Parabothus rotundifrons, Voronina & Pruvost & Causse, 2016

Voronina, Elena, Pruvost, Patrice & Causse, Romain, 2016, Parabothus rotundifrons (Pleuronectiformes: Bothidae), a new bothid flatfish from Saya de Malha Bank (Indian Ocean), Cybium 40 (4), pp. 275-280 : 275-278

Parabothus rotundifrons new species

( Fig. 1 , Tabs I-II)

Engyprosopon sp. : Foroshchuk, 1990: 5 (counts, mor-

phometry)

Comparative material

Parabothus taiwanensis Amaoka & Shen, 1993 . – MNHN 2012-0634 , 8 specimens (4 females 92.3-108.2 mm SL, 4 males 73.1-99.1 mm SL) , R / V Alis, Santo 06 cruise, station at 64, 15°66’S, 167°032’E, depth 249-252 m, West of Malo Island , Vanuatu, 4 Oct. 2006 ; MNHN 2012-0633 , male 81.0 mm SL , R / V Alis, Santo 06 cruise, station at 13, 15°46’S, 167°26’E, Palikulo Bay , Aese Island, Vanuatu, depth 146-153 m, 19 Sep. 2006 ; MNHN 2012-0638 , 5 spms (3 males 78.0- 89.4 mm SL, 2 juv. 65.3 and 67.2 mm SL) , R / V Alis, Santo 06 cruise, station at 05, 15°67’S, 167°06’E, depth 114-132 m, North-West of Malo Island , Vanuatu, 15 Sep. 2006 ; MNHN 2013-0329 6 spms (3 females 110.4-112.3 mm SL, 3 males 95.9-108.5 mm SL) and ZIN 55965 (female 109.8 mm SL, male 95.4 mm SL) , R / V Alis, Santo 06 cruise, station at 33, 15°35’ S, 167°17’E, depth 184-238 m, South Tutuba Island , Vanuatu, 26 Sep. 2006 .

Parabothus budkeri (Chabanaud, 1943) . – MNHN 1942- 0031 (holotype, 84 mm SL) 27°16’N, 33°46’E, 516 fathom depth (circa 943.6 m depth), north of Shaab Abu Sadaf on Gohar Bank , Hurghada, Red Sea, Budker collector, 21 Dec. 1938; MNHN 1942- 0032 (paratype, 119 mm SL) and MNHN 1942-0033 (paratype, 50 mm SL), same collection data as MNHN 1942-0031.

Material examined

Four males and two females collected from Saya de Malha Bank (Indian Ocean) with a size range of 73.0- 108.0 mm SL .

Holotype. – ZIN 49152 , male 108.0 mm SL, Saya de Malha Bank , 11°26’S, 60°58’E, 178 m, trawl 81, 20 Apr. 1978, El’sk ( USSR), ninth cruise ( Fig. 2 ).

Paratypes. – ZIN 49153 , female 90.0 mm SL, male 95.0 mm SL, Saya de Malha Bank , 11°42’S, 62°01’E, 235- 250 m, El’sk, eighth cruise, trawl 109, 07 Sep. 1977 ; ZIN 49154 , male 73.0 mm SL, Saya de Malha Bank , 11°10’S, 62°11’E, 230-232 m, El’sk, eighth cruise, trawl 125, 12 Nov. 1977 ; ZIN 49155 , male 97.0 mm SL, female 78.2 mm SL, Saya de Malha Bank , 11°13’S, 62°10’E, 225 m, El’sk, eighth cruise, trawl 135, 14 Nov. 1977 .

Diagnosis

A species of Parabothus with a narrow and concave interorbital space; no obvious sexual dimorphism; steep dorsal profile of the head with slight notch; 8-9 non-serrate gill rakers on the low limb of the first arch; small number of scales in lateral line (48-58); small knob on snout tip and on mandibular symphysis in both sexes; biserial teeth on upper jaw.

Description

Data for the holotype are given first, followed in brackets by the ranges for paratypes and mean for the holotype and paratypes. Morphometrics in SL, in head length and counts are shown in table I.

Dorsal fin rays 97 (92-99, 95.7); anal fin rays 73 (72- 78, 74.3); pectoral fin rays 12 (11-13, 11.8) on ocular side, 9 (9-10, 9.3) on blind side; scales in lateral line 58 (48-58, 52.5); gill rakers 0+9 (0 + 8-9, 8.8); vertebrae 10+29 (10 + 29-30, 29.3).

Percent of SL: head length 22.58 (21.89-22.60, 22.26); body depth 45.53 (42.27-45.89, 44.53); snout length 4.61 (4.11-4.63, 4.43); upper eye diameter 7.74 (7.74-8.89, 8.29); lower eye diameter 7.19 (6.85-8.95, 7.82); interorbital width 1.6 (1.02-1.79, 1.46); length of ocular-side upper jaw 6.45 (6.45-8.11, 7.58); length of blind-side upper jaw 7.19 (7.19- 8.18, 7.61); length of ocular-side lower jaw 9.77 (9.77-10.53, 10.29); length of blind-side lower jaw 10.41 (10.41-11.51, 11.01); depth of caudal peduncle 11.98 (10.68-11.98, 11.13); length of ocular-side pectoral fin 12.63 (12.63-15.07, 13.72); length of blind-side pectoral fin 7.74 (6.67-8.11, 7.43); length of ocular-side pelvic fin 6.27 (6.27-8.95, 7.94); length of blind-side pelvic fin 6.64 (6.64-9.18, 7.88); length of base of ocular side pelvic fin 8.48 (6.89-8.95, 7.89); length of base of blind side pelvic fin 4.33 (2.78-4.66, 3.56); length of longest dorsal fin ray 12.63 (11.13-14.21, 12.53); length of longest anal fin ray 11.34 (11.05-15.07, 12.61); length of midcaudal fin ray 18.99 (16.49-21.10, 19.02).

Body elliptical, deepest at about anterior 1/3 of body, its depth nearly half of body length. Caudal peduncle depth about 1/4 of body depth. Head small, its length about 1/4 of SL; dorsal profile steep, with a slight notch anterior to the interorbital area ( Fig. 3A ). Snout short, not prominent, shorter than eye diameter. Blunt rostral knob on ocular side of tip of snout. Eyes large, about equal to upper jaw length, lower eye slightly anterior to upper eye. Interorbital region moderately broad, deeply concave, without orbital spine. Nostrils on ocular side between rostral knob and upper margin of orbital ridge of lower eye; anterior nostril tubular with a posterior flap, posterior one not tubular, without flap; nostrils on blind side just below origin of dorsal fin, similar in shape but smaller than those on ocular side.

Mouth of moderate size, maxilla extending below anterior part of lower eye; prominent ventrally-directed knob on mandibular symphysis in males and females. Dentition about equally developed on both sides; teeth on upper jaw biserial, those of outer row stronger and more widely spaced than those of inner row, sometimes set irregularly; inner-row teeth close, regularly spaced; teeth on lower jaw uniserial, nearly equal in size and spacing to inner-row teeth on upper jaw. Tip of vomer not projecting far into mouth cavity. Scales large, deciduous, with short ctenii on ocular side, cycloid on blind side ( Fig. 4A ). Interorbital region scaled, tips of both jaws and snout naked on ocular side. Lateral line curved anteriorly on ocular side, absent on blind side. Gill rakers on first arch rather long and slender, not serrate, absent on upper limb ( Fig. 4B ).

Dorsal fin origin on blind side, anterior to upper margin of lower eye, its height about half of head length. Anal fin origin below highest point of gill opening, it is similar to dorsal fin in shape. Bases of the membrane of the dorsal and anal fins perforated. Pectoral fin on both sides short, that on ocular side slightly longer than lower jaw length, that on blind side is half of that on ocular side.

Pelvic fin on ocular side originating at tip of isthmus, below posterior margin of lower eye; fourth ray of pelvic fin ocular side opposite first ray on blind side. Caudal fin pointed, two upper- and lowermost rays simple, other rays branched.

Vent opening on blind side, immediately anterior to origin of anal fin. Urogenital papilla on ocular side.

Colour of preserved specimens

Body with scales greyish brown, pale purple when scales are removed; no distinct colour pattern; body on blind side yellowish white. All fins uniformly greyish brown without any noticeable spots or blotches.

Figures

Figure 1. – Parabothus rotundifrons sp. nov. holotype, ZIN 49152, male, 108.5 mm SL.

Figure 2. – Collection localities (*) of specimens of Parabothus rotundifrons.

Figure 3. – Diagrammatic illustration of head of Parabothus rotundifrons sp. nov. A: Holotype, male, 108.5 mm SL ZIN 49152; B: P. taiwanensis, male, 108.5 mm SL, MNHN 2013-0329.

Figure 4. – Parabothus rotundifrons. A: First gill arch; B: Lateral line scale on ocular side; C: Caudal skeleton. Scale bars = 1 mm.