Spurilla Bergh, 1864

Miller, M. C., 2001, Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Aeolidiidae from New Zealand waters, Journal of Natural History 35 (5), pp. 629-662 : 640-641

Genus Spurilla Bergh, 1864

Spurilla Bergh, 1864: 67 ; Bergh, 1876: 758; Bergh, 1892: 1020; MacFarland, 1909: 88 ±89;

VayssieÁre, 1913: 300±301; Engel, 1925: 14 ±17; Pruvot-Fol, 1954: 432±33; Marcus, 1955:

184±187; Schmekel and Portmann, 1982: 224.

Diagnosis

Body moderately wide, tapering very gradually, i.e., appears almost straightsided except at the tail end, pericardial swelling prominent, oral tentacles and rhinophores shortish, latter lamellate, lamellae many de®nite or few inde®nite, transverse or oblique; cerata cylindrical, tips curving over at least in the type species, slightly compressed, arranged in arches on low swellings, rows single or becoming double towards tips of arch (in ®rst two arches); cleioproctic, anus within second ceratal arch but position varies, renal pore ad- or abanal (in latter it may lie in front of the arch), reproductive apertures immediately below and outside ®rst arch; foot expanded anteriorly as blunt angles or short tentacular processes; oral gland composite, large, tubular, tapering, one pair, occasionally more; radular teeth fairly wide, divided, denticles graded, small cusp; jaw masticatory process smooth.

Type species. (By monotypy) Eolis neapolitana Delle Chiaje, 1841 .

This genus was created by Bergh (1864) to separate Eolis neapolitana from the other aeolids (placed in the genus Aeolidia and variant spellings of this name; see Lemche, 1964a) with a pectinate radula known at that time. The distinguishing character at that time was the lamellate rhinophores. Later Trinchese (1877) created the genus Berghia for a species, Eolidia coerulescens Laurillard, 1830 , with nodulose rhinophores. Since then more species have been added to the genera Spurilla , Aeolidiella (previously Eolidina ) and Berghia , and, as a consequence, the de®ning feature, the ®ne structure of the rhinophores, has become less clear. This has led to the rede®nition of these genera (see Marcus, 1961; Burn, 1969; Rudman, 1982; Gosliner, 1985). Two other aeolidiid genera, Baeolidia and Limenandra , were involved in this rede®nition. Most extreme has been Rudman (1982) who united Spurilla , Berghia and Baeolidia . However, the type species of Spurilla is very recognizable on features other than the form of the rhinophoresÐthe almost straight-sided body, slightly ¯attened curled cerata on low arch-shaped pads, and the strands of digestive tissue (? and zooxanthellae) which spread well beyond the ceratal areaÐ the latter also occurring in Baeolidia major Eliot, 1903 , Spurilla australis Rudman, 1982 , and Aeolidiella japonica Eliot, 1913 . Other species which have been added to Spurilla do not possess all of these features, which are also markedly diOEerent in others, widening the de®nition of Spurilla . The same has happened to Berghia . Initially represented by just the type, Berghia coerulescens , Berghia was clearly distinguishable on the high tapered body, slightly swollen fusiform cerata and lack of extra-ductal digestive tissue. The variation contributed by the additional species has brought the genera Spurilla and Berghia closer together so that small diOEerences in rhinophoral ornamentation and ceratal shape seem to be all that separate them. Even so I still remain to be convinced that the approximation of the two genera is close enough to justify uniting them. Therefore, I maintain them here.

Unlike Rudman (1982), I would uphold the genus Baeolidia principally on the basis that the ceratal arrangement diOEers from that of Spurilla and Berghia in that the ceratal arches are tall, narrow and greatly bent towards the anterior end of the body, and the cerata are wide, curved in section and in a single row. Additionally, the body is wider, papillation is even and continuous around the rhinophoral club, the dorsal lip of the anterior foot groove is deeply cleft mesially, radular teeth a wide single bow without a recognizable cusp. Obviously my determination of Baeolidia diOEers from that of Gosliner (1985). This is explained later in the section on the genus Baeolidia .