Saccogaster maculata Alcock, 1889

Nielsen, Jørgen G., Schwarzhans, Werner & Cohen, Daniel M., 2012, Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus, Zootaxa 3579, pp. 1-36 : 14-16

Saccogaster maculata Alcock, 1889

Figs. 9 , 10 , 25 , Table 1 , 2, 5

Saccogaster maculatus Alcock 1889: 389 (type locality: Bay of Bengal).

Saccogaster maculata: Alcock 1891: 226 , fig.; Wood-Mason & Alcock 1891: 30, pl. 7, fig. 3.; Alcock & McArdle 1900: pl. 29, figs. 2 and 2a (intromittent organ); Cohen & Nielsen 1972: 448, fig. 2; Cohen 1987: 1; Nielsen et al. 1999: 109.

Saccogaster maculatus: Menon & Yazdani 1968: 150 (types in ZSI).

Diplacanthopoma (Saccogaster) maculatum: Alcock 1899: 102 .

Material examined (5 specimens and radiograph of syntype (ZSI 11673), 75–87 mm SL). ZSI 13527, female, 81 mm SL and ZSI 13528, female, 75 mm SL, Bay of Bengal, R/V Investigator, bottom trawl, 265– 458 m. ZSI 13045, male, 77 mm SL, Bay of Bengal, R/V Investigator, bottom trawl, 439 m. IOM no cat. no., male, 87 mm SL, Bay of Bengal, 16°56’08’’N, 83°13’04’’E, R/V Vityaz, cr. 33, st. 4929, bottom trawl, 600 m, 1 Jan. 1961. IOM, no cat. no., 72 mm SL, Gulf of Aden, 10°32’12’’N, 49°22’12’’E, R/V Dmitry Stefanov, cr. 5, st. 98, bottom trawl, 450– 445 m, 6 Dec. 1989.

Remarks on material: It was not possible to borrow any of the five specimens from ZSI for this revision and the IOM specimens seem lost so information about S. maculata is based on Cohen & Nielsen (1972: 448–451). Consequently, our information on ethmoid and frontal spines is not based on direct observation, but from available radiographs.

Diagnosis. Saccogaster maculata differs from all other Saccogaster species by the following combination of characters: Distinct pair of (probably) free spines on frontal plate above and behind eyes, strong ethmoidal spine in front of eyes; scales present on sides of body but not on predorsal; some specimens with ventral arm of opercle terminating in a short spine; opercular spine free and with one prong; presence of 2 posterior infraorbital pores, 1 supraorbital pore at upper angle of gill opening and 1 posterior mandibular behind maxillary; anterior gill arch with three long rakers about half length of longest filaments; elongate pectoral peduncle; palatines with several tooth rows; precaudal vertebrae 12–13 and total vertebrae 53– 55; fin rays in dorsal 83–85, anal 53–56 and pectoral 17–18.

Similarity. Saccogaster maculata is most similar to S. staigeri as both are scaled, have gill filaments 1–2 times length of developed rakers and fangs on dentigerous bones. They differ by S. maculata having palatines with several tooth rows (vs. single tooth row) and opercular spine free (vs. hidden). Also S. maculata has posterior infraorbital, supraorbital and posterior mandibular pores, which are all missing in S. staigeri .

Description (from Cohen & Nielsen 1972: 449) The principal meristic and morphometric characters are shown in Table 5 . Head and body elongate and compressed with tapering tail and blunt snout. Skin thin and transparent. Scales absent on predorsal and in a band along bases of dorsal and anal fins except posteriorly, where entire body is scaled. Anteriorly scales widely scattered, posteriorly scales imbricate. The scale pattern in Alcock and McArdle (1900, pl. 29, fig. 2) is inaccurate. Lateral line ( Fig. 9 ) in two non-overlapping sections; anterior, dorsal part with about 12 small papillae extending from upper angle of opercle to about anus; posterior, median part with 8–10 small papillae ending somewhat anterior to base of caudal fin. Dorsal fin origin above pectoral peduncle and anal fin origin well behind midpoint of fish. Pectoral fin extending to more than half the distance from upper angle of peduncle to anal fin; peduncle longer than broad and free of body. Snout depressed and rounded. Small, darkly pigmented papillae and dermal fringes sparsely distributed on snout and a few on posterior part of head. Posterior tip of opercle ends in blunt spine. In some specimens ventral arm of opercle ends in a short spine. Upper jaw ends well behind eyes with posterior part vertically expanded. Anterior gill arch ( Fig. 10 B) with 3–4 spiny knobs on upper branch, one developed raker in angle and lower branch with two developed rakers with a knob in between followed by 12 spiny knobs. Gill filaments 2–3 times length of developed rakers. Two pseudobranchial filaments. Intromittent organ a thick, fleshy, posteriorly-directed stalk with two prominent lobes on tip from which a penis protrudes. Paired testes of “Vityaz” specimen not notably enlarged; a histological section shows spermatozoa arranged in spermatophores.

Axial skeleton (from radiographs): Number of precaudal vertebrae 13. Anterior neural spine considerably shorter than second spine. Neural spines on precaudal vertebrae 2–5 with pointed tips and decreasing in length, spines 6–9 with blunt tips and remaining neural and haemal spines with pointed tips. Parapophyses on vertebrae 7–13. Ribs difficult to observe.

Dentition: Palatines with sharp, pointed teeth in a narrow band several teeth wide. Vomer boomerang-shaped with sharp, pointed teeth. Premaxillaries with band of granular teeth, but near symphysis an inner row of 7–9 elongate, needlelike teeth. Dentaries with a band of granular teeth and an inner row of about 15 pointed teeth.

Head pores (from Cohen & Nielsen 1972: 449): 1 supraorbital pore at tip of snout and 1 at upper angle of gill opening, 3 anterior infraorbital pores below and in front of eye and 2 posterior infraorbital pores below and behind eyes, 2–3 anterior mandibular pore at tip of jaw, 1 posterior mandibular pore behind posterior end of maxillary.

Head morphology from radiograph ( Fig. 10 A): Pair of forward directed strong spines, probably visible, on frontal above and behind eyes, strong upward directed median ethmoidal spine in front of eyes and blunt subdermal spine above eyes. The surface of the frontal plate behind the frontal spines appears to be roughly textured.

Otolith: No data available.

Coloration: Except for dusky pigmentation on snout preserved specimens are without color patterns.

Biology and distribution ( Fig. 25 ). A viviparous species caught in bottom fishing gear on the upper continental slope at depths between 265 and 600 m. Six specimens were caught in the Gulf of Bengal and one in the Gulf of Aden.

*Dorsal fin, anal fin and vertebral counts from only two specimens

Figures

FIGURE 9. Saccogaster maculata, IOM, SL 87 mm (from Cohen & Nielsen 1972).

FIGURE 10. Saccogaster maculata, IOM, SL 87 mm: A—Lateral radiograph of head. B—Anterior right gill arch (from Cohen & Nielsen 1972).

FIGURE 25. Geographic distribution of Hastatobythites and Saccogaster in the Indo-West Pacific. Each marking may represent more than one locality.

Tables

TABLE 5. Meristic and morphometric characters of Saccogaster maculata, S. nikoliviae and S. parva.

	S. maculata 4 specimens*	S. nikoliviae 3 specimens HT 2 PT	S. parva HT ZMH 25268
Standard length	75–87	69 50–57	58
Meristic characters
Dorsal fin rays	83–85	80 82–84	91
Caudal fin rays	no data	10 10	12
Anal fin rays	53–56	51 48–52	64
Pectoral fin rays Pseudobranch. fil.	17(17.3)18	17 17–18 2 2	14 2
Precaudal vertebrae	12–13	13 12	16
Total vertebrae Long rakers on anterior gill arch	53–55 3	53 52–53 3 3	54 5–6
Ant. dorsal ray above vertebra no.	6–7	7 6–7	8
Ant. anal ray below dorsal fin ray no.	32–33	34 33–39	30
Ant. anal ray below vertebra no.	21	23 23–24	23
Morphometric characters in % SL
Head length Head width	29.0(30.3)33.0	26.5 27.0–28.5 14.0 11.0–13.0	25.5 13.0
Depth origin anal fin	13.5	13.5 11.0	13.5
Body width		5.2 4.0–4.2	6.4
Upper jaw	13.5(14.2)14.5	15.0 15.0	12.5
Posterior maxil. height	4.8–5.9	5.4 5.1–5.4	4.6
Diameter of orbit Interorbital width Postorbital length	2.4(2.9)–3.1 3.9(4.4)–4.8	2.4 2.4 2.9 2.5–2.6 19.0 19.5–21.0	3.6 6.2 18.5
Preanal length	59(60.9)64	61 57–60	58
Predorsal length	30.5(33.1)36.0	32.5 31.0–32.5	35.0
Base of pelvic fin to anal fin origin		40.5 37.5–41.0	43.5
Pectoral fin length Pelvic length	12.0(12.8)14.0 9.2(10.6)12.0	15.0 16.0–19.0 14.5 14.0–15.0	17.0 9.8