Scolelepis (Scolelepis)

Götting, Miriam, 2015, Spionidae (Annelida: ‘ Polychaeta’: Canalipalpata) from Lizard Island, Great Barrier Reef, Australia: the genera Malacoceros, Scolelepis, Spio, Microspio, and Spiophanes, Zootaxa 4019 (1), pp. 378-413 : 392-394

Scolelepis (Scolelepis) sp.

Material examined. AM W.45019, MI QLD 2441, af, formalin.

Comparative material examined. Holotype of Scolelepis (Scolelepis) balihaiensis Hartmann-Schröder, 1979 , ZMH P15527, S Pacific Ocean, Western Australia, Broome, near Bali Hai, from encrustation of rock crevices in rock pools, 23 Sep 1975. Holotype of Scolelepis (Scolelepis) brevibranchia Hartmann-Schröder, 1991b , ZMH P20219, S Pacific Ocean, S Chile, Bahia Quillaipe, eulittoral, mud, af. Holotype of Scolelepis carunculata Blake & Kudenov, 1978 , NMV G2992, S Pacific Ocean, Victoria, Storeham, Westernport Bay, Station V47, 20 Dec 1965, almost complete.

Description. Notes on a single specimen: Anterior fragment of 33 chaetigers, 1.1 mm wide, 10.4 mm long. Prostomium anteriorly slightly truncated, posteriorly pointed with unattached caruncle; two pairs of minute black eyes in trapezoid arrangement located where prostomium is extended into a caruncle, anterior pair further apart; palps missing. Peristomium well developed forming low lateral wings partially encompassing prostomium posteriorly.

Chaetiger 1 reduced, with small elongate notopodial lamellae and larger rounded neuropodial lamellae; notochaetae absent. Branchiae from chaetiger 2, present throughout length of fragment. Notopodial lamellae folded, lower portion rounded; from chaetiger 2 distally free from branchiae; first branchiae and notopodial lamellae about the same length but from chaetiger 13–18 branchiae increasingly longer than notopodial lamellae and separation becoming more conspicous; from about chaetiger 24 branchiae and notopodial lamellae again shorter, separated distally, notopodial lamellae foliate and folded. Prechaetal notopodial lamellae small, rounded, most conspicuous from chaetigers 13–18. Neuropodial postchaetal lamellae rounded anteriorly, from chaetiger 18 slightly notched, becoming divided into large rounded neuropodial lamellae and small conical ventral (or subpodial) lobe, neuropodial lamellae foliate and in almost interramal position from chaetiger 20.

Anterior chaetae all capillaries without or with very narrow sheath; arranged in two rows in both rami, capillaries in anterior row slightly shorter, with very fine inconspicuous granulations near tip, capillaries in posterior row smooth. From chaetiger 20 neuropodial hooded hooks present, hooks bidentate with rudimentary apical tooth surmounting main fang, hooks numbering up to ten per fascicle, accompanied by few thin smooth alimbate capillaries anteriorly to the hooks; notochaetae smooth capillaries with very narrow sheaths, arranged in two rows with anterior chaetae distinctly shorter than posterior ones; notopodial hooks absent in examined specimen (af). Inferior capillaries in position of sabre chaetae in anterior and middle chaetigers, in hook-bearing chaetigers 1–2 granulated sabre chaetae with narrow sheaths present.

Pygidium not present in fragmented specimen from Lizard Island.

Pigmentation. Colour of formalin fixed specimen white without any pigmentation.

Methyl green staining pattern. Inconspicuous. Posterior unattached tip of the caruncle, branchiae and postchaetal lamellae most intensely stained.

Remarks. The incomplete specimen from Lizard Island could not be assigned to any known species of Scolelepis . The fragment is rather short and thus important characters could not be examined. For this reason a species name has not been assigned.

The specimen is similar to S. phyllobranchia Blake & Kudenov, 1978 in that the notochaetae are lacking in the first chaetiger, the prostomium is anteriorly slightly truncated, and in the presence of bidentate hooded hooks from about chaetiger 20 or 23, respectively. There are also several differences: the posterior part of the prostomium of S. phyllobranchia is described as elevated mound with small apical papilla whereas the specimen from Lizard Island is posteriorly pointed with an unattached caruncle. The branchiae and notopodial prechaetal lamellae of anterior chaetigers were observed to be totally fused in S. phyllobranchia whereas the branchial tips are separated from the postchaetal lamellae in the Lizard Island specimen. The typical stalks on posterior chaetigers from which separate notopodial lamellae and branchiae branch in S. phyllobranchia could not unambiguously identified in our specimen though the development of leaf-like lamellae and branchiae in posterior chaetigers of the incomplete specimen (chaetiger 33 being the last chaetiger) could be observed.

The lack of notochaetae in the first chaetiger together with a posteriorly pointed prostomium is also shared with following species of the genus Scolelepis (Scolelepis) from the Pacific and Indian Oceans: S. carrascoi ( Maciolek, 1987) , S. bullibranchia Rossi, 1982 , S. dicha Hutchings, Frouin & Hily, 1998 , S. laciniata Eibye- Jacobson, 1997, S. oligobranchia (Khlebovitch, 1959) , S. planata Imajima, 1992 , S. towra Blake & Kudenov, 1978 , S. vexillatus ( Hutchings & Rainer, 1979) , and S. williami (de Silva, 1961). However, all species have characters which separate them from our specimen. S. bullibranchia has tridentate hooks and branchiae with darkened glandular inclusions. In S. dicha , S. williami and S. laciniata notopodial lamellae and branchiae are only basally fused and the branchiae are much longer than the notopodial lamellae whereas in our specimens only the tips of branchiae are free and the length of branchiae and folded notopodial lamellae is not very different. In contrast, S. oligobranchia , S. towra and S. vexillatus have branchiae which are completely fused to notopodial prechaetal lamellae in anterior chaetigers. S. planata can be distinguished because its caruncle is flattened with distal point rather than being pointed and unattached. Also, neuropodial hooks are multidentate in S. planata , S. towra , and S. carrascoi instead of being bidentate.

Another species described lacking notochaetae on the first chaetiger and having a posteriorly pointed prostomium is Scolelepis balihaiensis Hartmann-Schröder, 1979 from Western Australia. Examination of the holotype revealed that notochaetae are present instead of absent in the first chaetiger (although partially hidden by the palps). Also, the information is added to the original description that the caruncle is not attached in the holotype. S. balihaiensis is morphologically very similar to S. carunculata Blake & Kudenov, 1978 but S.

carunculata has only unidentate or bidentate hooks in posterior notopodia whereas S. balihaiensis has tridentate hooks in the notopodia.

Habitat / Ecology. The species was found in sandy mud with filamentous algae in 15 m water depth. Distribution. The single specimen, an anterior fragment, was found NW of Watson's Bay in the Lizard Island area, Queensland.