Ophiozonella projecta ( Koehler, 1905 )

Stöhr, Sabine, 2011, New records and new species of Ophiuroidea (Echinodermata) from Lifou, Loyalty Islands, New Caledonia, Zootaxa 3089, pp. 1-50 : 40-42

Ophiozonella projecta ( Koehler, 1905)

Figure 19

Material. Sta. 1461: 2 spms; sta. DW1648: 1 spm; sta. DW1650C: 7 spms.

Comparative material. Syntypes (as Ophiozona projecta ), Siboga sta. 96, Philippines, Sulu Archipel, SE of “Perlbank”, 15 m, [ ZMA U.Ech O. 2569] and Siboga sta. 142, Obi Major ( Moluccas), Mouiallge de Laiwu, 23 m, [ ZMA U.Ech O. 2570]. Ophiozonella longispina ( H.L. Clark, 1908) , Vega Expedition 1878-80, Japan, Honshu, Yeddo bay, 119 m, 11.10.1879 [SMNH-108072].

Remarks. The Lifou specimens agree well with the syntypes. The colouration is light brown and preserves well in alcohol. They are characterized by tuberculous, more or less convex, dorsal disk plates, a distinct trio of plates distal to the radial shields and three small, blunt arm spines, of which the ventralmost one is distinctly larger than the other two. The microstructure of the arm plates shows a grainy surface. The proximal arm vertebrae are elongated, similar to distal vertebrae of O. longispina , suggesting a paedomorphic condition in O. projecta . The spine articulation consists of two narrow parallel ribs and differs from the thicker, rounded, at one end connected ribs that comprise the articulation of O. longispina ; another possible indication of paedomorphosis. In placing this species in Ophiozonella, Matsumoto (1915) contradicts himself immediately after describing the genus as lacking the trio of plates distal to the radial shields (typical for Ophiolepis ), since these are obvious in the syntypes. The validity of this character is thus doubtful. Ophiolepis is also differentiated from Ophiozonella by its larger dorsal disk plates being encircled by small scales. However, in juvenile Ophiolepis superba H.L. Clark, 1915 (the generic type) these scales are absent (Cherbonnier & Guille 1978). The partially paedomorphic appearance of the small species O. projecta , the presence of a trio of plates distal to the radial shields, and its occurrence at rather shallow depths suggest that the affinities between Ophiozonella and Ophiolepis may need to be re-investigated. The species may also be mistaken for an Ophiozonoida (see above), further emphasizing the need for taxonomic revision of all these forms.

Distribution. The species has a wide distribution, from Japan to the Philippines and New Caledonia, for which it is a new record. The four syntype localities in the original description ( Koehler 1905) range across depths of 15– 113 m, whereas the specimens from Lifou were collected at depths of 100– 260 m.

Figures

FIGURE 19. SEM images, A – J, Ophiozonella projecta. A, dorsal aspect; B, dorsal arm, note the triplet of plates at the arm base; C, ventral aspect; D, ventrolateral arm; E, arm spine, articulating end; F, spine articulation on lateral arm plate; G, proximal vertebra, proximal face; H, proximal vertebra, lateral aspect; I, proximal vertebra, distal face; J, proximal lateral arm plate, internal aspect. K – L, Ophiozonella longispina. K, spine articulations on lateral arm plate; L, arm spine, articulating end; M, distal vertebra, lateral aspect. Scale bars in millimetre.