Malthopsis austrafricana, Ho, Hsuan-Ching, 2013

Ho, Hsuan-Ching, 2013, Two new species of the batfish genus Malthopsis (Lophiiformes: Ogcocephalidae) from the Western Indian Ocean, Zootaxa 3716 (2), pp. 289-300 : 294-299

Malthopsis austrafricana n. sp.

English name: Southern African triangular batfish Figs. 3 A–C, 4, 5A–E; Table 1

Malthopsis lutea (non Alcock, 1891): Smith 1961: 573.

Malthopsis tiarella (non Jordan, 1902): Bradbury 1986: 373.

Holotype. SAIAB 81896 (70.0 mm SL), 25°23’S, 34°29.3’E, off Mozambique, bottom trawl, 311–314 m, 6 Oct. 2007.

Paratypes. 16 specimens, 45.2–84.0 mm SL. MNHN 1986-10–11 (2 specimens, 64.8, 75.1 mm SL), N.o.vauban, 23°36’00”S, 43°31’05”E, Madagascar, 395–410 m, 26 Feb. 1973. MNHN 1986-0019 (1, 84.0), N.o.vauban, 12°43’01”S, 48°15’00”E, Madagascar, 348–360 m, 14 Jul.1971. MNHN 1986-91 (1, 53.9), 12°30’00”S, 48°13’59”E, 410 m, 11 Oct. 1974. MNHN 1986-0124 (1, 65.6), 13°45’07”S, 47°38’02”E, 430–700 m, 28 Feb. 1975. SAIAB 13721 (1, 47.5), 31°59’S, 29°09’E, Coffee Bay lagoon, Eastern Cape, South Africa, 23 Aug. 1973. SAIAB 28477 (2, 45.2, 66.0), S of Maputo, Mozambique, Dec. 1987. SAIAB 48433 (1, 47.3), Port Alfred, Eastern Cape, South Africa, 28 Feb. 1995. SAIAB 81903 (2, 53.4–54.4), 25°5.5’S, 35°18.4’E, off Mozambique, 347–353 m, 7 Oct. 2007. SAIAB 186428 (1, 58.6), 29°10.49’S, 32°5.27’E, off Dokodweni, KwaZulu-Natal, South Africa, 248–251 m, 21 Mar. 2010. SAIAB 188875 (2, 56.0–58.0), northern Madagascar, 8 Aug. 2009. SAIAB 188811 (2, 63.8–67.0), 29°10.32’S, 32°5.37’E, Tugela Deep, KwaZulu-Natal, South Africa, 250 m, 18 Aug. 2010.

Non-types. 22 specimens, 31.5–70.0 mm SL. MNHN 1986-8 (1, 31.5), N.o. Vauban, 12°40’01”S, 48°18’00”E, Madagascar, 185–190 m, 1 Aug. 1973. MNHN 1986-22 (1, 53.5), N.o. Vauban, 12°52’05”S, 48°10’05”E, Madagascar, 400–410 m, 4 Mar. 1971. MNHN 1986-57 (1, 41.4), N.o. Vauban, 12°33’07”S, 48°17’02”E, Madagascar, 355– 265 m, 18 Jan. 1972. MNHN 1986-58 (1, 55.7), N.o. Vauban, 22°21’07”S, 43°04’05”E, Madagascar, 450 m, 27 Nov. 1973. MNHN 1986-79–90 (12, 45.8–70.0), N.o. Vauban, 12°30’00”S, 48°13’59”E, Madagascar, 410 m, 11 Oct. 1974. MNHN 1986-92 –93 (2, 48.3, 51.9), N.o. Vauban, 12°30’00”S, 48°13’59”E, Madagascar, 410 m, 11 Oct. 1974. MNHN 1986-0116 (1, 61.9), N.o. Vauban, 12°52’01”S, 48°10’05”E, Madagascar, 420–428 m, 4 Mar. 1971. MNHN 1988-1573 (1, 34.8), N.o. Vauban, 15°19’59”S, 46°11’02”E, Madagascar, 170–175 m, 19 Jan. 1975. SAIAB 4632 (1, 42.5), 29°51’S, 31°E, off Durban, KwaZulu- Natal, South Africa, no date. SAIAB 28266 (1, 40.0), 33°31’S, 27°06’E, Great Fish River mouth, Eastern Cape, South Africa, 27 Jan. 1988 [dried out].

Diagnosis. A species of Malthopsis distinguished by the following combination of characters: body covered by conical bucklers and numerous prickles; rostrum long (mean 8.3% SL) and stout, pointed, with a broad base, directed forward horizontally; 3 irregular rows of bucklers on top of head; ventral surface of disk densely covered by prickles and small flat bucklers, some slightly larger and denser bucklers on breast than on belly; subopercular buckler blunt, without well-developed spines; orbit small (mean 12.5% SL); both post-subopercular bucklers with small spinelets on the tips; interorbital space broad (mean 8.4% SL), forming a deep groove; OD/RL = 1.1–1.9; OD/IO = 1.3–1.7; anal fin reaches to or beyond the caudal-fin base when depressed.

Description. Body depressed, disk markedly triangular in dorsal view, cranium elevated above rest of disk; tail base narrow; caudal peduncle very strong and broad, semi-cylindrical, flattened ventrally and tapering posteriorly; rostrum pointed, strong, with a broad base, directed forward horizontally ( Figs. 5 A–B), distinctly overhanging illicial cavity and mouth; rostrum long, 9.4% SL (6.0–10.7% SL, mean 8.3% SL), much shorter than orbital diameter; orbit small, 12.1% SL (10.7–14.5% SL, mean 12.5% SL), directed dorsolaterally; no pupillary operculum; interorbital space wide 9.4% SL (7.4 9.7% SL, mean 8.4% SL), forming a deep groove ( Fig. 5 A); frontal ridge slightly convex.

Illicial cavity small, oval, as high as wide; esca a single bulb, bearing 2 small cirri on dorsal margin; mouth small, terminal; small villiform teeth on jaws forming narrow bands, those on fifth ceratobranchial forming 2 large, elongated, adjacent patches; teeth on vomer and palatines in quadrangular patch.

Squamation on dorsal disk well developed, consisting mainly of low, pointed, conical, variable-sized bucklers ( Fig. 5 C), interspaces between large bucklers covered by small bucklers and prickles; bucklers on frontal ridge small and blunt, two enlarged preorbital bucklers which overlap anterior border of orbit, upper buckler larger, fused to base of rostrum, with rostral spine forming a trident; usually 5 smaller, subequal-sized bucklers on supraorbit ( Fig. 5 B); interorbital space densely covered by small bucklers; supraorbital membrane covered with 2 (2–3) rows of small bucklers on upper margin of orbit, naked elsewhere. Dorsal surface of cranium covered by 3 (2–3) regular rows of bucklers, two outer rows with 3 (2–3) large bucklers on each, those on median row smaller, usually with a few smaller ones adjacent ( Fig. 5 A); shoulder with small naked areas, extending to gill openings and base of pectoral elbows; two irregular median rows of large bucklers predorsally, ending before dorsal-fin origin as a rectangular cluster of 5 large bucklers ( Fig. 5 C).

Disk margin with a cluster of suborbital bucklers anteriorly, forming three well-defined rows posteriorly; uppermost row of bucklers elevated, slightly pointed, broad based; middle and lower rows of bucklers depressed, associated with lateral line, apices elevated; on median row directed laterally, on lower row directed ventrally; neuromasts well defined. Subopercular buckler enlarged, extended slightly beyond disk margin laterally; terminating on uppermost and middle rows of disk-margin bucklers; smaller spinelets (variable in size and coverage) at its tip ( Fig. 5 D); two well-defined, post-subopercular bucklers, each bearing small spinelets. Pectoralfin base on rear part of disk; covered dorsally with well-developed conical bucklers; 4 (3–5) fine bucklers over anterior fin ray, naked elsewhere.

Dorsal surface of tail strongly armoured, entirely covered with large, elevated, apically pointed bucklers; a row of 4–5 large dorsolateral bucklers extending from last pair of predorsal bucklers below dorsal fin; a longer, highly irregular, semi-oblique row of slightly smaller bucklers along lateral margin of tail to caudal-fin base; an irregular row of flattened bucklers on dorsal midline before caudal fin; dorsal tail rows uniting to form a single, slightly elevated buckler at its base. Lateral margin of tail with two rows of small, low bucklers associated with lateral line, similar to those of disk margin.

Ventral surface of disk predominantly covered with low, flat bucklers; no apical spines on each buckler; belly densely covered with prickles and small bucklers, some slightly larger and denser on breast than on belly ( Fig. 5 E); rear margin of anus surrounded by 7 (6–7) flat bucklers; a large naked area present outside gill chamber in holotype and some paratypes (smaller naked areas in some paratypes); ventral surface of tail with a regular row of conical bucklers on each side, coalescing to a bulbous buckler at caudal-fin base.

Fins generally naked, without bucklers, sometimes with small bucklers on rays near caudal-fin base; interradials of pectoral fins thin, transparent; dermal cirri short, thin, flap-like, present on disk margin and lateral sides of tail associated with lateral-line neuromasts.

Coloration. When fresh ( Figs. 3 A–B, 4), dorsal surface uniformly yellowish brown in holotype, with some deeper patches or small dots on dorsal surface and lateral sides of disk and tail in paratypes; dorsal surface of pectoral fin pale brownish; dorsal fin coloured as surrounding background; ventral surface uniformly pale; pelvic and anal fins pale; caudal fin pale, with light brownish base, a pale ventral margin and broad brownish band in rear portion; cirri along lateral disk and tail bright white.

When preserved ( Fig. 3 C), dorsal surface uniformly brownish, bucklers pale yellowish to medium brown; no brown patches on dorsal surface of holotype, some paratypes with a small irregular dark brown patch on each shoulder and some paratypes have one additional patch at front margin of gill opening; one paratype with many small spots running from anterior shoulder to gill opening; naked areas on shoulder often paler; a light brown patch on each disk margin and lateral side of tail of holotype; 2–3 patches on each disk margin and lateral side of tail in paratypes; eyelid dark blue; eye black; peritoneum pale with few small scattered dots; dermal cirri white; caudal fin pale with broad band on rear of caudal fin; pectoral fin of holotype pale, with a broad band on outer margin in some paratypes; ventral and anal fins of holotype pale, with black margin in some paratypes.

Distribution. Known from off South Africa (Dokodweni, Port Alfred, Durban, Coffee Bay), Maputo, Mozambique, and Madagascar. Bathymetric range 170–428 m, with a paratype collected from a lagoon, which might be stranded and another paratype collected from a depth between 430– 700 m. This species is likely endemic to the southwestern Indian Ocean.

Size. A medium-sized species, the largest adult to 84.0 mm SL.

Etymology. Named for southern Africa, the area from which the type series was collected.

Remarks. Specimens of Malthopsis austrafricana n. sp. were identified as M. tiarella by Bradbury (in Smith & Heemstra 1986), indicating the similarity of their general appearance. It differs from M. tiarella by having 4–5 dorsal-fin rays (vs. 6–7); a very strong tail (vs. thinner); and relatively strong bucklers on its dorsal surface. It differs from M. kobayashii in the rostral spine directed forward horizontally (vs. directed forward and upward) and a relatively wide interorbital space (7.4–9.7% SL vs. 6.0–7.5% SL); from M. asperata in having lower bucklers (vs. pyramid-like bucklers with spinelets); and from the western Atlantic species, M. gnoma , in lacking gill filaments on the fourth gill arch (vs. filaments present on the fourth gill arch) and in the rostral spine directed forward horizontally (vs. rather than upward).

A specimen collected from New Zealand (NMNZ P. 052283, 72.8 mm SL) is tentatively identified as M. austrafricana . However, more specimens are needed to verify the status of the New Zealand population.

Discussion

Bradbury (in Smith & Heemstra 1986) recorded three species of Malthopsis from South Africa: M. lutea , M. mitrigera and M. tiarella . The presence of M. mitrigera in the WIO is confirmed from specimens taken off South Africa. However, the other two species do not occur in the WIO. Bradbury (op. cit.: 372) mentioned in the key to species that M. lutea and M. tiarella have “ventral surface of disc with scales in form of minute tubercles” (= minute prickles in present study) and “bucklers may be scattered over ventral surface of disc….” Ho & Shao (2010a) reviewed M. lutea and found ventral surface covered with small bucklers and naked elsewhere, which indicates that the account of M. lutea is another species. Also, Bradbury (op. cit.: 373) reported that her specimen of M. tiarella has 4 or 5 dorsal-fin rays, which differs from the count of 6 or 7 rays for M. tiarella given by Jordan (1902) and Nakabo (2002). Examination of specimens deposited at SAIAB revealed that specimens identified as Malthopsis lutea were actually M. gigas and those of M. tiarella are described as M. austrafricana in the present work.

In summary, five species of Malthopsis are now known from the WIO, and the number is lower than I suspect for the area. With two new species described, we may expect more species will be discovered in the future because there are still large area in the WIO without detailed explorations.

Figures

FIGURE 3. Malthopsis austrafricana n. sp., holotype, SAIAB 81896, 70.0 mm SL. A. Dorsal view, fresh condition. B. Ventral view, fresh condition. C. Dorsal view, preserved condition. A, B. Photo by P. C. Heemstra.

FIGURE 5. Close-up view of body portions of Malthopsis austrafricana n. sp., from the holotype. A. Dorsal view of head. B. Lateral view of head. C. Dorsolateral view of dorsal surface between dorsal fin and cranium. D. Dorsal view of right disk. E. Ventral surface of central portion of disk. Anterior to left in Figs. A, D, E. Anterior to right in Figs. B, C. Not to scale.