Comactinia

Comactinia AH Clark, 1909

Table 1

Type species. Comactinia echinoptera Müller, 1840.

Other included taxa (3). Comactinia meridionalis L. Agassiz, 1865; Comactinia meridionalis hartlaubi Messing, 1978; Comactinia titan Messing, 2003.

Diagnosis. Mouth excentric in fully developed individuals; ten arms only, with anterior arms usually longer than posterior; centrodorsal circular, small and thin with cirri always present; IBr2 series united by synarthry; first syzygy at 3+4 on arms arising from IBr; distal intersyzygial interval irregular, 2–10; comb teeth either confluent, with tip truncated or notched and not tapering distally (Comactinia echinoptera), or nonconfluent and tapering to a blunt or sharp point (Comactinia meridionalis and C. titan).

Distribution. New Caledonia, Indonesia, and the Philippines (Comactinia titan), and western Atlantic from Cape Lookout, North Carolina, and the Gulf of Mexico to at least Cabo Frio, Brazil. Depth range: 15–373 m (possibly to 549 m). Only Comactinia meridionalis hartlaubi is chiefly collected below 100 m (AH Clark 1931; Messing 1978).

Remarks. Comactinia may be the only genus of Comatulidae distributed in both western Atlantic (C. echinoptera and C. meridionalis) and Indo-western Pacific waters (C. titan) (see Comissia venustus below). Morphological characters that unite the genus are found in other genera as well: ten arms only, IBr2 united by synarthry, excentric mouth, and combs to P2–P4. The notched comb teeth of C. echinoptera are unique in the family. C. meridionalis, which includes a large, deeper-water subspecies (C. m. hartlaubi), is widely variable, occurs over a wide depth range, and may constitute multiple species. A single row of nonconfluent comb teeth distinguishes C. meridionalis from other Atlantic comatulids. This feature, combined with ten arms, separates Comactinia titan from Pacific comatulids. Comactinia titan was previously known only from New Caledonia and the Philippines (73–84 m). During this study, three specimens were collected from ~ 15 m in Raja Ampat, Indonesia. For further discussion of this genus, see Messing (1978, 2003).

CAPILLASTERINI AH Clark, 1909d