Serranus (Paracentropristis) drewesi Iwamoto, 2018

Iwamoto, Tomio & Wirtz, Peter, 2018, A Synopsis of the Eastern and Central Atlantic Combers of the Genus Serranus (Teleostei: Scorpaeniformes: Serranidae), Proceedings of the California Academy of Sciences 65 (1), pp. 1-39 : 11-13

Serranus (Paracentropristis) drewesi Iwamoto , sp. nov.

Figure 8

DIAGNOSIS.— D X,11; P 14; A III,6; gill rakers 3+11; scales below 1D origin about 5, below 2D 4+1+8 or 9, pored lateral-line scales 44; circumpeduncular scales 1+9+1+10 (21 total). Anteri- or nostril tubular, rim greatly elevated posteriorly and bearing about 7 or 8 long cirri at tip. Scales all cycloid (except for a hard, sharply spinulated suprascapular scale bone above the upper opening of the gill cover). Caudal fin weakly emarginate, upper and lower lobes about equal. Interradial membranes of soft dorsal and anal fins scaly on basal one-half to one-third. Nape, opercle, preopercle, interopercle, mandibular ramus, pectoral-fin base, and chest covered with cycloid scales. A bold black spot between last three spines and first soft dorsal ray formed above broad black saddle on dorsal half of body.

DESCRIPTION.— Head and body laterally compressed, greatest width of head 6.3 times in SL, greatest body width 5.9 times in SL. Snout pointed, longer than orbit diameter; interorbital space narrow, bony width about 60% of greatest orbit diameter. Orbit about 4 in HL; pupil sharply eggshaped with pronounced anterior aphakic (lensless) space. Jaws equal; posterior margin of maxilla below middle of orbit. Two broad, flat, weak opercular spines developed, the dorsal spine partially obscured by skin and scales, lower spine more prominent and forming posterodorsal corner of gill cover. Anterior nostril tubular, rim low anteriorly but elevated into a long flap posteriorly, the flap fringed with 7 or 8 long cirri, a few filaments longer than height of flap. Gill opening ventrally extending forward to about vertical passing through hind edge of orbit. Gill rakers relatively short, stout and recurved, the uppermost on lower limb (ceratobranchial) about 1.5 mm in length, the succeeding rakers gradually shorter with last three or so tubercular. About 11 pseudobranchs.

Spinous dorsal fin with middle spines longest, a prominent dip between spinous and soft-rayed portions of dorsal fin; the longest dorsal spine shorter than longest dorsal soft rays. Size and shape of pectoral fin could not be determined owing to left fin torn off in capture and right fin cut off for tissue sample. Pelvic fin below fourth spine of dorsal fin and behind origin of pectoral fin, its tip when depressed not extending to origin of anal fin. Anal fin with three strong spines, the first about half length of second, which is slightly longer than third spine; six soft rays forming narrow round- ed tip to fin. Caudal fin weakly emarginate.

Scales all cycloid (excepting a hard, sharply spinulated suprascapular scale bone above the upper opening of the gill cover). Snout and dorsal surfaces of head naked anterior to a vertical passing through hind margin of preopercle. Interopercle finely scaled anteriorly and dorsally immediately below preopercular margin. Mandibular ramus with tiny thin scales covering most of posterior surfaces and extending forward onto lateral surfaces. Cheeks (viz, preopercle) finely scaled; hind (vertical) margin of preopercle finely serrated, but ventral margin smooth. Opercle and subopercle with large scales in two major rows bordered posteriorly with small scales. Chest and nape fully scaled. Eight scale rows along dorsal crest of nape before origin of first dorsal fin. Small scales at base of second dorsal fin (and sparsely on posterior base of spinous dorsal fin), and on bases of pectoral and caudal fins.

Anterior tip of premaxillary with cluster of small teeth and one enlarged canine more laterally placed; the cluster of teeth followed by a tapered band of small teeth. Dentary teeth consist of a cluster of small, short, conical teeth anteriorly that are rigid along outer margin but depressible inward of outer row. Posterior to these, a series of four larger canine-like teeth, with an outer small- er tooth row, these in turn followed posteriorly by a row of smaller teeth. Vomerine teeth small, in a broad short band. Presence of palatine teeth could not be adequately assessed for fear of damaging specimen; however, there appeared to be a row of small teeth along the bone.

Color (fresh): ( Fig. 8 ) Head with five or six small black spots behind eye, two in interorbital space, one on snout on median line, and diffuse ill-defined spots on sides of snout and head. Dorsal half of body and head darker than ventral half; nape and dorsum posteriorly to below third dorsal spine dark brown; a broad dark saddle below last three spines and first two soft rays of dorsal fin; a second dark saddle below 5 th through 9 th soft rays, followed by third saddle (partially merged with second) below last two soft rays and anterior one-third or so of caudal peduncle, a fourth saddle on posterior third of caudal peduncle ending sharply at base of caudal fin. Spinous dorsal fin irregularly brown with faint pale blotches, a bold black spot between posterior part of spinous dorsal and anteriormost end of soft dorsal fin; pectoral fin missing on both sides; pelvic fins pale to light yellow; anal fin dark brown overall; caudal fin mostly orangish to pink with darker upper and lower edges. Iris orange.

Comparisons: Serranus drewesi is most similar in overall characters to S. hepatus , notably in having six anal fin rays and closely similar fin ray counts, somewhat similar body shape, and general color pattern, including a prominent black spot on the dorsal fin. That spot, however, is not ocellated as in S. hepatus and it merges with the broad saddle on the dorsum immediately below. The saddles on the body do not extend to the ventral body margin and do not sharply contrast with a generally pale body as in S. hepatus . The pelvic fin is overall yellowish (dusky in preserved specimen) in contrast to black in S. hepatus and the anal fin is uniformly dark brown without the pronounced black anterior and clear distal parts so notable in S. hepatus . Other differentiating features include: the absence in S. drewesi of narrow gold to orange stripes on the head (vs. present in S. hepatus ); black spots on the head (lacking in S. hepatus ), two opercular spines in S. drewesi (vs. three); snout longer than orbit (vs. about equal to); gill rakers on first arch 14 total (3+1+10) (vs. 19-23); long cirri on flap of anterior nostril 7 or 8 (vs. 1-3 stubby cirri); cycloid scales on body (vs. ctenoid scales); circumpeduncular scale rows 21 (vs. 23-26); scale rows below origin of dorsal fin 5 (vs. 6-8); interorbital space naked (vs. scaled); mandibular ramus finely scaled (vs. naked).

Serranus drewesi is readily differentiated from S. scriba , S. cabrilla , and S. atricauda by its fewer lateral-line scales and its distinctive color pattern. The combination of relatively low fin-ray counts of soft dorsal, pectoral, and anal fins, and the fewer gill rakers, the absence of ctenoid scales, as well as the color pattern, which includes a large black spot on the dorsal fin, distinguish the new species from the remaining eastern Atlantic species of the genus.

Size: To at least 6.5 cm TL

DISTRIBUTION.— Known only from the holotype taken by mini-spear in a submarine cave in Santana Islet , Republic of São Tomé e Príncipe .

ETYMOLOGY.— Named in honor of Dr. Robert C. Drewes of the California Academy of Sciences, for his dedicated efforts in leading 12 separate scientific and educational expeditions to São Tomé e Príncipe to explore and document the diverse fauna and flora of that country and to inspire and educate the country’s citizens as to the biological wealth and uniqueness of where they live.

REMARKS.— We describe this species with some reluctance owing to the absence of additional specimens and the small size of the only representative. We did not examine the internal organs, notably the gonads, to determine whether it is a juvenile or an adult. If the former, it is likely that the adult pigmentation pattern of this species differs substantially from the holotype. We also did not examine the myological, arthrological, and osteological characters used by Meisler (1987:80) defining the subgenera Paracentropristis and Serranus (e.g., levator arcus palatini muscle inserts on preopercle and dorsal origin of ethmomaxillary ligament medial on mesethmoid). We await the collection of additional specimens to expand on the description of this obscure little species.

TYPE SPECIMEN.— Holotype, CAS 234050 (53.5 mm SL); São Tomé e Príncipe, São Tomé Is.; Santana Islet (0°14ʹ33.1ʺN, 6°45ʹ36.1ʺW); collected by J.E. McCosker and J.-L. Testori in submarine cave at 62 ft [18.9 m] depth; 28 Jan. 2009; mini-hand spear.

Figures

FIGURE 8. Serranus drewesi Iwamoto, new species. Holotype (CAS 234050 (53.5 mm SL) from submarine cave on Santana Islet, São Tomé Island. Photograph by David Catania.