Trachyscorpia (Mesoscorpia) longipedicula, Hiroyuki Motomura, Peter R. Last & Gordon K. Yearsley, 2007

Hiroyuki Motomura, Peter R. Last & Gordon K. Yearsley, 2007, Two new species of the scorpionfish genus Trachyscorpia (Sebastidae: Sebastolobinae) from the southern Indo-West Pacific, with comments on the distribution of T. eschmeyeri., Zootaxa 1466, pp. 19-34 : 28-33

Trachyscorpia (Mesoscorpia) longipedicula , new species

New English name: Stylish Scorpionfish

Figures 1C-D, 3; Table 1

Material examined. Holotype. CSIRO H 5370-04 , 218.7 mm SL, South-West Indian Ridge, southwestern Indian Ocean , 39°01’S, 46°31-32’E, 635-970 m depth , J. Parkinson and C. Sutherland, FV Austral Leader, 17 Nov. 1999.

Paratypes. Six specimens, 128.4-204.5 mm SL, all from South-West Indian Ridge, southwestern Indian Ocean . CSIRO H 5343-14 , 128.4 mm SL, 36°38-39’S, 52°04-05’E, 801-1027 m depth , J. Parkinson and C. Sutherland, FV Austral Leader, 29 Oct. 1999 ; CSIRO H 5343-15 , 188.9 mm SL, same data as CSIRO H 5343-14 ; CSIRO H 5343-16 , 187.4 mm SL, same data as CSIRO H 5343-14 ; CSIRO H 5370-03 , 160.4 mm SL, same data as holotype ; CSIRO H 5798-01 , 201.1 mm SL, 39°01’S, 46°01’E, 760-1080 m depth , R. Ashworth and T. Cantwell, FV Southern Champion, 6 June 2000 ; CSIRO H 5821-04 , 204.5 mm SL, 39°01’S, 46°31-33’E, 620 m depth , J. Parkinson and L. Lever, FV Southern Champion, 29 Oct. 2000 .

Diagnosis. A species of Trachyscorpia with the following combination of characters: dorsal-fin spines 13; vertebrae 26; tympanic spines present; upper-jaw lip well developed, covering premaxillary tooth band laterally; no scales on lateral surface of maxilla; 50-53 scale rows in longitudinal series; second pelvic-fin soft ray long (23.1-29.2% SL, mean 25.5%), longer than upper-jaw length; body deep (depth 37.9-40.5% of SL, mean 39.2%); orbit diameter large (15.1-18.1% of SL, mean 16.3%); pelvic-fin spine long (14.8-17.1% of SL, mean 15.6%); first anal-fin spine long (8.0-9.4% of SL, mean 8.5%); head profile convex; swimbladder present; head and trunk whitish with two blackish bands from eye on head, and 4 blackish saddles on body in preserved specimens.

Description. Proportional measurements of the specimens of T. (M.) longipedicula sp. nov. are given as percentages of SL in Table 1. In the description below, data for the holotype are presented first, followed by data for paratypes (if different) in parentheses.

Dorsal fin with 13 spines and 9 soft rays (8 rays in CSIRO H 5343-15); all soft rays branched; length of first spine 2.1 (1.9-2.1; mean 2.0) in second spine; third spine longest, its length slightly less than orbit diameter; third to twelfth spines progressively shorter; length of twelfth spine 1.4 (1.3-1.5; mean 1.4) in last spine; membrane of spinous portion of dorsal fin moderately notched; second soft ray (first ray in CSIRO H 5343- 14) longest, its length longer than that of longest dorsal-fin spine; posterior branch of last soft ray joined by membrane to caudal-fin peduncle for less than one-third its length. Anal fin with 3 spines and 5 soft rays; all soft rays branched; first spine 2.0 (1.9-2.3; mean 2.1) in second spine, 1.6 (1.4-1.8; mean 1.7) in third spine; second soft ray (first ray in five paratypes) longest, its length longer than that of second anal-fin spine; posterior branch of last soft ray not joined by membrane to caudal-fin peduncle. Pectoral fin with 21 rays on each side of body (20 rays on each side in CSIRO H 5343-15; 22 rays on each side in CSIRO H 5798-01; asymmetrically21 and 22 in CSIRO H 5343-16), the uppermost ray unbranched, remaining rays branched; fourth ray longest (fifteenth ray in smallest paratype CSIRO H 5343-14; fifth to seventh ray in other paratypes), its length slightly longer than upper-jaw length; posterior margin of fin bilobed, fifteenth to seventeenth rays progressively longer; rays in lower lobe thickened, fleshy. Pelvic fin with 1 spine and 5 soft rays, all soft rays branched; entire first to third rays and base of fourth and fifth rays covered with thick fleshy skin; second soft ray longest, its length slightly longer than upper-jaw length; last soft ray joined by membrane to abdomen for more than one-third its length. Caudal fin with 16 (17) segmented rays, 13 (13 or 14) rays branched, 3 (3 or 4) remaining rays unbranched; dorsal procurrent rays 5 (5 or 6), ventral rays 5 (4-6); posterior margin of fin nearly straight. Caudal-peduncle depth 1.6 (1.6-1.9; mean 1.7) in caudal-peduncle length.

Scale rows in longitudinal series 51 (50 in CSIRO H 5343-15; 53 in CSIRO H 5821-04; uncountable in remaining paratypes). Pored lateral-line scales 27. Scales below lateral line 17 (15 in CSIRO H 5343-15). Scale rows between base of sixth dorsal-fin spine and lateral line 7. Predorsal scale rows 10 (9 in three paratypes). Gill rakers on upper limb 4 (5 in all paratypes), lower limb 12 (13 in four paratypes), including 3 (4 in three paratypes) rakers on hypobranchial; total gill rakers 16 (17 in CSIRO H 5343-14, -15; 18 in all other paratypes). Gill rakers relatively short and spinous with numerous serrae, longest raker on first gill arch shorter than gill filaments around angle of gill arch; fourth gill slit closed by membrane. Swimbladder present. Vertebrae 26.

Body moderately compressed anteriorly, progressively more compressed posteriorly. Nape and anterior body not strongly arched. Body relatively deep, depth less than head length. No distinct small papillae on head. Several short, slender tentacles on dorsal margin of eye membrane. A short, slender tentacle, its length less than posterior nostril diameter, on posterior end of preocular, supraocular and postocular spine bases. A short tentacle on posterodorsal edge of low membranous tube associated with anterior nostril; length of tentacle greater than anterior nostril diameter. No tentacles on occiput, mid-interorbital space, snout, maxilla, lips, underside of lower jaw, preopercle, opercle, fins and lateral surface of body. Pectoral-fin axil without skin flaps.

Exposed ctenoid scales covering interorbital space, occiput, opercle and an area surrounded by tympanic, pterotic, parietal, nuchal and lower posttemporal spines. Cycloid scales covering cheek and an area surrounded by posterior margin of orbit, pterotic spine, preopercular margin and suborbital ridge. Other parts of head not covered with exposed or embedded scales. Well-exposed ctenoid scales on lateral surface of body, scales becoming cycloid on ventral surface. Body scales extending on to basal rays and membranes of all fins, except pelvic fins; scales on fins cycloid. Exposed cycloid scales covering pectoral-fin base and anteroventral surface of body; some scales embedded in thin skin. Lateral line strongly sloping downward at tip of opercle.

Sensory pores of cephalic lateralis system prominent; 3 large pores on cheek just below suborbital ridge, first pore just below posterior end of lacrimal bone, second pore below posterior margin of orbit, third below end of suborbital ridge. Underside of dentary with 3 sensory pores on each side, first pore below anterior to tip of anterior lacrimal spine, second pore below and between tips of anterior and posterior lacrimal spines, third pore located on posterior margin of dentary; second pore covered with thin skin (not covered with skin in smaller paratypes, CSIRO H 5343-14, H 5370-03). A small pore behind symphysial knob of lower jaw on each side; an indistinct pore on each side of symphysial knob.

Mouth large, slightly oblique, forming an angle of about 20 (20-25) degrees to horizontal axis of head and body. Posterior margin of maxilla extending slightly beyond a vertical through posterior margin of orbit (just reaching in CSIRO H 5798-01, not reaching in other paratypes). Upper edge of posterior maxilla slightly swollen laterally; central part of maxilla slightly convex, but not forming a ridge. Lower jaw with a symphysial knob. Width of symphysial gap separating premaxillary teeth bands greater than width of each band. Tooth band of upper jaw wider than that of lower jaw. Upper jaw with a band of villiform teeth; tooth band narrowing posteriorly. Lower jaw with a band of villiform teeth; lengths of most teeth subequal to those of upper jaw. Vomer V-shaped; one tooth patch anteriorly and one patch posterolaterally on each side, with naked areas between (naked areas indistinct in CSIRO H 5343-15, H 5343-16); anterior patch rounded, posterolateral patches elongate. Width of vomerine plate less than length of palatine plate. Palatine teeth in about 1 or 2 rows, teeth becoming shorter posteriorly. Underside of lower jaw smooth, without ridges.

Dorsal profile of snout steep, forming an angle of about 55 (50-55) degrees to horizontal axis of head and body. Nasal spine simple, sharp, directed dorsally, its length much greater than posterior nostril diameter. Ascending process of premaxilla slightly intruding into interorbital space, its posterior margin reaching level with middle of preocular spine base in dorsal view. Median interorbital ridge absent. Interorbital ridges separated by a shallow channel, beginning posterior to nasal spines and joining at origin of tympanic spines; interorbital ridges unbranched, diverging anteriorly and posteriorly in dorsal view, distance between interorbital ridges narrowest at a vertical through anterior margin of pupil. Interorbital space moderately deep, about oneeighth of orbit extending above dorsal profile of head. Preocular spine simple, directed dorsally; tip of spine extending beyond level with upper margin of pupil in lateral view. Supraocular spine simple, its length shorter than those of preocular, postocular and tympanic spines. Postocular spines simple, strongly canted laterally. Tympanic spine simple, strongly pointed, directed dorsally, its length longer than (subequal in CSIRO H 5343-15, H 5343-16) that of postocular spine. Interorbital, coronal and pretympanic spines absent. Occiput nearly flat, lacking pit; longitudinal length of pit greater than width; occiput surrounded laterally by tympanic spines, parietal spines, and indistinct low ridges between tympanic and parietal spines. Parietal spine simple, smaller than nuchal spine. Nuchal spine simple; nuchal and parietal spines joined at base. Sphenotic with several small spines. Postorbital spines absent on left side of head (several small spines present on right side of head in holotype; small spines present in all paratypes). Pterotic spine simple, located below parietal and nuchal spines. No ridges in an area surrounded by parietal, nuchal, pterotic and lower posttemporal spines. Upper posttemporal spine absent. Lower posttemporal spine simple, its base length less than that of pterotic spine. Supracleithral spine simple, not strongly pointed. Cleithral spine flattened, with a point.

Lateral lacrimal spine simple, strongly pointed (2 spines on right side in CSIRO H 5821-04; 2 spines on left side and 3 spines on right side in CSIRO H 5343-15). Lateral surface of lacrimal with 6 elements radiating from center; a backward ridge with a distinct median ridge, other ridges with a low median ridges; 2 downward ridges forming anterior and posterior lacrimal spines; anterior ends of 2 forward ridges and dorsal end of an upward ridge embedded in skin. Anterior lacrimal spine pointed, directed ventrally (ventroposteriorly), its tip not reaching (just reaching) dorsal margin of upper lip; no additional spine occurring at base of anterior lacrimal spine. Posterior lacrimal spine simple, directed ventroposteriorly, its tip not reaching upper lip; posterior lacrimal spine greater than anterior spine. Suborbital ridge with 5 spines (6 spines on left side of head in holotype; usually 5 spines, sometimes 6 spines), first and second spines below pupil, third spine below posterior margin of orbit, fourth and fifth spines between posterior margin of orbit and preopercular margin. Space between ventral margin of eye and suborbital ridge remarkably narrow. Suborbital pit absent. Preopercle with 5 spines; uppermost spine largest with a supplemental preopercular spine on its base; second to fifth spines without a distinct median ridge. Preopercle, between uppermost preopercular spine and upper end of preopercle, smooth without serrae or spines. Upper opercular spine simple without a median ridge. Lower opercular spine simple with a low median ridge. Space between upper and lower opercular spines without ridges. Posterior tips of upper and lower opercular spines not reaching opercular margin.

Origin of first dorsal-fin spine above posterior end of supracleithral spine. Posterior margin of opercular membrane reaching a vertical through fourth dorsal-fin spine base (not reaching in three paratypes). Posterior tip of pectoral fin extending beyond a vertical through tenth dorsal-fin spine and not reaching anal-fin origin. Origin of pelvic-fin spine slightly posterior to origin of pectoral fin. Posterior tip of depressed pelvic fin extending beyond anus and a vertical through posterior tip of pectoral fin (just reaching posterior tip of pectoral fin in CSIRO H 5343-16). Origin of first anal-fin spine slightly posterior to origin of last dorsal-fin spine.

Color when fresh. Head and body mainly pale reddish, with blackish markings on head, dorsal half of trunk, dorsal fin, pectoral fin and pectoral-fin base (Figs. 1C -D). Color when alive is unknown.

Color of preserved specimens. Head and body yellowish-white dorsally, whitish ventrally. Two blackish broad bands on head; one running from middle of ventral margin of eye to fifth preopercular spine through under dorsal angle of posterior margin of maxilla; the other running from posterior margin of eye to dorsal end of opercle. Anterior nostril tentacle black distally. Inside of opercle dense black. Four blackish saddles; first saddle above opercle, including membranes between first and third dorsal-fin spines; second saddle broadest, extending from basal half of membranes between fifth (or sixth) and eleventh dorsal-fin spines to below lateral line; third saddle extending from basal membranes of dorsal-fin soft rays to above lateral line; fourth saddle on posterior caudal-fin peduncle, reaching ventral surface of caudal-fin peduncle. Distal half of membranes between fourth and eleventh dorsal-fin spines dense black, forming an elongate black blotch. A poorly defined blackish blotch on middle of soft rayed portion of dorsal fin. Two poorly defined blackish blotches on base and middle of pectoral fin. Pelvic fin yellowish without melanophores. Anal fin yellowish with 2 black spots (black spots absent in all paratypes). Caudal fin yellowish with a few scattered melanophores. Abdominal cavity lining dense black.

Distribution. Currently known only from the South-West Indian Ridge, southwestern Indian Ocean, between ca. 36° and 39°S, and 46° and 52°E (ca. 1,700 km south of southern tip of Madagascar), at depths of 620-1080 m. Trachyscorpia longipedicula co-occurs with T. eschmeyeri .

Etymology. The specific name longipedicula is derived from the Latin longus meaning long, and pediculus meaning foot, in reference to the long pelvic-fin spine and rays, and first anal-fin spine, compared with the short spines and rays of T. carnomagula and T. eschmeyeri . A new English name, Stylish Scorpionfish, is proposed here for this species.

Discussion

The subgenus Mesoscorpia Eschmeyer .

The subgenus Mesoscorpia was proposed for Trachyscorpia capensis (Gilchrist & von Bonde, 1924) (= T. eschmeyeri Whitley, 1970 ; see Introduction) by Eschmeyer (1969). In addition, Eschmeyer (1969) placed T. cristulata cristulata and T. cristulata echinata in the subgenus Trachyscorpia Ginsburg, 1953 . He distinguished Mesoscorpia from Trachyscorpia by its species having 13 dorsalfin spines (vs. 12 in the latter) and 26 vertebrae (vs. 25), and lacking tympanic spines (vs. spines present). Two of 29 specimens of T. eschmeyeri (= T. capensis of Eschmeyer, 1969) examined during the present study had 12 dorsal-fin spines instead of 13 spines. The number of dorsal-fin spines, especially when either 12 or 13, has been recognized as an important generic or subgeneric character in scorpionfishes (e.g., Cadenat, 1943; Eschmeyer, 1969), and the presence of 12 spines is diagnostic of the subgenus Trachyscorpia . These two specimens also had 26 vertebrae instead of 25. As a change in the number of dorsal-fin spines is usually associated with a corresponding change in vertebrae number in scorpionfishes, a single spine reduction in these specimens is most likely to be a genetic or ontogenetic defect. Accordingly, we agree that T. eschmeyeri belongs to the valid subgenus Mesoscorpia , and 13 dorsal-fin spines and 26 vertebrae are diagnostic characters for the group.

Remarkable intraspecific variation exists for T. eschmeyeri in the presence ( Trachyscorpia ) or absence ( Mesoscorpia ) of the tympanic spines (Eschmeyer, 1969). Examination of the 29 specimens of T. eschmeyeri showed that 19 specimens (ca. 65%) lacked the tympanic spines on either side of the head, 6 specimens (21%) had the spine on only one side of the head and 4 specimens (14%) had the spines on both sides. The presence or absence of the tympanic spines is not useful as a diagnostic subgeneric character.

Both two new species invariably had 13 dorsal-fin spines, 26 vertebrae and tympanic spines on both sides of the head. Based on the foregoing subgeneric character assessments, we herein classify the two new species within Mesoscorpia .

Eschmeyer (1969) included the absence of a swimbladder as a diagnostic character of the genus Trachyscorpia , but did not specify for which specimens or species this character state was observed. Ragonese and Giusto (1999) reported that a swimbladder was absent in T. (T.) cristulata echinata . Our examinations of three species of the subgenus Mesoscorpia , T. carnomagula , T. eschmeyeri and T. longipedicula , revealed that all species have a swimbladder. It is most likely that Eschmeyer’s description (absence of swimbladder) was based only on T. (T.) cristulata [he examined numerous specimens of T. (T.) cristulata , but only a single specimen of T. (M.) eschmeyeri (as capensis )]. We herein recognize the presence or absence of a swimbladder as the third character for separating the subgenera Trachyscorpia and Mesoscorpia .

Comparisons. The new scorpionfishes, Trachyscorpia (Mesoscorpia) carnomagula and T. (M.) longipedicula , can be easily distinguished from the only other member of the subgenus, T. (M.) eschmeyeri , by the upper-jaw condition. The two new species have a fleshy upper-jaw lip covering the premaxillary tooth band laterally (Fig. 2A), whereas T. eschmeyeri lacks a fleshy lip, except on the posterior end of the premaxilla, and the premaxillary teeth are exposed laterally (Fig. 2B). The lateral surface of the maxilla in T. carnomagula and T. longipedicula is smooth, lacking scales (Fig. 2A), whereas that in T. eschmeyeri is covered with cycloid scales posteriorly (Fig. 2B). In addition, the two new species also differ from T. eschmeyeri in having a deeper body (depth 34.3-42.5% of SL, mean 38.0% in carnomagula and 37.9-40.5%, mean 39.2% in longipedicula vs. 32.0-34.8%, mean 33.6% in eschmeyeri ; Fig. 3A) and a larger orbit diameter (14.1-18.0% of SL, mean 16.1% in carnomagula and 15.1-18.1%, mean 16.3% in longipedicula vs. 12.1-14.1%, mean 13.0% in eschmeyeri ; Fig. 3B). Furthermore, the head profile of the two new species is convex, like that of most species of Scorpaena (see Fig. 1A-D), whereas that of T. eschmeyeri is concave (in adults) or straight (in young) (see Fig. 1E-F). Eyes of the two new species are oriented more laterally, compared with dorsolaterally oriented eyes of T. eschmeyeri .

Coloration of the two new species is also substantially different from T. eschmeyeri , although all species are tinged with red when fresh. The two new species have two dark bands on the head (originating from the eye) and four dark saddles on the body (these markings being more distinct in preserved specimens), whereas T. eschmeyeri lacks those markings on the head or body. Trachyscorpia eschmeyeri exhibits sexual dichromatism, with probable males (20 specimens examined in this study) having a large black blotch on the spinous portion of the dorsal fin (Fig. 1F), which is missing in females (9 specimens). On the other hand, all specimens of the two new species had a large black blotch on the membranes between the fourth and eleventh dorsal-fin spines, indicating that the two species do not exhibit sexual dichromatism. The dark dorsal-fin blotch of the two new species is normally restricted to the distal half of the fin membrane, whereas the blotch in male T. eschmeyeri normally extends proximally onto the membrane base. Furthermore, in preserved specimens, the membranes between the first and third dorsal-fin spines of the two new species are blackish, whereas those of T. eschmeyeri are whitish.

Trachyscorpia carnomagula differs from T. longipedicula in having 57-63 scales rows in longitudinal series (vs. 50-53 in the latter), a shorter pelvic-fin spine (9.4-15.9% of SL, mean 12.4% vs. 14.8-17.1%, mean 15.6%; Fig. 3C), a shorter second pelvic-fin soft ray (17.9-24.9%, mean 20.3 vs. 23.1-29.2%, mean 25.5; Fig. 3D), and a longer first anal-fin spine (5.1-7.7%, mean 6.4% vs. 8.0-9.4%, mean 8.5%). The second pelvic-fin soft ray of T. carnomagula is shorter than the upper-jaw length, whereas this fin ray is longer than the upper-jaw length in T. longipedicula .