Parabembras robinsoni Regan, 1921

Kai, Yoshiaki & Fricke, Ronald, 2018, Taxonomic review of the deep water flathead genus Parabembras with description of the new species Parabembrasmultisquamata from the western Pacific Ocean (Teleostei, Parabembridae), ZooKeys 740, pp. 59-76 : 62-65

Parabembras robinsoni Regan, 1921 Figs 1B, 2B

Parabembras robinsoni Regan, 1921: 418, KwaZulu-Natal, South Africa; Barnard 1927: 936; Smith 1949: 377, pl. 97, off Natal, South Africa; Smith 1961: 377, pl. 97, off Natal, South Africa; Smith 1965: 377, pl. 97, off Natal, South Africa; Knapp 1986: 482, pl. 29, fig. 154.1, Durban to southern Mozambique, South Africa; Schneider et al. 2005: 218, listed, Mozambique.

Parabembras curtus (not of Temminck and Schlegel 1843): Gilchrist 1922: 75, South Africa; Ochiai 1976: 105, pl. E. Afr-97, east coast of South Africa.

Parabembras sp.: Everett et al. 2015: 89, listed, Kenya, Tanzania, Mozambique.

Material examined.

BMNH 1921.3.1.19 (holotype of P. robinsoni , photo only), 24-35 km off Umvoti River, KwaZulu-Natal, South Africa [ca. 29°32'S, 31°36'E], depth 120-130 fathoms [219-238 m], R. Robinson, 1921; MCZ 130275, 127.0 mm SL (1), off Mozambique, 25°26'S, 34°19'E, 356 m depth, RS Algoa-014, 21 June 1994 (3D CTs only); NSMT-P 129786-129792, 126.7-176.1 mm SL (9 specimens), east coast of South Africa, 25°21'S, 34°20.5'E 326 m depth, 6 Dec. 1970.

Diagnosis.

Parabembras robinsoni is distinguished from its congeners in having usually 11 spines in the first dorsal fin (vs. 8-9 in P. curta and 9-10 in P. multisquamata ), a distinct symphyseal knob in the lower jaw (vs. symphyseal knob absent in P. curta and P. multisquamata ), two preocular spines (vs. single in P. curta and P. multisquamata ), and single lachrymal spine (two in P. curta and P. multisquamata ).

Description.

Measurements are shown in Table 1. Body cylindrical, posteriorly moderately compressed, completely covered with ctenoid scales. Anterior lachrymal with single robust spine, posterolaterally directed, in some specimens with small additional spine anteriorly; posterior lachrymal without spine. Two preocular spines present. Interorbital region narrow and slightly depressed, with more than 12 small spines, forming a serrated ridge. Single small postocular spine present. Suborbital ridge strongly or moderately developed, with three robust spines, tip of anteriormost spine below center of eye, second below posterior margin of eye; posteriormost below pterotic spine. Parietal spine sharp, posteriorly directed. Three nuchal spines, one each on supratemporal, posttemporal, and supracleithrum, respectively; posttemporal sometimes with additional spine. Pterotic with two sharp spines posteriorly directed. Posterior rim of orbit armed with small spines. Preopercle with single robust spine, posteriorly directed; usually with supplementary spine; ventral margin of preopercle smooth. Opercle with upper and lower spines, slightly directed dorsoposteriorly and posteriorly, respectively. Dermal flaps on head absent, except for flap on anterior nostril. Gill rakers blunt, usually 4-5 on upper limb; 14-16 (modally 15) on lower limb, including single (longest) raker at angle. Lateral line running parallel to dorsal contour of body, extending beyond caudal-fin base; 38-41 (modally 39) pored lateral-line scales on body and 2-3 on caudal fin, each with single, robust tube.

Mouth large, slightly oblique; maxilla reaching level of anterior rim of pupil; posterior margin of maxilla weakly notched. Upper half of maxilla fitting within groove below suborbital ridge. Lower jaw with distinct symphyseal knob. Upper and lower jaws with villiform teeth in a band; vomer V-shaped with villiform teeth; tooth band on palatine narrow.

First dorsal fin originating above level of pectoral-fin base, usually with eleven spines (in some specimens ten), gradually increasing in length to fifth spine. Last spine of first dorsal fin separated from penultimate spine without membrane, positioned midway between penultimate spine of first dorsal fin and insertion of second dorsal fin. Second dorsal fin with one spine and 8-9 soft rays; first soft ray slightly longer than spine. Second dorsal and anal fins directly opposite each other, nearly equal in length and height. Caudal fin rounded. Pectoral fin usually with 19-21 rays (modally 20), lower 4-7 rays unbranched; its rounded upper half somewhat longer than lower half, slightly extending beyond level of anus.

Coloration. In fresh condition, head and body reddish orange, white ventrally; fins red, interradial membranes pale red; distal margins of dorsal and anal fins dark red; posterior half of caudal fin dark red [based on pl. E. Afr-97 of Ochiai (1976)]. In preserved condition, head and body dark brown; fins pale gray; distal margin of second dorsal, anal and caudal fins dark brown.

Geographical distribution.

Western Indian Ocean, from Durban to at least southern Mozambique, along the east coast of South Africa at depths of 200-600 m ( Knapp 1986). According to Everett et al. (2015), the species may be distributed along the East African coast north to Kenya; however, these records need confirmation.

Remarks.

Parabembras robinsoni was originally described by Regan (1921), characterized as having 10 spines in the first and one spine and nine soft-rays in the second dorsal fin. However, the last spine of the first dorsal fin, which is positioned between the penultimate ray of the first dorsal fin and the insertion of the second dorsal fin, is present in the holotype (BMNH 1921.3.1.19), which has eleven dorsal-fin spines, a distinct symphyseal knob in the lower jaw and a single lachrymal spine; hence, the present specimens are identified as P. robinsoni .

Barnard (1927) and Smith (1949, 1961, 1985) reported P. robinsoni from off the coast of KwaZulu-Natal, South Africa as having ten or eleven spines in the first dorsal fin. The short description by Knapp (1986) also characterized P. robinsoni as having ten or eleven spines in the first dorsal fin and a symphyseal knob in the lower jaw. These characters agree well with the present specimens of P. robinsoni . In contrast, Gilchrist (1922) described P. curta from South Africa and considered P. robinsoni as a junior synonym of P. curta . However, he described the species as having two preocular spines, agreeing with the present specimens of P. robinsoni , but not with P. curta . Similarly, Ochiai (1976) described P. curta from the east coast of South Africa. His photograph clearly shows P. robinsoni , judging by the presence of a distinct symphyseal knob in the lower jaw. Ochiai assumed that P. curta was widely distributed in the Indo-West Pacific, but apparently he confused P. curta and P. robinsoni . Probably due to this report, some subsequent authors mistakenly reported an occurrence of P. curta in the Indian Ocean (e.g., Nakabo 2000, 2002; Yamada et al. 2007).