Plectranthias azumanus (Jordan & Richardson), Jordan & Richardson, 1910

Gill, Anthony C., Pogonoski, John J., Moore, Glenn I. & Johnson, Jeffrey W., 2021, Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species, Zootaxa 4918 (1), pp. 1-116 : 38-46

Plectranthias azumanus (Jordan & Richardson)

Figures 10–12 ; Tables 1–17, 20–21

Common name: Azuma Perchlet

Anthias japonicus Döderlein in Steindachner & Döderlein 1883a: 49 (type locality, Tokyo, Japan; preoccupied by Anthias japonicus Bloch 1793 (= Scolopsis vosmeri ( Bloch 1792 ))).

Pseudanthias azumanus Jordan & Richardson 1910: 470 (replacement name for Anthias japonicus Döderlein in Steindachner & Döderlein 1883a ; Sagami Bay, Japan).

Plectranthias kelloggi azumanus .— Randall 1980: 147, tab. 11 (synonymy with A. kelloggi Jordan & Evermann 1903 ; recognition as valid subspecies; Japan).

Plectranthias kelloggi [non Anthias kelloggi Jordan & Evermann 1903 ].— Anderson 2018: 29 (checklist, in part).

Diagnosis. A species of Plectranthias with the following combination of characters: dorsal rays X,14–15, rarely X,14; pectoral rays 15, rarely 14; lateral line complete with 33–37 tubed scales; no antrorse serrations on lower edge of preopercle; scales with basal cteni; melanophores on caudal peduncle form a saddle that extends ventrally to about 1–2 scale rows beneath lateral line scales.

Description of Australian specimens (based mainly on 52.9 mm SL specimen; the 22.7 mm SL fragile, so checked only where data noted in parentheses). Dorsal rays X,15 (X,15), all segmented rays branched; anal rays III,7, all (all but first) segmented rays branched; pectoral rays 15/15 (15/15), upper 2 and lower 1 rays unbranched (all unbranched); pelvic fin I, 5, all segmented rays branched; upper procurrent caudal-fin rays 8 (8); lower procurrent caudal-fin rays 7 (8); principal caudal-fin rays 9+8 (9+8); branched caudal fin rays 8+7; total caudal-fin rays 32 (33); lateral line complete with 34/34 (34/?) scales; scales above lateral line to origin of dorsal fin 4/4 (4/?); scales above lateral line to base of fifth dorsal spine 3/3 (3/?); scales below lateral line to origin of anal fin 14/15 (14/14); diagonal rows of scales on cheek 8 (?); predorsal scales 35 (?), extending anteriorly to mid-nostrils; circumpeduncular scales 16 (16); gill rakers 8+14, the upper 6 rudiments; pseudobranchial filaments 12; branchiostegal rays 7.

Vertebrae 10+16 (10+16); supraneurals 3 (3); predorsal formula 0/0+0/2/1+1 (0/0+0/2/1+1); dorsal pterygiophores in interneural spaces 9–13 1/1/1/1+1/1 (1/1/1/1+1/1+1); 3 trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 18; 5 trisegmental pterygiophores associated with anal fin; terminal anal pterygiophore in interhaemal space 5; ribs present on vertebrae 3 through 10; epineurals present on vertebrae 1 through 13; parhypural and hypurals autogenous; well-developed hypurapophysis on parhypural; epurals 3; single uroneural (posterior uroneural absent); ventral tip of cleithrum with well-developed posteroventral process; proximal tip of first anal-fin pterygiophore near distal tips of parapophyses on vertebra 10.

Dorsal-fin spines without fleshy tabs on their distal tips; fourth dorsal spine longest; dorsal fin deeply incised before first segmented-fin ray (tenth spine 59.6% length of first segmented ray); second anal-fin spine longest and stoutest; anal fin rounded with third segmented ray longest; caudal fin truncate to slightly rounded, with some ray branches slightly elongated past fin margin; lower 7 pectoral fin rays somewhat thickened, with membranes between thickened rays deeply incised; tenth (eighth; counting from dorsal-most) pectoral ray longest, reaching vertical through posterior edge of anal-fin base; pelvic fins short, not reaching anus, second segmented ray longest.

Morphometric data are summarised in Table 20, along with data from four Japanese specimens.

Mouth large, slightly oblique, posterior margin of maxilla reaching vertical through posterior edge of pupil; maxilla expanded posteriorly, with long, low, lateral ridge running parallel to dorsal margin; small splint-like supramaxilla present; mouth terminal; upper jaw with pair of canine teeth laterally at front of jaws, and band of small conical teeth, 6 rows wide at symphysis, reducing to 2–3 rows posteriorly, the innermost row of teeth depressable; inner teeth either side of symphysis of upper jaw enlarged and caniniform; lower jaw with slightly enlarged pair of stout conical teeth at front of jaws, and band of small conical teeth, 5 rows wide at symphysis, reducing to single row posteriorly, 1–2 teeth in outer row on middle of lower jaw enlarged and developed as canines; inner teeth on either side of symphysis of lower jaw enlarged and caniniform; vomer with chevron of small conical teeth, 2–3 rows wide; palatine with narrow band of small conical teeth, 1–2 rows wide; ectopterygoid and mesopterygoid edentate; tongue narrow, pointed and edentate.

Opercle with 3 flat spines, middle spine longest, upper spine concealed by scales; preopercle with 17–33 serrations, these arranged along posterior margin and rear part of ventral margin of bone; interopercle with 1-2 weak serrations; subopercle with 3–5 weak serrations; posttemporal with 1–2 serrations. Anterior nostril positioned at middle of snout, tubular with small flap on posterior rim; posterior nostril at anterior border of orbit, with slightly raised rim but no flap.

Scales ctenoid with basal cteni; lateral line broadly arched over pectoral fin following body contour to caudalfin base; scales present on mandibles, no scales on chin, branchiostegal membranes, maxilla, infraorbitals or anterior part of snout; no auxiliary scales on head or body; dorsal fin with intermittent row of scales along base of fin; anal fin with low scaly sheath basally, with some small scales extending on to fin membranes; caudal fin with scaly basal sheath, with small scales extending on to basal third to half of fin membranes; pectoral fins with basal sheath and small scales extending on to fin membranes.

Colour in life: 22.7 mm SL specimen (CSIRO H 6374-17, based on photo taken prior to preservation, but after 12 years frozen; Figure 10A ): head and body pale tan, darker in interorbital area and on occiput; a short dusky grey stripe from mid-posterior orbit to above opercle; dusky grey wedge extending from anterior nape and base of third dorsal spine to point just above pectoral base, darkest on dorsal origin; indistinct dusky bar from bases of fifth through seventh dorsal spines to mid-side; dark grey bar extending from eighth dorsal spine through first segmented ray to just above anal-fin origin; short, indistinct bar extending from beneath final 2 segmented dorsal rays; caudal peduncle with dark grey saddle, extending to 1.5 scales below lateral line; fins hyaline except dark grey spot at dorsal-fin origin, and dark grey bar on mid-body extending to tips of eight through tenth dorsal spines and first segmented ray. 52.9 mm SL specimen (CSIRO H 6374-16, based on photo taken prior to preservation, but after 12 years frozen; Figure 10B ): similar to smaller specimen, except much paler; all dusky markings indistinct, except dark spot at origin of dorsal fin, mid-body bar and dark saddle over caudal peduncle.

Colour in preservative: Identical to non-preserved photos, except paler.

Habitat and distribution. A new record for Australian waters, based on two specimens collected off Geraldton , Western Australia, in 252–253 m ( Figure 11 ). Outside of Australia, the species is known from Japan and Taiwan, at depths ranging from 60–280 m. We attribute the lack of records from intervening areas, such as the Philippines and Indonesia, to the paucity of deep reef sampling with gear types to collect small fishes.

Comparisons. Plectranthias azumanus resembles P. kelloggi ( Jordan & Evermann, 1903) from the Hawaiian Islands and associated seamounts and islands, P. maculicauda from southeastern Australia and the Southwest Pacific, and P. melanesius from off southeast Queensland, Lord Howe Island and New Caledonia in having a more-or-less barred body coloration (coalesced into a broad wedge in P. kelloggi ) with a spot, bar or saddle over the caudal peduncle and a small spot on the caudal fin near the base of the upper rays. The four species also share the following combination of characters: segmented dorsal rays usually 15 (sometimes 14 or 16); predorsal formula 0/0+0/2/1+1; dorsal pterygiophores in interneural spaces 9–13 usually 1/1/1/1+1/1 or 1/1/1/1+1/1+1; pectoral rays usually 15 (sometimes 14 or 16); lateral line complete; relatively high number of total gill rakers (19 or more); no antrorse serrations on the lower edge of the preopercle; and scales with basal cteni. The four species differ in number of lateral-line scales, head scalation, number of gill rakers and in live coloration details; these are summarised in Table 21. These comparisons are somewhat compromised by the small sample sizes for P. melanesius , as well as the discrepancy in the sizes of specimens for which we have live coloration information. Moreover, it is possible that P. melanesius and P. azumanus are synonyms (see Remarks for P. melanesius ).

Remarks. This species was first described as Anthias japonicus by Döderlein in Steindachner & Döderlein, 1883a based on an unspecified number of specimens from Tokyo, Japan. Jordan & Richardson (1910) later noted that this name was preoccupied by A. japonicus Bloch, 1793 (= Scolopsis vosmeri ( Bloch, 1792)) , and proposed Pseudanthias azumanus as a replacement name. They included the species in their new subgenus Zalanthias , along with the type species, Anthias kelloggi Jordan & Evermann, 1903. Katayama (1959, 1960) subsequently recognised Zalanthias as a distinct genus. In his revision of Plectranthias, Randall (1980) not only considered Zalanthias a synonym of Plectranthias , but also considered P. azumanus a synonym, though valid subspecies, of P. kelloggi and erected an additional subspecies, P. kelloggi melanesius , for five specimens from New Caledonia. The nominate subspecies of P. kelloggi (known from the Hawaiian Islands and other islands and seamounts northwest along the Hawaiian Ridge to the southern Emperor Seamount Chain; Kharin & Balanov 2013) has modally higher numbers of lateral line scales and gill rakers and differs markedly in coloration from either of the remaining nominal subspecies ( Figures 10 , 12–13 ; Table 21). We recognise P. azumanus as a full species, because recognition as a subspecies is at odds with treatment of similar variation between Plectranthias species and makes an unsupported assumption that P. kelloggi and P. azumanus form a monophyletic group to the exclusion of other species such as P. maculicauda (which more closely resembles P. kelloggi in coloration). We also acknowledge various other objections to subspecies as noted by Gill (1999) and Gill & Kemp (2002). We further recognise P. melanesius as a valid species, though with less certainty (see Remarks for P. melanesius ).

In their recent checklist of serranid fishes, Parenti & Randall (2020) confused the nomenclature and spelling of Randall’s (1980) P. kelloggi subspecies: “ Randall (1980) regarded as valid subspecies the three population [sic] described from Japan ( japonicus ), Hawaiian Ids ( azumanus ), and New Caledonia (melanesicus)” ( Parenti & Randall 2020: 27).

The two specimens collected off Geraldton, Western Australia, are identified as P. azumanus based in part on a 99.82% match of CO1 DNA sequence with a specimen from central Tosa Bay, off Kochi City, Kochi, Shikoku Island, Japan (BSKU 59611; Genbank sequence MF991323 ). The Tosa Bay specimen was also the basis for Smith & Craig’s (2007) sequence data for Zalanthias kelloggi . The Tosa Bay specimen was examined in this study, along with three specimens from Sagami Bay. The specimens are slightly to much larger than either of the two Western Australian specimens, making comparison of some characters difficult. Furthermore, we lack fresh coloration information for the Western Australian specimens; although the specimens were photographed prior to preservation, they had been frozen for 12 years prior to this. Apparent differences in coloration, in particular the absence of red coloration so that only black pigmentation is visible (cf. Figures 10 , 12 ), are likely a consequence of freezing. In other features, they do not differ appreciably from the Japanese specimens, and we therefore conclude they are conspecific.

Material examined. Western Australia. CSIRO H 6374-16 , 52.9 mm SL, CSIRO H 6374-17 , 22.7 mm SL, northwest of Geraldton , 27°55.72′S, 113°08.28′E to 27°56.02′S, 113°08.64′E, 252–253 m, FRV Southern Surveyor , 4 Dec 2005 (field station number SS1005/99). Japan. BSKU 0059611 , 70.0 mm SL, Shikoku, off Kochi City, central Tosa Bay , ca 175 m, otter trawl, RV Kotaka-maru , 26 Aug 2002; KPM-NI 0007325 , 61.0 mm SL, Honshu, western part of Sagami Bay, off Manazuru , 89 m, S. Ueshima, 24 Jun 2000; KPM-NI 0018949 , 54.5 mm SL, western part of Sagami Bay, off Hatsu-shima Island , 60–80 m, Y. Miyazaki, 30 Apr 2007; KPM-NI 0037876 , 94.5 mm SL, western part of Sagami Bay, off Fukuura , 90 m, Y. Ogawa, 9 Jan 2015 .

Figures

FIGURE 10. Plectranthias azumanus, northwest of Geraldton, Western Australia. Specimens frozen for 12 years prior to photography. A) CSIRO H 6374-17, 22.7 mm SL; B) CSIRO H 6374-16, 52.9 mm SL. Photos by C. Devine, CSIRO.

FIGURE 11. Distribution records for Australian specimens of Plectranthias azumanus (triangle), P. melanesius (open circles) and P. nanus (closed circles).

FIGURE 12. Plectranthias azumanus, freshly dead, from the western part of Sagami Bay, Honshu, Japan:A) KPM-NI 0037876 (=KPM-NR108312B), 94.5 mm SL, off Fukuura; B) KPM-NI 0018949 (=KPM-NR 58452A), 54.5 mm SL, off Hatsu-shima Island. © Kanagawa Prefectural Museum. Photos by (A) Y. Miyazaki, (B) H. Senou.

FIGURE 13. Plectranthias kelloggi, BPBM 14188, 147 mm SL, Hawaiian Islands, USA. Photo by J.E. Randall.