Synelmis albini ( Langerhans, 1881 )

Glasby, Christopher J., 2003, A new species of Synelmis (Annelida, Polychaeta, Pilargidae) from New Zealand and designation of a neotype for S. albini from the Canary Islands, Zoosystema 25 (1), pp. 7-15 : 9-12

Synelmis albini ( Langerhans, 1881)

( Fig. 1 )

Ancistrosyllis albini Langerhans, 1881: 107 , 108, fig. 16a-d.

Synelmis albini – Núñez et al. 1984: 128 [list]. — Núñez 1991: 251-253. — Brito et al. 1996: 159, 160, fig. 8A-F.

MATERIAL EXAMINED. — Canary Islands . Tenerife, Playa de la Tejita, mesolitoral, algas, 4.IV.1976, coll. J. Núñez No. PO-183-88, neotype by present designation (TFMC-BMAN/000214) ; 1 specimen (Núñez personal collection).

TYPE LOCALITY. — Tenerife, Playa de la Tejita (determined by neotype).

DISTRIBUTION. — Known with certainty only from shallow subtidal rocky reefs of Tenerife and Fuerteventura, Canary Islands.

DESCRIPTION

Neotype complete, but broken into two halves; combined length 15.0 mm, 0.6 mm wide (without parapodia) and 0.7 mm (with parapodia); 63 chaetigers.

Body translucent, metallic sheen, creamy white except for reddish glandular dorsal and ventral cirri and subcutaneous reddish pigment on venter of posterior half of body either side of the midline. Body slender, arched dorsally, flatter ventrally (shape somewhat distorted), weak midventral groove discernible ( Fig. 1A, B ).

Prostomium ill-defined, wider than long, slight mid-dorsal depression ( Fig. 1A ). Lateral antennae short, cirriform, much less than prostomium length, inserted at lateral base of palps; median antenna similar to laterals, arising from posterior edge of prostomium ( Fig. 1A ). One pair lateral eyespots on posterolateral prostomium, faded and barely visible. Palps large, weakly biarticulate; palpostyle globular, not clearly demarcated from palpophore (palps in extended state). Short palpal papilla arising from ventrolateral junction of palpophore and palpostyle, not extending beyond palpostyle. Hindbrain not clearly visible through body wall. Pharynx partially everted, muscle bands of posterior portion visible through body wall, extending posteriorly to about chaetiger 6 ( Fig. 1A ); thereafter muscular oesophagus extends posteriorly to about chaetigers 16-17, where intestine begins.

Tentacular cirri weakly fusiform, similar in size to corresponding cirri on first chaetiger. Parapodia with fusiform dorsal and ventral cirri, broadening slightly and becoming strongly fusiform with acuminate tips posteriorly; dorsal cirri about one and a half times larger than ventral cirri throughout ( Fig. 1 C-E). Chaetal lobe subconical, slightly smaller than dorsal cirrus anteriorly, decreasing in relative size posteriorly. Notopodial spines clear, straight and tapering to a rounded tip ( Fig. 1F ), present in every parapodium from chaetiger 10, only one spine per notopodium, slightly emergent at dorsal base of dorsal cirrus; thicker than notoacicula over entire body. Neurochaetae of three types in each parapodium: a few long limbate chaetae with faintly serrated wing (visible under 63 × obj.) ( Fig. 1G ); one or two shorter capillaries ( Fig. 1H ); and one to three very short furcate chaetae with tines of similar thickness but distinctly different lengths ( Fig. 1I ). A single notoacicula per parapodium. Neuroaciculae not visible in anterior parapodia, but discernable posteriorly ( Fig. 1E ).

Pre-pygidial region comprising three segments with very small cirri, lacking chaetal lobes and chaetae ( Fig. 1B ). Pygidium bearing pair of short cirriform anal cirri.

Variation

Other specimen collected at the same time and place as the neotype complete, 16.5 mm long, 0.5 mm wide (without parapodia), 0.6 mm (with parapodia) at chaetiger 10; 70 chaetigers. Both mid-ventral groove and lateral grooves (in line of parapodia) present. Eyes absent, probably faded. Pharynx fully everted, visible through body wall, extending posteriorly to about chaetiger 4; thereafter muscular oesophagus extends posteriorly to about chaetiger 14. Notopodial spines from chaetiger 9.

REMARKS

Langerhans’ type material originally housed in the Science Museum (Freiburg, Germany) was destroyed during the World War II according to Brito et al. (1996). They re-described Synelmis albini based on five specimens from the Canary Islands; two were the specimens studied here from Tenerife, and the other three were specimens from Majanicho, Fuerteventura. The same five specimens were described earlier in the unpublished thesis of Jorge Núñez ( Núñez 1991), and in the same work the Majanicho specimens were identified as potential neotypes. Subsequently, the three Majanicho specimens were registered as “neotipos” with the Museo de Ciencias Naturales (Santa Cruz de Tenerife, Tenerife) (TFMC-AN/0178) (Brito et al. 1996). However, this must be regarded as an invalid neotype designation (irrespective of whether or not the thesis satisfies the ICZN as a valid publication) because among other reasons it was not accompanied by a statement identifying a particular specimen as the neotype and the specimens were not from near the original type locality, the rocky coast of Puerto de la Orotava, northern Tenerife (see Langerhans 1881: 95).

In order to rectify the situation, one of the two specimens described here from Playa de la Tejita, Tenerife, is here designated as the neotype, and a new registration number (TFMC- BMAN/000214) applied. The previous number (TFMC-AN/0178) has been cancelled (F. Hernández Martín pers. comm.). The neotype designated here is topotypic and is consistent with what is known about the former name-bearing type according to Langerhans (1881) and the descriptions of Núñez (1991) and Brito et al. (1996). The only discrepancies between Núñez (1991) and Brito et al. (1996) and the present description can be attributed to the larger body size (their largest specimen measured 20 mm in length, 0.5 mm wide and 110 chaetigers), and the slightly better condition of the Fuerteventura specimens. A pair of eyes is obvious in the Fuerteventura specimens, lateral antennae arise anterolaterally on the prostomium (the mid-lateral position on the present material is probably the result of distortion of the prostomium as a result of the eversion of the pharynx); notopodia have one or two notoaciculae whereas I observed only a single notoacicula.

A

B

Brito et al. (1996) describe the notopodial spines as starting anywhere between chaetigers 5 to 20, but this most likely is based not only on observations made from their specimens, but also on Pettibone (1966), who held a wide view of the species. Notopodial spines in the Playa de la Tejita specimens are present from chaetigers 9 or 10. Langerhans (1881) states that the notopodial spines begin on segment 7 (= chaetiger 6) and that they gradually become thicker and are prominent by segment 12. Therefore, until further material can be examined, S. albini is considered to have notopodial spines beginning from chaetigers 5-10. This narrower range in the starting point of the notopodial spines is in keeping with the findings of Salazar-Vallejo (2003), especially for species in which the spines start early.

An interesting feature recorded by Langerhans (1881: fig. 16d) for S. albini , but not reported by other authors, is the presence of a ring or halo of fine hairs (= fimbriae), which are visible when the pharynx is everted. The fimbriae resemble those of certain hesionids. The fimbriae were not seen in the Tenerife specimens, probably because the degree of pharyngeal eversion was insufficient. However, fimbriae were observed in the new species of Synelmis from New Zealand. The generality of the presence of pharyngeal fimbriae in Synelmis (and other pilargids) is worthy of further investigation especially in regard to the phylogeny of the group.

Figures

FIG. 1. — Synelmis albini (Langerhans, 1881), neotype (TFMC-BMAN/000214); A, anterior end, dorsal view, pharynx partially evert- ed, right side parapodium 5 removed; B, posterior end, dorsal view; C, parapodium from chaetiger 9, left side, posterior view (one capillary chaeta broken); D, parapodium from chaetiger 31, right side, posterior view; E, parapodium from chaetiger 52, left side, posterior view (one capillary chaeta broken); F, notopodial spine from parapodia of chaetiger 31; G, H, two types of capillaries from parapodia of chaetiger 31; I, furcate chaeta from parapodia of chaetiger 52. Scale bars: A, B, 0.25 mm; C-E, 0.05 mm; F-I, 0.02 mm.