Amphilepis neozelandica Mills & O'Hara, 2010, sp. nov.

• Main Authors: Mills, Sadie, O'Hara, Timothy
• Format: Text
• Language: unknown
• Published: Zenodo 2010
• Subjects: Biodiversity; Taxonomy; Animalia; Echinodermata; Ophiuroidea; Ophiurida; Amphilepididae; Amphilepis; Amphilepis neozelandica; Middle Arm; New Zealand; Paterson; North Atlantic
• Online Access: https://dx.doi.org/10.5281/zenodo.6201228; https://zenodo.org/record/6201228

Amphilepis neozelandica sp. nov. (Figs 1, 2) Material examined. Holotype: NIWA 41902, northern slope of Chatham Rise, 42 ° 32.34 ˏS, 178 ° 20.29 ˏW, to 42 ° 32.60 ˏS, 178 ° 20.39 ˏW, 1404–1414 m, TAN0705/203, 20 April 2007. Paratypes: NIWA 41877, 1 specimen, NE Chatham Rise, 43 °04.42ˏS, 174 ° 56.09 ˏW to 43 °03.93ˏS, 174 ° 56.01 ˏW, 930–934 m, TAN0705/126, 13 April 2007; NIWA 41957, 1 specimen, northern edge of Challenger Plateau, 37 ° 29.24 ˏS, 169 ° 27.63 ˏE to 37 ° 29.76 ˏS, 169 ° 27.672 ˏE, 1152–1153 m, TAN0707/10, 27 May 2007; NIWA 45925, 1 specimen, Wairarapa South Tower, 41 ° 47.388 ˏS, 175 ° 24.288 ˏE to 41 ° 47.268 ˏS, 175 ° 24.528 ˏE, 1053 – 1050 m, TAN0616/81, 13 November 2006. Description of holotype: (Figs 1, 2 A, B, E) Disc diameter 7.3 mm, round, covered with large, regularly arranged, thin, rounded, very flat, overlapping scales. Peripheral scales one layer thick and overlapping disc margin, giving disc edge a sharp appearance. Primary plates obvious, of roughly equal size (0.6 mm) and surrounded by smaller plates. Radial shield fan-triangular to elongated trapezoid in shape, 1 / 5 d.d. in length, and form part of the edge of the disc. Shields divergent, with straight internal (adradial) edge, slightly curved external (abradial) edge, completely separated by wedge of 2 elongated disc scales. Ventral interradial area with smaller, unequal and imbricating scales, thinning to single layer at disc margin, enhancing sharp appearance of disc. [Disc of holotype punctured by echinoid spine, leaving small circular hole in ventral disc]. Bursal slit absent; paired genital scales present along each side of arms, narrow, partially obscured, approximately 1.5 mm long. Scales: A = 2 mm; B–H = 1 mm Oral shields rounded, triangular, wider than long, narrowly in contact with first lateral arm plate at distal margin. One larger oral shield bears the madreporite. Adoral shields broadly in contact proximally, flared distally around edges of first ventral arm plates. Jaw with single apical papilla and 2 laterally positioned oral papillae on each jaw angle. Distal papillae rectangular, broad, low, 3–4 times wider than long, proximal corner pointed. Proximal papillae conical-triangular, about as wide as long, sharply pointed. Apical papilla triangular, sharply pointed, present on 3 jaws; remaining 2 jaws with ventral-most tooth square with pointed median cusp, visible through gap between somewhat infradentally placed proximal papillae; 3 dorsal-most teeth squarer, with median point. Pore of second oral tentacle opening outside mouth between first ventral arm plate and oral plates, without tentacle scale. Arms dorsoventrally flattened, incomplete in holotype, 1.3 mm wide at arm base. [A detached arm fragment approximately 19 mm long; gradually tapering to 0.7 mm wide at arm tip]. Dorsal arm plates separate, transverse oval, twice as wide as long. First ventral arm plate smaller than successive plates, pentagonal with flat proximal margin; successive ventral arm plates pentagonal, slightly wider than long, distal margin rounded, proximal margin acute. Ventral arm plates laterally incised by large tentacle pores; separated by lateral arm plates from first segment onwards. Each lateral arm plate bearing 3 bluntly pointed arm spines. First arm segment with single spine, second and third segments with 2 spines, then 3 spines from 4 th segment onwards. Dorsal-most spine shortest (0.4 mm at disc edge), remaining slightly shorter than one arm segment. Ventralmost and middle arm spines slightly longer than one arm segment, length subequal (0.7 mm), thickness subequal (0.1 mm at base of spine). Every arm segment with large, open tentacle pores. Tentacle scales absent. Paratypes: (Figs 2 C, D, F–H) Disc diameter 6.0– 7.4 mm. Arms incomplete on all specimens; however, detached arms measure 19–33 mm in length, tapering from 1.3 mm in width at the base to 0.3 mm at the tip. There are slight variations in the disc scaling between the smallest paratype (NIWA 41957, 6 mm d.d., Fig. 2 H), in which the scales are thinner with less vertical relief, and in the largest paratype (NIWA 45925, 7.4 mm d.d., Fig. 2 F) where the edge of the scales are more defined and slightly more hexagonal. The oral papillae appear to be variable both within and between specimens; NIWA 41957 has triangular apical papillae on all jaws, though one is damaged and appears blunt; NIWA 45925 has an apical papilla on only two of its jaws, revealing broad cusped teeth similar to the holotype; The papillae in NIWA 41877 appear to be sometimes bicuspate, with 2 oral papillae on some jaw surfaces, and 3 on others where one of the oral papillae has split. Genital scales can be seen clearly in the paratypes, particularly in NIWA 45925 where one arm has become detached above these plates. The narrow paired scales lie parallel to the arms, with a long adradial scale (1.7 mm) and a shorter abradial scale (figure 2 D). The shape of the internal oral and dental plates are not described here; the paucity of material precluding dissection. Colour (preserved in ethanol): Holotype and two paratypes pale off-white, with darker cream radial shields and tube feet. Paratype, NIWA 45925, pale yellow on dorsal and ventral disc, with darker yelloworange radial shields, primary plates and arms. Arm spines bright white. Etymology: Named neozelandica for the geographical distribution of the species, and as the first record of the family in New Zealand. Distribution: (Fig. 3) Chatham Rise, Challenger Plateau and off the Wairarapa Coast, New Zealand. 980– 1414 m. Remarks. This species is referable to Amphilepis on the basis of the second tentacle pore opening outside the mouth, the absence of genital bursae and clefts, and the conspicuous radial shields (Fell 1960). The superficial apical papilla (or ventral-most tooth) and an elongate oral tentacle scale (sometimes broken into 2 or 3 pieces) characteristic of this genus, both of which are confluent with the pointed inner oral papilla, are present in these specimens (Clark 1970). Amphilepis neozelandica can be distinguished from the majority of congeners by the combination of absence of tentacle scales, full ventral interradial scaling, and dorsal and ventral arm plates that are separate from each other at the first arm segment. The species most similar to A. neozelandica are A. ingolfiana Mortensen, 1933 a and A. norvegica (Ljungman, 1865). Mortensen (1933 a) remarks that A. ingolfiana can be distinguished from A. norvegica by the genital scales, which in A. ingolfiana has a shorter abradial branch and a longer adradial branch, and in the shape of the radial shields, which are more rounded on their abradial edge. The genital scales of A. neozelandica agree with those of A. ingolfiana (Fig. 2 D) as do the radial shields, effectively separating it from A. norvegica . The round disc shape of A. neozelandica separates it from A. ingolfiana , which has a distinctly pentagonal disc, though they share a sharp appearance to the disc edge and the shape of the radial shields (Stöhr, pers. comm .). The adoral shields of A. ingolfiana are expanded distally, with an acute distolateral angle compared to those of A. neozelandica which are rounded where they flare around the edge of the first ventral armplate (Mortensen 1933 a; Paterson 1985). Juvenile specimens of A. ingolfiana less than 3 mm d.d. are recorded as having a small spine on the adoral shield, which is lost in larger specimens (Mortensen 1933 a). This has not yet been observed in A. neozelandica , and more material is needed to verify whether this feature is present in smaller specimens. Amphilepis ingolfiana is a deepwater species (957–4829 m) and is widespread in the northern Atlantic Ocean. Despite the geographical separation between these species, A. neozelandica and A. ingolfiana are morphologically similar. Small variations in the appearance of A. neozelandica between paratypes (Fig. 2) from the holotype may be related to age or polymorphism. However, this can not be properly evaluated with only one specimen per geographic location. More material is required to determine whether more than one species of Amphilepis exists in New Zealand waters. : Published as part of Mills, Sadie & O'Hara, Timothy, 2010, Amphilepis neozelandica sp. nov., the first record of the Amphilepididae in New Zealand waters (Echinodermata: Ophiuroidea), pp. 47-54 in Zootaxa 2514 on pages 48-52, DOI: 10.5281/zenodo.196098 : {"references": ["Fell, H. B. (1960) Synoptic keys to the genera of Ophiuroidea. Zoological publications of the Victoria University of Wellington, 26, 1 - 44.", "Clark, A. M. (1970) Notes on the family Amphiuridae (Ophiuroidea). Bulletin of the British Museum of Natural History, 19, 1 - 81.", "Mortensen, T. (1933 a) Ophiuroidea. Danish Ingolf Expedition, 4 (8), 1 - 121, 3 pls.", "Ljungman, A. V. (1865) Tillagg till kannedom af Skandinaviens Ophiurider. Ofversigt af Kongl. Vetenskaps-Akademiens Forhandlingar, Stockholm 1863, 7, 359 - 370.", "Paterson, G. L. J. (1985) The deep-sea Ophiuroidea of the North Atlantic Ocean. Bulletin of the British Museum (Natural History), 49, 1 - 162."]}