Chlorurus strongylocephalus ( Bleeker, 1855 )

Zajonz, Uwe, Bogorodsky, Sergey V., Saeed, Fouad K. N., Aideed, Moteah S. & Lavergne, Edouard, 2023, Parrotfishes (Teleostei: Labridae: Scarini) of the Socotra Archipelago: Diversity and distributional biogeography, including a range extension of Scarus zufar Randall & Hoover, 1995, Zootaxa 5389 (3), pp. 301-330 : 305

Chlorurus strongylocephalus ( Bleeker, 1855)

Scarus strongylocephalus Bleeker, 1855: 439 ; holotype: whereabouts unknown; type locality: Sumatra and Java, western Indonesia.

Roundhead Parrotfish

Figure 3

Material examined: Underwater photographs.

Distinctive characters: Body depth 2.4–2.7 in SL; head very steep from mouth to above level of eye, with obvious convexity on forehead in terminal males; teeth fully fused to form dental plates, less than one-fourth covered by lips; cutting edge of dental plates distinctly denticulate; caudal fin truncate with prolonged lobes in terminal males. Meristic values: Pectoral-fin rays 15–17; median predorsal scales 4, first largest; cheek with 3 scale rows, lower row with 5–7 scales.

Colouration: Initial phase yellowish green dorsally, becoming lavender-pink on sides and ventrally. Body of terminal males green, blue anterodorsally, the scales with a vertical lavender-pink bar; head greenish blue with green blotch on opercle, edge of lips with green band; smaller males with green-yellow or green cheek; short green stripes radiating from eye in both phases.

Distribution: Oman south to Mozambique, Madagascar, and the Mascarene Islands, east to the Andaman Sea, Christmas Island, and western Indonesia. Known in the Arabian region from the eastern Gulf of Aden, Socotra Archipelago, and southern Oman (Randall 1995). Replaced in the Red Sea and Gulf of Aden by Chlorurus gibbus (Rüppell, 1829) .

Remarks: Photographed individuals match the description of Chlorurus strongylocephalus ( Randall & Bruce 1983; Randall 1995), supporting the record of Zajonz et al. (2019). The species was observed relatively frequently as solitary individual or occasionally as 2–3 individuals in all islands of the Archipelago. Encountered on Socotra Island at several northern localities in coral-dominated or rocky habitats at depths of 3– 15 m.

Figures

FIGURE 3. Chlorurus strongylocephalus. A: initial phase female, Di Hamri, Socotra Island, 4 m depth; B: initial phase male, Alameh, Socotra Island, 5 m depth; C: terminal male, Roosh, Socotra Island, 14 m depth.