A NEW SPECIES OF PATIR1ELLA 



131 



regularis together with P. gunni (Gray) and P. calcar (Lamarck) 

 from Australia, also P. exigua (Lamarck) which extends from the 

 Indo-West Pacific into the S.E. Atlantic'. She thought reassessment 

 of the rank of Patiriella was best left to 'one of several Australasian 

 specialists to determine . . .', retaining the species exigua as a mem- 

 ber of the genus Patiriella. A new review of the family Asterinidae, 

 including a reappraisal of the status of Patiriella is being undertaken 

 by F.W.E.R. elsewhere. However, whilst in the present paper we 

 acknowledge that a very close relationship exists between the genera 

 Asterina, Patiriella and Patiria (Gray, 1840) (Patiria is considered a 

 synonym of Asterina by Hayashi (1940) and A.M. Clark (1983 (in 

 Clark and Downey, 1992)); we accept their separate generic status, 

 until the matter is more clearly resolved, such a resolution being 

 outside the scope of this paper '. In taking this stance, we have 

 amended A.M. Clark's in Clark and Downey, 1992) diagnosis of 

 Patiriella to include a description of the alignment of actinal plates 

 (included by Verrill (1913) in his diagnosis of the genus) and the 

 internal alignment of actinal/abactinal plates at the ventral/lateral 

 angle (described by Verrill (1913) as a feature of the family 

 Asterinidae). As a taxonomic character, actinal plate alignment has 

 been largely ignored. The exception was Fisher (1917; 1919) who 

 thought this a useful character when distinguishing his new genus 

 Paranepanthia (type-species Nepanthia platydisca Fisher, 1913) in 

 which the plates are aligned obliquely across the actinal surface, 

 from Asterina in which he saw the actinal plates forming chevrons 

 across each interradial area, the plates being aligned only parallel to 

 the furrows along each ray. Fisher (1919) was, however, comparing 

 Paranepanthia platydisca with the species 'Asterina' cepheus (Miiller 

 & Troschel), and VT. coronata (von Martens) and not the type 

 species A.gibbosa. In accepting Asterina in this sense, Fisher was 

 clearly not familiar with the fact that in the type-species, A. gibbosa, 

 the actinal plates, as in Patiriella and Paranepanthia, are clearly 

 aligned obliquely between furrow and margin Fig 1 a & b (there is no 

 question, however, that Paranepanthia is a valid genus (F.W.E.R.). 

 A.M. Clark (1971, in A.M. Clark and Rowe) noted Fisher's work 

 when identifying two specimens of an undetermined species of what 

 she considered a Paranepanthia from Zanzibar. She considered 

 (1971:71) the importance of actinal plate arrangement, as a func- 

 tional and taxonomic character, required investigation. However, 

 A.M. Clark ( 1983) did not expand further on this matter in her more 

 recent revision of the family Asterinidae. Although a recent survey 

 of the family by one of us (F.W.E.R.) does show actinal plate 

 arrangement to be a useful character in distinguishing some of the 

 genera, actinal plate arrangement undoubtedly has a functional role 

 which is probably micro-habitat related. We include description of 

 the internal structure of the ventral/lateral angle in our diagnosis 

 following A.M. Clark (1983) who concluded that differences in 

 arrangement of these internal plates were important in indicating 

 taxonomic affinities, a conclusion supported herein, though on the 

 basis also, that it may relate to ray shape within the family. 



Patiriella paradoxa sp. nov. 



DIAGNOSIS. Stellate species of Patiriella with five rays; abactinal 

 plates of aboral, radial 'field' tri-quadrilobed, forming a delicate 

 reticulum; papular areas each with three to six papulae and one to 

 two secondary plates; no suboral spines; proximal actinal plates 

 each with a single spine. 



1 Species attributed to Asterina s.s. from outside the Atlantic region are NOT conge- 

 neric with the type-species. A. gibbosa (Pennant), and require reallocation to other 

 existing or new asterinid genera according to Rowe (in Rowe and Gates, 1995); the 

 suggested recognition of Asterinides Verrill (1913) (type-species A. folium (Lutken)) as 

 a valid subgenus of Asterina, by A.M. Clark (1983; 1992 (in Clark and Downey)) is 

 supported, but at generic level, by Rowe (in Rowe and Gates, 1995). 



HOLOTYPE. BMNH (dry) BMNH 1997.1016 



Type LOCALITY. 0.5 km southeast of Wadi Haart and about 4km 

 north east of Sadh village, Sultanate of Oman (17° 04'N, 55° 06E), 

 intertidal, just below level of the conspicuous barnacle Tetraclita 

 squamosa rufotincta, collected together with 'Asterina' cepheus 

 (Muller& Troschel, 1842), A.C.Campbell 4 May 1987(210050201) 

 (fig-2). 



Material. In addition to the holotype, two paratypes (dry). 

 Paratype 1 BMNH 1997. 1017, collected at the same locality with the 

 holotype. Paratype 2 BMNH 1997.1018, Raaha, 2.5km west of Wadi 

 Ayn, Sultanate of Oman (16° 58'N, 54° 50'E), c. 8m depth, on rocks 

 amongst corals, coll. A.C. Campbell, 5 Dec, 1986 (210050202) 

 (fig.2). 



EtYMOLOGY. The species name (Lat. paradoxum) refers to the 

 unexpected occurrence of this predominently temperate-water ge- 

 nus along an otherwise tropical coastline. 



Description of holotype. (Figs 3 a & b; 4 a & b). Specimen 

 stellate in outline, R=l 7.8mm, r=9.0mm, R/r=1.98; br=10.3mm 

 (across base of ray between first superomarginal on each side), R/ 

 br=l .73. Orally flat, aborally arched. Rays more or less elongate 

 triangular, tapering from a relatively wide base to a rounded tip. 

 Centre of disc delimited by a complete ring of prominent, spinelet- 

 bearing plates, outside of which a second, more or less complete ring 

 of less prominent plates evident. The prominent, ovate madreporite 

 occurs in interradius CD. 



Beyond the central disc, the imbricating primary abactinal plates 

 form two 'fields' along the rays. Radial 'field' comprising an 

 irregular, zig-zag series of mid-radial (carinal) plates and the first 

 dorsal-lateral row on each side. Shape of this 'field' elongate-leaf- 

 shaped along the ray, tapering proximally and distally and widest 

 at about '/2R. Denuded plates deeply notched, mostly quadrilobed 

 (X-shaped), but, at least between '/2-%R, some mid-radial plates 

 tri-lobed (Y-shaped), the plates together forming a relatively deli- 

 cate reticulum. Papular areas, between the plates, are relatively 

 large, up to 0.8mm diameter, each subtending 3-6 papulae 

 between which 1 or 2 minute, spinelet-bearing secondary plates 

 usually occur. Primary plates with crystal bodies, except on their 

 proximal, crescentic ridge which carries 5-7 granuliform spinelets 

 in a single series; spinelets range from c. 0.30mm long x 0.12mm 

 wide (straight sided) to about 0.37mm long x 0. 14mm wide (these 

 larger spinelets becoming club-shaped (0.18mm wide) towards 

 their tip). Lateral 'field' comprising about 10 regularly arranged 

 rows of plates at the base of the rays, closely imbricate with a deep 

 proximal notch subtending 1-3 papulae occurring in the proximal 

 half of the first 5 rows of plates, the papulae not extending to the 

 superomarginal line. Lateral 'field' plates with crystal bodies and 

 from 2-7 spinelets. 



Ventral-lateral margin sharply delimited, however neither 

 inferomarginals nor superomarginals significantly larger than im- 

 mediately adjacent actinal or abactinal plates respectively. Infero- 

 marginal plates aligned in the same plane as the actinal surface, 

 slightly protrude laterally and bear a group of 2-3 minute spinelets. 

 Superomarginal plates aligned vertically, correspond with the 

 inferomarginals below them and bear 1-2 spinelets. 



About 10 rows of actinal plates counted; the first two extending to 

 the tip of the ray; plates are aligned both parallel to the furrow but 

 also distinctly obliquely across the actinal surface between the 

 adambulacral plates and inferomarginal plates. Oblique alignment 

 accentuated both by the actinal spination and narrow, shallow 



