 (key); Katayama & Endo, 2010: 1 (comparison).

Lectotype. BMNH 1891.9.2.1, male, 109.7 mm SL, Ganjam Coast, Bay of Bengal, 18–24 m, 2 Sep. 1891.

Paralectotypes. 2 specimens: ZSI F 12932, male, damaged, ZSI F 12935, male, 106.2 mm SL, same data as lectotype.

Diagnosis. Trichonotus cyclograptus is distinguished from other congeners in having the following combination of characters: no elongated dorsal-fin spines in males; dorsal-fin rays IV, 45–46; anal-fin soft rays 37–38; lateral-line scales 57–59; two free dorsal pterygiophores; gill rakers 6+23; body markings in males 12; median predorsal-fin scales 10; interorbital width 43.7% of eye diameter; abdominal scales small.

Description. Data for the lectotype presented first, followed by those for the less damaged of the two paralectotypes (ZSI 12935) in parentheses. Dorsal-fin rays IV, 45 (46); anal-fin rays I, 37 (38); pectoral-fin rays 15 (14); caudal-fin rays 13 (–); lateral-line scales 57 (59); scales above lateral line 4.5 (–); scales below lateral line 5.5 (–); median predorsal-fin scales 9 (damaged); gill rakers on 1st arch 6+23 (–); pseudobranchial filaments 12(–); vertebrae 53 (–).

Proportional measurements are shown in Table 1, the proportional characters being based on BMNH 1891.9.2.1. Body long, slightly cylindrical, compressed posteriorly. Snout long, pointed, its length twice eye diameter. Mouth large, maxilla reaching posteriorly to vertical through anterior rim of pupil; lower jaw extending anteriorly beyond upper jaw tip, bordered along side by uniserial row of 18 short cirri. Opercle just reaching posteriorly to pectoral-fin base. Gill membranes free from isthmus. Gill rakers long, spinous, the longest more-orless subequal to length of longest gill filaments. Tongue narrow, slightly expanded anteriorly, tip rounded. Eye small, slightly oval, 10 hair-like elongated “lashes” on iris flap. Suborbital skin fold slightly covering lower margin of eye, discontinuous at midpoint; with 7 embedded scales adjacent to infraorbital cephalic sensory canal ( Fig. 3 B). Interorbital space narrow, its width equal to 1/3 eye diameter. Nostrils small, closer to snout tip than to anterior margin of eye; anterior nostrils short and tubular; posterior pore-like. Cycloid scales covering body; posterior edge of scales slightly angular. Lateral line along mid-body, each associated scale rhomboid with a posterior notch. Scales on abdomen smaller than those on sides of body, 29 rows anterior to anus. Scales between supratemporal cephalic sensory canal and dorsal-fin origin small, diagonally arrayed, those located posteriorly on pectoral-fin base half the size of body scales. Upper jaw teeth near symphysis large, canine-like, in 4 irregular rows, becoming small, conical and in 3 irregular rows posteriorly. Lower jaw teeth large, in a single row anteriorly, gradually decreasing in size, in 2–3 irregular rows posteriorly. Head of vomer crescentic, palatines narrow with villiform teeth. Dorsal-fin spines flexible, not filamentous; dorsal fin soft rays unbranched except for posteriormost. Dorsal fin high in males, its height equal to twice body depth. Anal-fin spine flexible, shorter than adjacent soft rays; all soft rays branched. Caudal fin rounded in males, uppermost and lowermost rays short, unbranched. Pelvic fin insertion anterior to pectoral-fin base; 4th soft ray unbranched, elongated, extending beyond anus in males; 3rd soft ray short, 2/3 length of 4th ray. First 2 dorsal pterygiophores located between 6th and 7th neural spines; 2 free pterygiophores between 6th and 7th spines. First anal pterygiophore located below 15th vertebra.

Cephalic sensory canal patterns are illustrated in Fig. 3 . Tip of infraorbital canal closely adjacent to supraorbital canal, but separated anterior to eye. Infraorbital canal with 8 pores (2 pairs of 2 pores posteriorly); preopercular canal with 8 pores, the 3th comprising 2 pores; mandibular canal with 3 pores, continuous with preopercular canal.

Color when fresh (from Alcock 1890). Head and body brownish gold. Body with 12 inconspicuous dark bands. Vertical fins translucent, with blue spots arranged in longitudinal rows; 10 rows of 50 spots on dorsal fin, 3 rows of about 40 spots on anal fin.

Color in alcohol ( Fig. 1 ). Ground color of body and head pale brown, dorso-lateral surface of body with 12 brown marks, anterior 5 extended ventrally. Dorsal fin with numerous small white spots, anal fin with three longitudinal rows of small white spots. Three longitudinal rows of small regular dark brown-edged spots on body, the middle row along the lateral-line scales. Snout to occiput with a fine dark network of spots. Head with irregular rows of spots, those on snout to above opercle dark-edged. Ventral surface of lower jaw uniformly pigmented. Pelvic and caudal fins brownish, translucent; tips brownish. Caudal fin with scattered white spots. Female coloring unknown.

Distribution. Known only from sandy bottoms off the Ganjam Coast, Bay of Bengal, at a depth of 18– 23 m.

Remarks. Although the original description of T. cyclograptus was very short, the accompanying illustration clearly depicted the main diagnostic features of the species ( Fig. 2 A). Subsequently, Alcock (1898) included an illustration of T. cyclograptus in a list of fishes collected by R/V Investigator ( Fig. 2 B), apparently based on a different syntype from that figured previously.

Among the eight syntypes indicated in Alcock (1890), four had been deposited in the fish collection of the Zoological Survey of India (ZSI), one being subsequently transferred to the Natural History Museum, London (BMNH). The remaining four specimens have been missing for some years ( Menon & Yazdani 1968; Menon & Rama-Rao 1970; Eschmeyer 2012). During the present investigations, three syntypes were found: BMNH 1891.9.2.1 (formerly ZSI F 12828) (still in good condition), and ZSI F 12932 and ZSI F 12935 (both damaged) ( Fig. 1 ). Although ZSI F 12936 was believed to exist at ZSI ( Eschmeyer 2012), it has recently been confirmed as missing and probably lost (S. Mishra, pers. comm.). Except for the caudal fin shape, the BMNH syntype otherwise agrees with the illustration of T. cyclograptus in Alcock (1890), having similar dorsal- and pelvic-fin shapes, 49 dorsal-fin rays, 13 narrow saddle-like markings on the sides of the body, and three longitudinal rows of small white spots on the anal fin ( Figs. 1 A, 2A). Our examination of BMNH 1891.9.2.1 and ZSI F 12932 revealed that the posterior caudal fin margin of T. cyclograptus was somewhat rounded when expanded, rather than pointed ( Figs. 1 , 2 B). Hence, the diagnostic status of the caudal fin (pointed), as believed by some authors (e.g. Randall & Tarr 1994), is here regarded as erroneous. We designate BMNH 1891.9.2.1, which closely resembles the figures by Alcock (1890 1898), as the lectotype of T. cyclograptus , so as to forestall any further taxonomic problems.

Among the species of Trichonotus lacking elongated dorsal-fin spines, Trichonotus cyclograptus is very similar to T. arabicus , sharing III–IV, 44–46 dorsal-fin rays, 37–39 anal-fin rays, 6–8+20–23 gill rakers, a nonelongated dorsal spine, and dark markings on the body, but differs from the latter in having 12 saddle-like bands on the body (vs. a longitudinal row of 14 dark markings in T. arabicus ), 57–59 lateral-line scales (vs. 55–57), small abdominal scales with 29 pre-anus rows (vs. large, 20–22 rows), and a greater interorbital width (43.7% of eye diameter vs. 28.4−36.7%).

Figures

FIGURE 1. Preserved specimens of Trichonotus cyclograptus. A. BMNH 1891.9. 2.1, lectotype, male, 109.7 mm SL, B. ZSFI 12935, paralectotype, male, 106.2 mm SL, C. ZSFI 12932, paralectotype, male (in pieces).

FIGURE 2. Two illustrations of the syntypes of Trichonotus cyclograptus. A. from Alcock (1890); B. from Alcock (1898).

FIGURE 3. Cephalic sensory pore system in Trichonotus cyclograptus, BMNH 1891.9. 2.1, lectotype, male, 109.7 mm SL. (A) dorsal view, (B) lateral view, (C) ventral view. Bar indicates 5 mm.

FIGURE 6. Distributional records for Trichonotus somaliensis sp. nov. (open stars), T. arabicus (solid circles), T. cyclograptus (solid star).