Scolelepis (Scolelepis) kudenovi Hartmann-Schröder, 1981

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 : 390-392

Scolelepis (Scolelepis) kudenovi Hartmann-Schröder, 1981

( Fig. 4 )

Scolelepis (Scolelepis) kudenovi Hartmann-Schröder, 1981: 52 , figs 124–129.— Maciolek 1987: table 1; Imajima 1992: 17 –18, figs 11, 12.

Type material. Holotype: ZMH P16497, S. Pacific Ocean, Western Australia, Canarvon, Pelican point, inner beach, fine sand with detritus and Posidonia seedlings, 19.5 °C, 13 Oct 1975, af.

Other material examined. AM W.44836, MI QLD 2429, af, formalin; AM W.44836.001, mf, 96 % ethanol, no longer extant.

Diagnosis. Prostomium anteriorly trifid, median lobe sharply pointed, anterolateral lobes tapered; prostomium with transverse furrow in front of caruncle; caruncle subulate, slightly inflated, attached to dorsum. Low transversal ciliated bands present throughout the body. Chaetiger 1 well developed with chaetae in both rami. Branchial tips always free from notopodial postchaetal lamellae. Hooded hooks bidentate with very upright apical tooth in neuropodia from about chaetigers 38–44 (Australian specimens) or bidentate hooks from chaetigers 26–33 (Japanese specimens, Imajima 1992); in notopodia hooks from about chaetiger 98 (Australian holotype) or 55–62 (Japanese specimens). In Japanese specimens pygidium with ventral, entire cushion, unknown for Australian specimens.

Description. Based on re-examination of holotype and original description by Hartmann-Schröder (1981). Holotype fragmented specimen: one anterior fragment with nine chaetigers, three middle fragments of different length (66, 54, and 3 chaetigers); body width about 1 mm (measured at 8th chaetiger), total length of all fragments 42 mm. Prostomium anteriorly trifid, median lobe sharply pointed and considerably projecting over anterolateral lobes and peristomium, anterolateral lobes tapered but not pointed, only slightly projecting over peristomium; prostomium with transverse furrow at level of palpal insertion and beginning of chaetiger 1, beyond this furrow extended into subulate, slightly inflated caruncle reaching end of chaetiger 1, caruncle attached to dorsum ( Fig. 4 A). Palps rather thin and short, reaching back to about chaetiger 5, palpal base thickened. According to original description two pairs of eyes arranged in trapezoid, anterior pair smaller and further apart than posterior pair, both pairs close to each other almost forming one row (at the time of re-examination of the holotype no longer discernable). Peristomium moderately developed without forming wings. Low but distinct transversal ciliated bands (tcb´s) present throughout body.

Chaetiger 1 well developed, with subulate postchaetal lamellae in both rami, notopodial lamellae slightly longer and more slender than neuropodial lamellae; notochaetae present. Branchiae from chaetiger 2, present throughout length of fragment; anterior branchiae cirriform with rounded tip, not much longer than notopodial postchaetal lamellae of same chaetiger and fused to it at base; from chaetiger 8 branchiae elongate and pointed, distinctly longer than notopodial lamellae and fused to it except at its tip; from about chaetiger 40 branchiae continously decreasing in length until posterior body region, notopodial lamellae attached to basal part of branchiae. Notopodial lamellae in anterior chaetigers tapered, lower portion rounded, fused to branchiae but distally free, slightly folded; from middle body region lower portion becoming detached from branchiae and tapered; in far posterior chaetigers lamella somewhat triangular, fused to branchiae over a narrow portion. Prechaetal notopodial lamellae triangular, indistinct, present until about chaetiger 40. Neuropodial postchaetal lamellae rounded from chaetiger 2, from chaetiger 38 slightly notched and becoming divided into large rounded neuropodial lamellae and small conical ventral (or subpodial) lobe from about chaetiger 48; neuropodial lamellae foliate and in approximate interramal position from chaetiger 50.

Anterior chaetae all capillaries with narrow sheaths; arranged in two rows in both rami, capillaries in anterior row slightly shorter and granulated, capillaries in posterior row smooth or slightly granulated; 2–3 superiormost very long chaetae present in notopodia. Parapodia of the middle body region with capillaries having narrow sheaths arranged in two rows; neurochaetae granulated and about the same length in both rows; notochaetae in anterior row shorter, granulated, in posterior row longer, only slightly granulated; two very long superiormost capillaries present in notopodia. From chaetiger 44 neuropodial hooded hooks present, hooks bidentate with very upright apical tooth surmounting main fang ( Fig. 4 B), hooks numbering up to 14 per fascicle accompanied by 1–2 superior and 1–2 inferior smooth alimbate capillaries; notochaetae smooth capillaries with very narrow sheaths or alimbate, first arranged in irregular rows, more posteriorly arranged in a bundle; notopodial hooks from chaetiger 98, same appearance as in notopodia, maximally three per fascicle, together with several capillaries. Inferior capillaries or sabre chaetae not observed.

Nature of the pygidium unknown based on examination of the incomplete holotype. Imajima (1992) identified specimens from Japan as S. kudenovi (see remarks below) and observed an entire ventral cushion as well as a dorsal anus.

Notes on the single specimen examined in the course of the present study: Specimen in poor condition, broken just behind the caruncle and distorted so that prostomial and peristomial features difficult to observe, observation of anteriormost chaetigers also unreliable. Anterior fragment with about 51 chaetigers, total length 9.8 mm, width ~ 1 mm (measured at chaetiger 10, chaetae and postchaetal lobes omitted). Prostomium anteriorly trifid with long pointed median lobe, posteriorly less tapered, separated from anterior part of the prostomium by shallow transverse furrow, caruncle slightly inflated, attached to dorsum. Palps lost. Low but distinct tcb´s present throughout the fragment present. Chaetiger 1 with postchaetal lamellae and capillary chaetae in both rami. Branchiae from chaetiger 2, separated from notopodial lamellae at tip, in further posterior chaetigers branchiae and notopodial lamellae basally fused; neuropodial postchaetal lamellae rounded, from chaetiger 33 neuropodial postchaetal lamellae slightly notched, becoming divided into foliate subulate neuropodial lamellae and small conical ventral (or subpodial) lobe by chaetiger 37. Neuropodial hooded hooks present from about chaetiger 38, numbering 1–5 per fascicle; notopodial hooks absent in examined anterior fragment.

A middle fragment of the specimen from the Lizard Island area was used for molecular studies and is no longer extant (sequences are uploaded to GenBank, Acc. No. KP636516 , Table 1 ).

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

Methyl green staining pattern. Inconspicuous. Prostomium, peristomium, branchiae and postchaetal lamellae most intensely stained.

Remarks. Though our specimen from Lizard Island is in poor condition it could be identified as S. kudenovi Hartmann-Schröder, 1981 . The most striking features of this species are the prostomial shape (anteriorly trifid with slightly inflated caruncle attached to the dorsum and separated from the anterior part of the prostomium by a shallow transverse furrow) and the bidentate hooks with a strikingly upright apical tooth. There is also good agreement in details concerning parapodial postchaetal lamellae, chaetae, branchiae, the development of the first chaetigers and the presence of transversal ciliated bands throughout the body. Slight differences concerning the presence of hooks in neuropodia might be attributed to different growth stages of examined specimens: In the Lizard Island specimen neuropodial hooded hooks start from about chaetiger 38, numbering 1–5 per fascicle, whereas Hartmann-Schröder (1981) states the neuropodial hooks to start on chaetiger 44 in the holotype, numbering up to 14 per fascicle. Imajima (1992) found Scolelepis specimens in Japan which he identified as S. kudenovi . Based on his description and illustrations, differences to the Australian specimens concern the prostomial shape in that the prostomium is anteriorly long and pointed in the Japanese specimens instead of being anteriorly trifid as in the Australian specimens. Also, Imajima (1992) describes up to 17 hooks per fascicle being first present in neuropodia of chaetigers 26–33 and in notopodia from about chaetigers 55–62. In Australian specimens neuropodial hooks start later and are fewer in numbers (see above); notopodial hooks in contrast start much later than in the Japanese specimens and were first observed by Hartmann-Schröder (1981) from chaetiger 98. At all localities specimens had 2–3 notopodial hooks per fascicle in respective chaetigers. Both authors reported hooks to be of the same shape in both rami and described them as bidentate and hooded. However, Hartmann-Schröder (1981) provides an illustration of hooks which clearly shows a large upright apical tooth surmounting the main fang whereas in Imajima’s (1992) illustrations the apical tooth is less distinct, smaller in comparison and not strictly upright. Re-examination of the holotype of S. kudenovi reveals that Hartmann- Schröder’s illustrations are correct and very well reflect the nature of the hooks in this species. The specimen from Lizard Island has the same type of hooks and thus agrees well with the original species description ( Fig. 4 B). Unfortunately taxonomic information on S. kudenovi is restricted to the above mentioned publications and intraspecific variability is largely unknown. In any case, records of S. kudenovi from Japan should be critically reviewed, including the information on the pygidium added to the description of S. kudenovi based on examination of complete specimens from Japan.

A species very close to S. kudenovi specimens from Japan is Scolelepis (Scolelepis) sagittaria Imajima, 1992 , so far only known from Japan. The species has an anteriorly trifid prostomium. Parapodial postchaetal lamellae, chaetae, branchiae, and the development of the first chaetigers is very similar to S. kudenovi . In contrast to S. kudenovi , a species only bearing bidentate hooks, a single superior tridentate hooded hook occurs next to bidentate hooded hooks in the neuropodia and all notopodial hooks are tridentate.

Habitat / Ecology. In Australia the species was found intertidally in fine sand with detritus and Posidonia seedlings (Western Australia), around Lizard Island in sand. The record from Japan is from 45 m water depth ( Imajima 1992).

Distribution. Japan: off Shimoda, Australia: WA, QLD.

Figures

FIGURE 4. Scolelepis (Scolelepis) kudenovi Hartmann-Schröder, 1981, holotype, ZMH P 16497. A. Anterior end, dorsal view, first left parapodium removed, palps lost; B. Neuropodial bidentate hooded hooks from posterior chaetiger, note upright large apical tooth. Scale bars: A = 0.5 mm, B = 10 µm.