Minous groeneveldi, Matsunuma & Motomura, 2018

Matsunuma, Mizuki & Motomura, Hiroyuki, 2018, Three new species of the Indo-Pacific stingfish genus Minous (Synanceiidae: Minoinae) with redescriptions of M. trachycephalus (Bleeker 1855) and M. pictus Günther 1880, Zootaxa 4455 (2), pp. 201-257 : 219-225

Minous groeneveldi sp. nov.

New English name: Groeneveld’s Stingfish

Figures 10–12 , 13A–C , 18 , 19A, B , 20F ; Tables 1–6

Minous pictus not of Günther 1880: Gloerfelt-Tarp & Kailola 1984: 110, unnumbered fig. (Bali, Indonesia; short description; specimen: NTM S.11031-002).

? Minous trachycephalus not of Bleeker 1855: Allen et al. 2003: 380, unnumbered fig. (Pacific Ocean; ecological and identification notes).

Holotype. NTM S.11031-002, 77.7 mm SL, Bali Strait, Indonesia, 08°42′S, 115°05′E, 30 m depth, T. Gloerfelt- Tarp , sta. TGT 2621, 18 May 1983.

Diagnosis. A species of Minous distinguished from other congeners by the following combination of characters: 1st dorsal-fin spine much shorter than 2nd dorsal-fin spine, their bases close together; dorsal-fin rays XI, 11, total rays 22; anal-fin rays II, 9, total rays 11; head depth 13.7% of SL; eye moderately low set on head (horizontal line through top of snout bulge level with ventral margin of pupil in 77.7 mm SL-specimen); anterior and posterior lacrimal spines blunt, tips of both spines canted ventrally; body entirely pale pink or yellow with narrow dusky stripe centrally, but without oblique alternating dark and light stripes; inner surface of pectoral fin largely bright yellow (whitish in preserved specimens) basally with dark stripes along rays, distal portion largely yellow (whitish) when fresh; pore above pectoral-fin base associated with short, rounded skin flap.

Description. Pectoral-fin rays 12, lowermost ray free from membrane; pelvic fin rays I, 5. Vertebrae 11 + 15 = 26. Other meristics and morphometrics shown in Tables 1–6. Body oblong, moderately compressed laterally, without scales ( Fig. 11 ). Lateral-line tubes continuous, except for last isolated tube on caudal peduncle; each tube with a pore opening to short skin tube on posterior end, short cirri associated with pore. Single slit-like pore opening above pectoral-fin base behind gill opening, edge with short, rounded, fleshy skin flap.

Head moderately large, exposed bony surface rough with numerous small spines; interorbital space deep, interorbital ridges developed, well separated from each other; occipital pit well developed, very deep. Anterior and posterior lacrimal spines blunt, canted ventrally, posterior spine slightly longer than anterior spine; suborbital ridge with rough bony clusters with numerous small spines; preopercle with 5 spines, uppermost spine behind end of suborbital ridge longest, lowermost 2 spines blunt, plate-like; 3 sensory pores on underside of dentary; small pore on each side of symphysial knob; lateral and ventral surfaces of anterior portion of lower jaw with many cirri or tentacles, 2 relatively long tentacles located between each sensory pore, posterior tentacle below lacrimal spines longer than anterior tentacle, tip of posterior tentacle extending beyond posterior margin of maxilla when laid flat.

Snout blunt; dorsal profile of snout relatively steep, forming angle of ca. 40°to horizontal axis of head and body. Mouth moderately large, slightly oblique, forming angle of ca. 30°to horizontal axis of head and body; posterior margin of maxilla not reaching a vertical through mid-orbit; upper edge of posterior part of maxilla swollen laterally, forming low ridge. Lower jaw tip slightly projected anteriorly when mouth closed. Symphyseal gap separating premaxillary teeth bands very narrow, less than width of each band; both jaws with a band of small, conical teeth, ca. 6 and ca. 5 teeth rows at widest portions of upper and lower jaw, respectively; 2 small elongate small patches of small conical teeth on vomer; palatine teeth absent.

Eye moderately large, with numerous tentacles on dorsal portion, longest tentacle branched, tips extending beyond dorsal contour of orbit. Eye set relatively low on head, dorsal contour of orbit (about one-fourth of orbit) extending beyond a line between snout tip and dorsal-fin origin; horizontal line parallel to head and body axil through top of snout bulge just reaching ventral margin of pupil. Preocular, supraocular and postocular (surrounding orbit) rough, with numerous spines.

Dorsal-fin origin just behind occipital pit, surrounded by parietal spine clefts; 1 st spine relatively short, thin, much shorter than 2nd spine, its length 36 % of 2nd spine length, their bases close together; 3rd spine shorter than 2nd spine, its length 84 % of 2nd spine length; 3rd to 5th spines gradually becoming longer posteriorly, remaining posterior spines subequal in length; membranes in anterior spinous portion well incised, remaining membranes moderately incised; 2nd and 3rd spines associated with many small dermal flaps on both lateral sides. Dorsal contour of soft-rayed portion of dorsal fin rounded, longest soft ray length subequal to 2nd spine length; last soft ray attached to caudal peduncle by broad membrane. Anal-fin origin below 11th dorsal-fin spine base; spines tiny, covered with skin; longest anal-fin soft ray subequal to longest dorsal-fin soft ray in length; last soft ray attached to caudal peduncle by broad membrane. Pectoral fin rounded, moderately large, 6th ray longest, its tip extending far beyond a vertical through anal-fin origin but not reaching end of anal-fin base; lowermost ray long, slightly thickened, free from membrane, its base well separated from base of adjacent membrane-associated ray, its tip extending slightly beyond a vertical through anal-fin origin when depressed. Pelvic-fin origin below 4th dorsal-fin spine base, spine covered with skin, last soft ray attached to abdomen by broad membrane; 4th soft ray longest, its tip just reaching a vertical through anal-fin origin when depressed; end of pelvic-fin base not reaching level of anus. Caudal fin moderately long, posterior margin slightly rounded. All segmented rays in dorsal, anal, pectoral, pelvic and caudal fins unbranched.

Fresh coloration of holotype, based on color photograph of fresh holotype ( Fig. 12 ). Body entirely pale orange, whitish ventrally, a relatively broad black stripe centrally; lateral line tinged with black. Head pale orange, whitish ventrally; both jaws whitish; eye dark orange, pupil black. Dorsal-fin membrane coloration same as body; spines distally tinged with black; poorly defined large black blotch on basal membranes of posterior spinous portion between 7–11th spines, continuous with body stripe ventrally; ventral and posterior portions of soft-rayed portion mostly black with irregularly shaped small pale-orange blotches anteriorly and distally. Anal fin mostly black, dusky orangish basally. Pectoral fin outer surface black, with poorly defined pale orange blotch centrally; lowermost free ray gray, dusky orange distally; inner surface and axil coloration undetermined. Pelvic fin black, whitish anteriorly, with numerous irregularly shaped small white blotches forming somewhat hexagonal pattern. Caudal fin pale orange, dusky dorsally and posteriorly, with numerous small faint white spots scattered on rays; spots on uppermost ray brownish.

Live coloration, based on underwater photographs ( Fig. 13A–C ). Large individual ( Fig. 13A, B ): Overall coloration, including pattern of dark marks, similar to that of holotype. Pectoral fin inner surface black with broad whitish outer margin, membranes of basal portion bright yellow, rays narrowly tinged with black; axil whitish with many small black blotches. Small individual ( Fig. 13C ): Head and body pale yellow, orangish ventrally, with relatively large brown blotch mid-dorsum below posterior potion of dorsal-fin spinous portion, extending onto dorsal fin. Outer surface of pectoral fin pale yellow, dark reddish basally.

Coloration of preserved holotype, based on holotype ( Fig. 11 ). Head and body entirely creamy-white; body with narrow brown stripe centrally, diffuse posteriorly; lateral line with brown tinge. Two poorly defined brown bands below eye; anterior band on sides of snout from anteroventral margin of orbit to lacrimal; posterior band broad, from posteroventral margin of orbit to ventral portion of opercle. Dorsal fin creamy white; large brown blotch on posterior portion of spinous portion, barely continuous with central body stripe; posterior portion of softrayed portion mostly brown with many small creamy-white blotches. Anal fin brown with creamy-white basal portion. Pectoral fin outer surface brown with irregular narrow white band centrally, inner surface brown with broad white dorsal margin, membranes of basal portion pale white, rays narrowly tinged with black ( Fig. 11D ); axil brown with faint white blotches forming somewhat hexagonal pattern. Pelvic fin brown, whitish anteriorly, with numerous small white blotches forming somewhat hexagonal pattern ( Fig. 11E ). Caudal fin entirely pale creamywhite, dusky distally, without distinct markings.

Etymology. The name groeneveldi is proposed in honor of Mr Rokus Groeneveld, who provided us with excellent underwater photographs of the new species.

Distribution. Minous groeneveldi is currently known only from the holotype, collected at a depth of 30 m off Bali, and underwater photographs taken in Lembeh Strait, North Sulawesi, Indonesia ( Figs. 10 , 13A–C ), but may have a wider distribution in the East Indies.

Remarks. The holotype of the species was previously recorded and illustrated (as M. pictus ) in Gloerfelt-Tarp & Kailola (1984).

Identification of sub-adults from underwater photographs. An apparently sub-adult individual (ca. 40–50 mm SL) photographed in Lembeh Strait ( Fig. 13C ) was identical with M. groeneveldi , having blunt anterior and posterior lacrimal spines with ventrally canted tips, a relatively low set eye and dark dorsal coloration, although it

had an otherwise somewhat different body appearance compared with large adults ( Figs. 12 , 13A, B ). In fact, at this growth stage, M. groeneveldi is similar to M. trachycephalus ( Fig. 13D ), having a similar overall body appearance and coloration. However, judging from underwater photographs ( Fig. 13 ), small M. groeneveldi can be distinguished from M. trachycephalus by the largely semi-translucent dorsal-fin membrane in the former (a distinct yellow band in the latter) and a largely yellow dorsum (except for a brown blotch below the posterior portion of the spinous dorsal-fin base) (dorsum lacking a large yellow area in the latter). Although the largely pale pectoral fin outer surface in M. groeneveldi ( Fig. 13C ) may also distinguish that species from M. trachycephalus (outer pectoral fin entirely brown with irregular yellow narrow bands), the former feature was not apparent in large adult M. groeneveldi ( Figs. 12 , 13A, B ). Similarly, the M. trachycephalus individual illustrated by Allen et al. (2003) may have been an example of M. groeneveldi , having largely pale dorsal-fin membranes and dorsum, but specific identification from the photograph was equivocal.

Figures

FIGURE 10. Distributional maps of Minous trachycephalus (purple squares); M. groeneveldi sp. nov. (yellow stars); M. roseus sp. nov. (blue circles); M. andriashevi (gray downward triangles); M. pictus (yellow upward triangles); and M. radiatus sp. nov. (green diamonds). White arrowheads indicate type localities. Black arrowheads indicate photographic records (Lembeh Strait, North Sulawesi, Indonesia).

FIGURE 11. Preserved holotype of Minous groeneveldi sp. nov. (NTM S.11031-002, 77.7 mm SL, Indonesia)—Lateral views (A, B); dorsal view (C);—magnifications of pectoral fin inner surface (right side, reversed) (D) and pelvic fin (E).

FIGURE 12. Fresh holotype of Minous groeneveldi sp. nov. [NTM S.11031-002, 77.7 mm SL, Indonesia (right side, reversed)]. Photo: Thomas Gloerfelt-Tarp.

FIGURE 13. Underwater photographs of Minous groeneveldi sp. nov. (A–C) and M. trachycephalus (D, E) from Lembeh Strait, North Sulawesi, Indonesia. Photos: Rokus Groeneveld.

FIGURE 18. Relationships of (A) head length; (B) snout length; (C) interorbital width at mid-orbit; and (D) 1st dorsal-fin spine length (all as % of standard length) to standard length (mm) in Minous roseus sp. nov. (blue circles), M. groeneveldi sp. nov. (yellow star, holotype), M. trachycephalus (purple squares) and M. pusillus (black crosses). Open arrowhead indicates paralectotype of M. pictus (= M. trachycephalus). Closed arrowheads indicate holotypes of M. roseus and M. trachycephalus, and lectotype of M. pusillus.

FIGURE 19. Relationships of (A) head depth; (B) interorbital width at preocular spine base; and (C) 2nd dorsal-fin spine length (all as % of standard length) to standard length (mm) in Minous roseus sp. nov. (blue circles), M. groeneveldi sp. nov. (yellow star, holotype) and M. trachycephalus (purple squares). Open and closed arrowheads indicate paralectotype of M. pictus (= M. trachycephalus) and holotype of M. roseus, respectively.

FIGURE 20. Lateral view of head (A, C, G) and lacrimal spines (semi-schematic) in Minous groeneveldi sp. nov. (A, B), M. roseus sp. nov. (C–F) and M. trachycephalus (G–K). (A, B) NTM S.11031-002, holotype, 77.7 mm SL, Indonesia; (C, D) CSIRO CA1844, holotype, 72.1 mm SL, Western Australia; (E) CSIRO CA1589, paratype, 53.9 mm SL, Western Australia; (F) NMV A29660-012, paratype, 33.5 mm SL, Western Australia; (G) RMNH.PISC. 5901, holotype, 55.9 mm SL, Indonesia; (H) KAUM–I. 33284, 70.4 mm SL, Thailand (Gulf of Thailand); (I) KAUM–I. 49280, 55.2 mm SL, Malaysia (Borneo); (J) KAUM–I. 33288, 55.7 mm SL, Thailand (Andaman Sea); (K) BMNH 1879.5.14.372, paralectotype of M. pictus, 36.6 mm SL, Arafura Sea. Red dotted lines (in A and C) indicate horizontal line through top of snout bulge. Red and blue arrowheads indicate anterior and posterior lacrimal spines, respectively. Bars indicate 1 mm.