Choerodon (Peaolopesia) Smith, 1953

Martin F., Martin F., 2017, A review of the tuskfishes, genus Choerodon (Labridae, Perciformes), with descriptions of three new species, Memoirs of Museum Victoria 76, pp. 1-111 : 64

Choerodon (Peaolopesia) Smith, 1953

Tables 2, 5, 6

Peaolopesia Smith, 1953: 520 , type species – Xiphochilus gymnogenys Playfair & Günther , by monotypy.

Choerodonoides Kamohara, 1958: 2 , type species – Choerodonoides japonicus Kamohara (= C. albofasciatus ), by monotypy.

Diagnosis. Dorsal fin rays XII, 8 or XIII, 7; anal fin rays III, 10; pectoral fin rays ii, 13–14, rarely 14, dorsalmost ray short 2.8– 17.5% pectoral fin length; ventralmost pectoral fin ray distinctly longer than those immediately above, posterior edge of fin falcate, dorsoposterior corner bluntly pointed and posteroventral corner sharply pointed or ventralmost rays shorter than those above, posterior edge of fin obliquely straight, dorsoposterior corner bluntly pointed and posteroventral corner angular to broadly rounded; body moderately shallow, 24.4–37.7% SL, caudal peduncle depth 9.2–13.3% SL, head depth 19.4–29.22% SL; head blunt, dorsal profile of snout steep, snout length 8.0–15.5% SL; predorsal scales approximately 5–8, reaching forward on dorsal midline almost to above posterior edge of preopercle, to above posterior extent of eye or somewhere between; cheek with small partially or almost completely embedded scales in about 2–10 diagonal rows, posteriormost with about 2–10 scales to upper extent of free preopercular edge, reaching forward approaching upper lip crease above mouth, not reaching much below lower margin of eye and posterior extent of orbit, or reaching somewhere between, with broad naked margin posteriorly and ventrally on preopercle or almost completely naked cheek; 1–3 rows (only about 2 scales in second row when present) of small scales on subopercle adjacent preopercular edge extending forward to about anterior end of ventral preopercular margin, to just in advance of posteroventral corner of preopercular margin, or somewhere between, with about 5–10 scales in outermost row; each lateral line scale with unbranched to multiple branching laterosensory canal tube; scales above lateral line about 2½–3½; cephalic sensory canal pores relatively few confined to lines or short branches associated with major canals, extremely numerous on top of head, in front of and below eye and on lower jaw, or arranged somewhere between; second pair of canines in lower jaw directed anterodorsally and slightly laterally, usually curved slightly posteriorly; dorsal and anal fins with or without very low basal sheath, comprising 1 smaller scale with 1–3 smaller or progressively smaller accessory scales adjacent to fin base; posterior lobe of dorsal and anal fins reaching well short of, not quite to or to hypural crease; caudal fin margin truncate to convex. (See Table 2 for additional meristic and morphometric ranges.) Most with prominent white to pearlescent stripe or enlarged spot on body of adults, with or without distinctive sexual dimorphism. Colouration of juveniles of some unknown.

Comments. Smith published Peaolopesia as a nomen nudum first in a figure caption of a plate of illustrations (1949: pl. 101, fig. 776a; 1950: pl. 101, fig. 776a), evidently added immediately prior to publication, and for which no species treatments were provided. In the third edition of Sea Fishes of Southern Africa (1953: 520), Smith elaborated, designating Xiphochilus gymnogenys Playfair and Günther, 1867 as type species. Debate continued as to whether it and closely allied species, such as Choerodon margaritiferus Fowler and Bean, 1928 , formed a natural grouping deserving generic recognition distinct from Choerodon . Kamohara (1958: 2) faced the same dilemma when describing his Choerodonoides japonicus and was undoubtedly unaware of Smith’s name. Gomon (1997: 812) placed the two in synonymy with Choerodon but acknowledged that they represented a natural grouping that might be recognised in the future at subgeneric level.

The subgenus (fig. 1, clade 1a) comprises ten species with a relatively slender profile and very short first pectoral fin ray, seven of which have a modified falcate pectoral fin with an extended ventralmost fin ray. The rather wide range of proportional lengths for the first pectoral fin ray provided in the above description and in Tables 2, 6 and 7 is more reflective of the difficulty in determining where the distal tip is positioned beneath overlying epidermal tissue than any true variations in length. All species reach a small maximum size as adults; the smallest C. gomoni is so far known from individuals measuring 106 mm SL or less, and the largest C. aurulentus sp. nov. attains only just more than 180 mm SL. Elsewhere within the genus, only C. typus of the monotypic subgenus Xiphocheilus has a maximum length falling within this range. The subgenus may be legitimately regarded as dwarf tuskfishes.