Sternaspis spinosa Sluiter, 1882, emended

Sendall, Kelly & Salazar-Vallejo, Sergio I., 2013, Revision of Sternaspis Otto, 1821 (Polychaeta, Sternaspidae), ZooKeys 286, pp. 1-74 : 43-46

Sternaspis spinosa Sluiter, 1882, emended Figure 14

Sternaspis spinosa Sluiter, 1882: 277, Pl. 1, fig. 1.

Sternaspis scutata : Gallardo 1968: 114 (partim).

Type material.

Indonesia. Neotype (NHM 1889.6.15.52-36), Java, Bay of Batavia, "Batavia Roads", outside Jakarta, 30 m, mud, 1889, purchased from Dr. Sluiter.

Additional material.

Indonesia. 1 spec. (ZMA 1491), Irian Jaya, Strait of Galewo, near Seget, 31 m, Stn 163. Thailand. 8 spec. (PMBC C1-0S), west of Takua Pa, 9°00'00"N, 98°02'00"E, 41 m, 17-IV-1998. 1 spec. (PMBC B2-0S), Andaman Sea, NW off Takua Pa, 9°14'00"N, 98°00'00"E, 45 m, 17-II-1998. 1 spec. (PMBC C2-0S), Andaman Sea, W off Takua Pa, 9°00'00"N, 97°56'00"E, 60 m, 17-II-1998. Vietnam. 1 spec. (LACM n 11878), Sta. 126 (no coord.), 17 m, mud, 11-II-1960. 1 spec. (LACM n 11884), Sta. 173 (no coord.), 32 m, sand, 25-II-1960. Australia. 1 spec. (AM W 202648), Queensland, Shoalwater Bay, Triangular Islets. One spec. (AM W 28515), Queensland, Coral Sea, Capricorn Channel, southeast of Swains Reef, 22°31'07"S, 152°42'38"E, 78 m. 2 spec. (AM W 28516), Queensland, Coral Sea, Capricorn Channel, SE off Swains Reef, 22°03'27"S, 152°33'54"E, 100 m. 1 spec. (AM W 28512), Queensland, Coral Sea, Capricorn Channel, 6.8 miles NW off Pine Peak Island, 21°27'30"S, 15°00'48"E, 42 m. 1 spec. (AM W 28517), Queensland, Juno Bay, near Ingham, 18°41'00"S, 146°30'00"E. 1 spec. (AM W 28509), Western Australia, 72 nautical miles NW off Dampier, 19°28'54"S, 116°29'24"E, 110 m.

Description.

Neotype (NHM 1889.6.15.52, No. 36) without adhering sediment and bright white or cream in colour (Fig. 14A), larger specimens sometimes darker. Anterior segments without cuticular papillae, some present on segments 6-8, short, evenly spaced. Following segments with well-defined single rows of clustered, longer filamentous, white papillae; larger specimens with median segments papillae eroded. Neotype 17.5 mm long, 8.7 mm wide; body up to 20 mm long, 8.5 mm wide, about 29 segments.

Prostomium hemispherical, opalescent in larger individuals, translucent in smaller individuals. Peristomium rounded, small. Mouth oval, covered by papillae (bright white in smaller specimens), extends from prostomium to anterior edge of second segment.

First three anterior chaetigers with over 10 bronze, widely separated, falcate hooks (paler in smaller specimens), each with subdistal dark areas (Fig. 14B). Genital papillae protrude ventrally from intersegmental furrow between segments 7 and 8. Pre-shield region with 7 segments, with short delicate fascicles of a few capillary chaetae on some specimens.

Ventro-caudal shield pale brown, usually clean, sometimes with adhered sediment; ribs not well-defined, concentric lines present; suture extended throughout shield, barely visible. Anterior margins angular; anterior depression shallow; anterior keels exposed (Fig. 14C). Lateral margins rounded, expanded posteriorly. Fan truncate, barely projected beyond posterior corners, margin crenulated.

Marginal shield chaetal fascicles include 10 lateral ones, chaetae in a slightly curved arrangement, and five posterior fascicles, chaetae in a narrow oval arrangement. Peg chaetae narrow, sometimes as long as posterior shield chaetae. Additional delicate capillary chaetae between peg chaetae and first posterior fascicle of shield chaetae.

Branchiae tightly coiled, protrude from two very narrow, widely divergent plates on either side of anus. Interbranchial papillae abundant, on either side of anus.

Neotype locality.

Bay of Batavia, Java, Indonesia.

Remarks.

Sternaspis spinosa Sluiter, 1882 has been in doubt ever since the original description because it was described and illustrated with long palp-like appendages; however, this type of appendage has not been reported for any other species, many authors doubt their presence and, by extension, even of the species delineation itself. However, the analysis of the available material has led us conclude that the species is distinct and in order to clarify its taxonomic status ( ICZN 1999, Art. 75.3.1) a neotype has been selected, described and its diagnostic features have been illustrated ( ICZN 1999, Art. 75.3.2-75.3.3). There is no type material available, as indicated by Petersen (2000: 321), but Sluiter identified some other specimens and we have selected one of them as the neotype ( ICZN 1999, Art. 75.3.4). This specimen and all others from the same lot resemble each other and conform to the original materials, at least regarding the shape of the ventro-caudal shield. Further, because Sluiter identified some of them, we are confident they agree with the original (and now lost) materials ( ICZN 1999, Art. 75.3.5). The proposed neotype was collected in the same locality, Bay of Batavia, Java, as the original materials ( ICZN 1999, Art. 75.3.6), and it was deposited in the Natural History Museum, London ( ICZN 1999, Art. 75.3.7).

There are many features separating Sternaspis spinosa from other species, such as the flatter, less ribbed shield, with 10 lateral and five posterior fascicles of shield chaetae, well-defined rows of papillae and longer peg chaetae. The characteristics of Sternaspis spinosa are distinctive compared to Sternaspis costata , and we regard them as separate species. Concerning the presence of palps, Fauvel (1927) did not consider Sternaspis spinosa to be in the family, and Petersen (2000) suggested that Sluiter may have examined a damaged specimen where a portion of the digestive tract had been extruded to the exterior. However, according to Rouse and Pleijel (2001), these appendages may not be part of the gut. There is a thick cuticle, musculature and blood supply to the appendages, which would indicate that they are moveable and have a function in digging or anchoring the body in the sedi ment. There is no groove along the appendages, but the area where they attach near the mouth is heavily ciliated. Sluiter comments that only one of the specimens he collected had these appendages, and that they may have been lost in others due to the method of collection. Petersen (2000) indicated that there are three dried out specimens with Sluiter’s material at the Zoological Museum, University of Amsterdam, but none have the appendages or any trace of them. Sluiter also included two very robust peg chaetae protruding from the underside of the shield near the posterolateral margins. It is unfortunate the types were not located because this species has not been collected or reported since. However, no evidence of the palps, including scars or traces were observed on other specimens (NHM 1889.6.15.52, No. 36)) identified by Sluiter as Sternaspis spinosa .

On the other hand, Sternaspis spinosa resembles Sternaspis africana by having shields with deep anterior depressions and markedly expanded lateral shield margins. However, in Sternaspis spinosa the shield integument is transparent and both ribs and concentric lines are visible, whereas in Sternaspis africana the ribs are barely noticeable. Further, the shield of Sternaspis spinosa has a posterior margin straight, at same level as margin of shield resembling Sternaspis princeps , Sternaspis rietschi , Sternaspis spinosa , Sternaspis thalassemoides and Sternaspis thorsoni sp. n. However, Sternaspis spinosa can be distinguished from them as its shield is much wider than long and by having its anterior keels exposed.

Distribution.

Queensland Australia, Coral Sea, Thailand in the Andaman Sea, Vietnam and Indonesia, 17-110 m depth.