Spiophanes pisinnus, MEISSNER & Hutchings, 2003

MEISSNER, Karin & Hutchings, Pat A., 2003, Spiophanes Species (Polychaeta: Spionidae) From Eastern Australia-With Descriptions of New Species, New Records and an Emended Generic Diagnosis, Records of the Australian Museum 55, pp. 117-140 : 133

Spiophanes pisinnus n.sp.

Fig. 12

Spiophanes sp. 4.–Wilson & McDiarmid, 2003.

Type material. HOLOTYPE: Australia, New South Wales , Pittwater , Longnose Point , 33°37.3'S 151°18.2'E, in 15 m,Apr 1992, ( AM W24085 ). PARATYPE: Australia, New South Wales , Pittwater , 33°35.77'S 151°18.29'E, in 15.9 m, Jun 1995, 1 specimen ( AM W23683 ) .

Description. Holotype complete, with 31 chaetigers; total length about 4 mm, 0.3 mm wide. Incomplete paratype with 25 chaetigers, about 0.4 mm wide. Body slender, subcylindrical. Prostomium broad anteriorly, bell-shaped; anterior margin convex, with rounded, short anterolateral projections (Fig. 12A). Occipital antenna absent. Up to three single small eye spots forming 2 larger pigmented spots on the posterior part of the prostomium (Fig. 12A). Nuchal organs as pair of dorsal loops, extending from posterior prostomium margin to beginning of chaetiger 4 (Fig. 12A). Peristomium poorly developed. Parapodia of chaetiger 1 in dorsolateral position; postchaetal lamellae cirriform, about equal in length in both rami. Parapodia of chaetiger 2 also dorsolateral, parapodia 3–4 situated laterally (Fig. 12A). Notopodial postchaetal lamellae of parapodia of chaetigers 2–4 cirriform to subulate; neuropodial postchaetal lamella of chaetigers 2–3 subulate, in chaetiger 3 with rounded tip, postchaetal neuropodial lamellae of chaetiger 4 rounded (Fig. 12B). Chaetigers 5–8 with subtriangular, distally rounded notopodial lamellae; neuropodial postchaetal lamellae reduced (Fig. 12C). From chaetiger 9, notopodial lamellae subulate to subtriangular, with elongate tips; neuropodial lamellae reduced (Fig. 12D,E). Chaetal spreader of “0+1 type” with semicircular glandular opening well developed on chaetigers 5–7 (Fig. 12C); opening of glandular organs of chaetigers 9–14 present as lateral vertical slits. Ventrolateral intersegmental genital pouches absent. Dorsal ciliated crests indistinct. Chaetiger 1 with 1–2 stout, crook-like chaetae in the neuropodium; remainder of chaetae capillaries. Notopodia of chaetigers 2–4 with capillaries, most with long, fine tips and narrow sheaths; neurochaetae stouter, bilimbate capillaries with narrow sheaths (Fig. 12M). Notopodial capillaries of chaetigers 1– 4 longer than those in subsequent chaetigers. Arrangement of chaetae not determined. Chaetigers 5–14 with very stout bilimbate neurochaetae, distally pointed (Fig. 12J,O), arranged in 1 irregular row; notochaetae bilimbate capillaries of different lengths, with distinct sheaths, tips pointed and elongate to a varying degree (Fig. 12H,I,K,N), arranged in 3 indistinct rows. From chaetiger 15, notopodia with bilimbate capillaries with narrow sheaths (Fig. 12G,P), arranged in tuft; neuropodia with quadridentate hooks without hoods (Fig. 12F), initially with 3–4 hooks in single row. Bacillary chaetae not emergent in specimens examined. Sabre chaetae begin on chaetiger 4, very long in first parapodia compared to most other species of the genus (Fig. 12L). Single stout, bent capillary chaetae without sheath in posterior notopodia. Pygidium with two robust anal cirri, attached terminally in a ventrolateral position.

Pigmentation. Patch with reddish-brown pigment on prostomium, anteriorly to eyes (Fig. 12A).

Methyl green staining pattern. No discernible staining pattern.

Biology. Species occurs in mud and muddy sand, 15–16 m.

Remarks. This species is most similar to S. wigleyi in having the same type of nuchal organs, a pair of dorsal loops on the first 4 anterior chaetigers. However, S. pisinnus can be clearly distinguished by having non-hooded hooks rather than hooded hooks as well as the chaetal spreader of “0+1 type” with a semicircular glandular opening as opposed to exhibiting a short horizontal glandular opening. The shape of the neuropodial chaetae of chaetigers 5–14 is unique among Spiophanes species.

Etymology. pisinnus —Latin for small, little; referring to the small size of the species.

Geographical distribution. Species known only from the type locality.