Pteroidichthys caussei, Motomura, Hiroyuki & Kanade, Yuka, 2015

Motomura, Hiroyuki & Kanade, Yuka, 2015, Review of the scorpionfish genus Pteroidichthys (Scorpaenidae), with descriptions of two new species, Zootaxa 4057 (4), pp. 490-510 : 504-508

Pteroidichthys caussei n. sp.

[New English name: Causse’s Scorpionfish] ( Figures 2 D–F, 3D, 4–6; Table 4 )

Holotype. MNHN 2005–2607, 39.6 mm SL, Chesterfield Is., New Caledonia, 19°12′S, 158°42′E, 68 m, RV Coriolis, 17 July 1984.

Paratypes. 8 specimens, 14.5–45.3 mm SL. New Caledonia: BPBM 33821, 40.0 mm SL, Chesterfield Islands, 21°19′30ʺS, 158°51′30ʺE, 78 m, RV Alis, 21 Aug. 1988; MNHN 2015-0243, 45.3 mm SL, Chesterfield Is., 19°12′S, 158°42′E, 68 m, RV Coriolis, 17 July 1984. French Polynesia: KAUM –I. 71526, 28.3 mm SL, MNHN 2000-4558, 20.4 mm SL, Pua, Nuku Hiva, Marquesas Islands, 08°45′S, 140°13′59ʺW, 108–112 m, RV Alis, 25 Aug. 1997; MNHN 2010-0931, 22.0 mm SL, Hakahetau, Ua Pou, Marquesas Is., 09°19′59ʺS, 140°07′01ʺW, 90–92 m, RV Alis, 3 Sept. 1997; MNHN 2010-0951, 14.5 mm SL, Hana Vave, Fatu Hiva, Marquesas Is., 10°28′01ʺS, 138°40′59ʺW, 119–122 m, RV Alis, 1 Sept. 1997; MNHN 2010-0530, 2 specimens, 25.1–26.4 mm SL, Hiva Oa Island, Marquesas Is., 09°43′59ʺS, 138°51′W, 107–108 m, RV Alis, 30 Aug. 1997.

Diagnosis. A species of Pteroidichthys with the following combination of characters: anal fin with 2 spines and 6 soft rays; dorsal-fin spines rigid; snout relatively short, its length 12.3–17.2% (mean 15.1%) of SL, shorter than postorbital length; posterior margin of maxilla extending beyond vertical through middle of pupil; distance between tips of lateral lacrimal and first suborbital spines shorter than that between tips of first and second suborbital spines; supplemental preopercular spine absent; tentacles on supraocular and posterior lacrimal spines poorly developed, their lengths less than orbit diameter; few tentacles on trunk and fins; lateral lacrimal and suborbital spines well developed, with pointed tips; membranes between last spine to third soft ray and fourth to fifth soft ray of dorsal fin with large black blotch.

Description. Meristics and morphometrics of holotype and paratypes of P. caussei are shown in Table 1. Data for the holotype are presented first, followed by paratype data in parentheses (if different). Characters given in the diagnosis of the species are not repeated here.

Fourth (or fifth) dorsal-fin spine longest, its length greater than (or subequal to) upper-jaw length; fifth to eleventh spines progressively shorter; penultimate (= eleventh) spine shortest, its length less than half of length of last spine; distal margin of spinous portion of dorsal fin moderately notched; membrane of spinous portion of dorsal fin not fleshy. All soft rays of dorsal fin unbranched, except for last ray divided into 2 branches at base; posterior branch of last soft ray shortest, joined by membrane to caudal peduncle for less than one-third its length; tip of depressed posterior branch of last soft ray not reaching to vertical through posterior margin of hypural plate. Second anal-fin spine longest, its length slightly greater than (or subequal to) orbit diameter. First anal-fin soft ray unbranched; remaining rays, including posterior branch of last ray, branched; posterior branch of last soft ray shortest, not joined by membrane to caudal peduncle; tip of depressed posterior branch of last soft ray extending beyond vertical through posterior margin of hypural plate; membranes between rays weakly notched. Pectoral-fin rays unbranched; tenth ray longest, its length less than head length; membranes between upper rays weakly notched; membranes between lower rays strongly notched. Pelvic-fin spine length longer than second anal-fin spine length. All soft rays of pelvic fin branched; third ray longest, its length longer than upper-jaw length; last soft ray joined by membrane to abdomen for more than four-fifths its length; membranes between rays weakly notched. Gill rakers short and spinous, longest raker on first gill arch less than half length of longest gill filament; fourth gill slit closed by membrane. Vertebrae 24. Swimbladder absent.

Body and head strongly compressed; body width less than length of longest dorsal-fin spine. Body shallow, deepest at bases of first to third dorsal-fin spines. Head large, its length greater than body depth. Ventral surface of posterior lacrimal spine with unbranched, broad tentacle, its length less than (to equal to) depth of posterior margin of maxilla; tip of tentacle not reaching to posterior margin of maxilla when laid back. Slender tentacle on posterior margin of low fleshy rim associated with anterior nostril, not reaching to (to extending well beyond) anterior margin of posterior nostril, not reaching anterior margin of orbit when laid back. Supraocular tentacle fleshy, its margin corrugated, its length variable, but always less than orbit diameter. One pair of short tentacles on lower surface of lower jaw, its length less than length of posterior lacrimal spine tentacle. Small elliptical or circular fleshy tentacles on outer part of eye membrane. Few tentacles on lateral surface of body. Pectoral-fin axil without skin flaps.

Posterior nostril opening upward behind upper lacrimal ridge, well visible laterally. No distinct sensory pores around anterior and posterior nostrils. Underside of dentary with 3 small sensory pores on each side. Small pore behind nodular portion of lower jaw on each side. Body scales cycloid. Well-exposed scales covering an area surrounded by opercular margin and tips of upper and lower opercular spines; other parts of head not covered with exposed scales. Well-exposed scales on lateral surface of body; body scales not extending onto rays or membranes of fins, except basal caudal fin. Scales probably covering pectoral-fin base and ventral surface of body, including between pelvic fins, but scales missing. Lateral line sloping downward at tip of opercle.

Holotype Paratypes

MNHN 2005-2607 n = 8

11th dorsal-fin spine length 6.4 4.9–7.1 6.3 12th dorsal-fin spine length 19.5 19.1–19.3 19.3 Mouth oblique, forming angle of about 15 (15–20) degrees to horizontal axis of head and body. Upper edge of posterior maxilla slightly swollen laterally, forming indistinct ridge; central part of maxilla slightly convex with distinct median ridge. Lower jaw with thickened symphysial portion fitting into shallow median depression of upper jaw when mouth fully closed. Width of symphysial gap separating premaxillary teeth bands slightly greater than width of each band. Upper jaw with band of slender, conical teeth, tips of teeth strongly pointed. Three (or 2) tooth rows at front of upper jaw, tooth band narrowing posteriorly. Tooth band of upper jaw subequal in width to that of lower jaw. Lower jaw with band of slender, conical teeth. Few teeth at front of vomer, 2 or 3 rows posteriorly, forming a V-shaped patch on vomer. No teeth on palatine. Underside of lower jaw with indistinct, low longitudinal ridge medially.

Dorsal profile of snout curved sinuously, initially convex, then deeply concave. Nasal spine indistinct, with 1 (or 2) spinous points, directed dorsally. Posterior margin of ascending process of premaxilla not extending beyond vertical through posterior margin of posterior nostril. Interorbital ridges present, but poorly developed; beginning at base of supraocular tentacle and ending at posterior end of postocular bone base. Interorbital space deep, Ushaped in transverse section at level of mid-orbit; about one-third of orbit extending above dorsal profile of head. Preocular spine simple, directed dorsoposteriorly; its anterior surface with indistinct longitudinal median ridge; tip extending beyond horizontal line through upper margin of pupil in lateral view. Supraocular and postocular spines joined at base to each other; both spines simple. Tympanic spine tiny, its length greater than nasal spine. No interorbital, coronal, pretympanic spines. Occipital pit moderately deep with distinct transverse ridge in front of occipital pit, slightly curved posteromedially in dorsal view; pit surrounded laterally by tympanic spine base and anterior portion of parietal spine base; longitudinal length of pit slightly greater than width of pit. Parietal and nuchal spines well developed, both spines broadly joined at base. Sphenotic with blunt spine. Postorbital bone vertically elongate, without spinous points; located behind sphenotic spine; upper end of postorbital bone reaching anterior end of pterotic spine base. Pterotic spine simple, rounded, located just above uppermost end of preopercular ridge. Posttemporal spine simple, length of its base subequal to that of pterotic spine base; no upper posttemporal spine. Supracleithral spine simple.

Lateral surface of lacrimal with 6 low ridges radiating from center; uppermost end of upwardly directed ridge with bony protuberance directly below posterior nostril; uppermost end of dorsoanteriorly directed ridge without spines; 3 ventrally directed ridges with median ridge, tips not strongly projecting over upper lip, not forming spinous point; backward ridge with distinct median ridge and lateral lacrimal spine. Suborbital ridge moderately developed, with 3 well-developed spines; first spine located at vertical through center of eye; second and third spines adjoining, located below posterior part of orbit. Broad space between ventral margin of orbit and suborbital ridge. Suborbital pit broad and deep, front rimmed by vertical lacrimal ridge. Preopercle with 5 blunt triangular spines; first and second spines with distinct median ridge; third to fifth spines without median ridge. Upper and lower opercular spines simple with well-developed median ridge.

Origin of first dorsal-fin spine above posttemporal spine base. Posterior margin of opercular membrane extending beyond vertical through base of third dorsal-fin spine. Posterior tip of longest pectoral-fin ray extending well beyond vertical through base of first anal-fin soft ray. Origin of pelvic fin anterior to base of uppermost pectoral-fin ray; posterior tip of depressed pelvic fin just short of anus. Origin of first anal-fin spine below origin of last dorsal-fin spine.

Color of preserved specimens. Body brownish white; no distinct markings on head. Black blotch distally on membranes between second and fifth (or first and fifth) soft rays of dorsal fin; distal margin of soft-rayed portion translucent white (black in specimens less than 28.3 mm SL). Pectoral fin translucent white (fin base and posterior margin black in specimens less than 28.3 mm SL). Lower half of anal fin blackish (entire fin black in specimens less than 28.3 mm SL). Pelvic fin black. Caudal fin translucent white except for black lower one-third of fin (with 2 indistinct vertical bands on fin in specimens less than 28.3 mm SL). Color when fresh unknown.

Distribution. Known only from the Chesterfield Islands of New Caledonia and the Marquesas Islands of French Polynesia ( Fig. 6 ) where the species was collected in depths of 68– 122 m.

Etymology. Named in honor of Mr Romain Causse, a friend of the first author, who manages the fish collection of the Muséum National d’Histoire Naturelle, Paris and made specimens of the species available to us.

Remarks. Pteroidichthys caussei and P. amboinensis have the following shared characteristics: two spines and six soft rays in the anal fin (vs. 3 spines and 5 rays in P. acutus and P. noronhai ) and lacking a supplemental preopercular spine (vs. spine present). Detailed comparisons between P. caussei and P. amboinensis are given under Remarks of the latter species.

Figures

FIGURE 2. Species of Pteroidichthys with two spines and six soft rays in the anal fin. A: P. amboinensis, RMNH. PISC 5873, lectotype, 56.0 mm SL; B: P. amboinensis, AMS IB. 2977, holotype of Rhinopias godfreyi, 47.1 mm SL; C: P. amboinensis, KPM-NI 13992, 44.3 mm SL; D: P. c au s s e i n. sp., MNHN 2005 - 2607, holotype, 39.6 mm SL; E: P. c au s s e i n. sp., BPBM 33821, paratype, 40.0 mm SL; F: P. caussei n. sp., MNHN 2010 - 0931, paratype, 22.0 mm SL.

FIGURE 6. Distributional records of species of Pteroidichthys on the basis of specimens examined during this study. Circles, P. noronhai; stars, P. acutus n. sp.; triangles, P. amboinensis; diamonds, P. caussei n. sp. Literature records from the Indian Ocean (P. noronhai in the Saya de Malha Bank; P. amboinensis in the Red Sea and India) were omitted.

Tables

TABLE 4. Meristics and morphometrics, expressed as percentages of standard length, of holotype and paratypes of Pteroidichthys caussei n. sp.

Standard length (mm)	Holotype MNHN 2005-2607 39.6	Paratypes n = 8 14.5–45.3
Meristics Dorsal-fin rays Pectoral-fin rays (left / right sides)	XII, 9 15 / 15	Modes XII, 9 XII, 9 14–15 / 15 15 / 15
Anal-fin rays Scale rows in longitudinal series Pored lateral-line scales	II, 6 - -	II, 6 II, 6 34 34 18 18
Scale rows above lateral line Scale rows below lateral line Scale rows between last dorsal-fin spine base and lateral line Pre-dorsal scale rows	3 11 2 2	3 3 11–12 11 3–4 3 2–3 2
Gill rakers Morphometrics (% SL) Body depth	5 + 8 = 13 40.0	4–5 + 8–9 = 12–14 5 + 8 = 13 Means 34.3–39.4 37.2
Body width Head length Snout length	19.1 47.7 12.3	11.7–20.8 17.3 42.2–47.5 45 13.5–17.2 15.1
Orbit diameter Interorbital width at middle of eye Upper-jaw length	13.6 8.2 21.8	10.0–11.3 11.1 7.2–8.3 7.7 20.3–22.3 21.3
Postorbital length Pre-dorsal-fin length Pre-anal-fin length	19.5 38.6 65.9	15.5–17.9 17.2 37.1–41.7 38.6 65.2–69.3 67.2
Pre-pelvic-fin length 1st dorsal-fin spine length 2nd dorsal-fin spine length	37.7 12.3 -	37.8–42.4 39.9 9.8–14.7 12 13.8–17.4 15.8
3rd dorsal-fin spine length 4th dorsal-fin spine length 5th dorsal-fin spine length	20.9 23.6 19.1	19.1–23.5 20.7 20.1–22.3 22 19.3–23.0 21
6th dorsal-fin spine length 7th dorsal-fin spine length 8th dorsal-fin spine length	19.5 17.3 14.5	17.4–22.7 19.6 15.5–17.9 17 11.7–13.6 13.4
9th dorsal-fin spine length 10th dorsal-fin spine length	13.6 10.0	9.5–10.2 10.8 6.4–7.4 7.6 ......continued on the next page