Philine orientalis A. Adams 1854

Philine orientalis A. Adams, 1854

Figure 5

Philine orientalis A. Adams 1854: 94–95.

Philine argentata Gould 1859: 139.

Philine japonica Lischke 1872: 105 –106.

Philine striatella Tapparone-Canefri 1874: 109 –110, pl. 2, fig. 9.

Type material. Syntypes of Philine orientalis (NHMUK 20080105): 3 specimens, Eastern Seas.

Holotype of Philine argentata (USNM 1680): “ Hakodadi Bay [= Hakodate, Japan], not examined.

Type material of Philine japonica and Philine striatella unknown.

Other material examined. Bodega Bay, California, 31 Jul 1996, 2 specimens, 26–32 mm preserved length (CPIC 00781); 2 specimens 26–27 mm preserved length (CPIC 00782). Foster City, California (37º34.5’N, 122º15.5’W), 0 m depth, 12 Jul 1996, 7 shells, 15–25 mm long, leg. E.V. Coan, (LACM 96-11.2).

Description. Live animal to 40 mm, uniformly white. Cephalic shield shorter than posterior shield (Fig. 5 A). Posterior shield with a round notch. Parapodial lobes thick and muscular, nearly as wide as the cephalic shield, even in preserved specimens (Fig. 5 B). Shell to 20 mm, internal, large, oval, nearly as broad posteriorly (at apex) as anteriorly (Figs. 5 C–D). Lip rising roundly above apex. Sculpture composed of growth lines, sometimes fine punctate striae.

Radular formula 18 x 1.0.1. Radular teeth broad with 35–42 small denticles. Gizzard plates (3) spindle-shaped with small to medium, round to oval, shallow pores (Fig. 5 H). Paired plates (2) broad (Figs. 5 F–G) filling entire anterior portion of body, unpaired plate (1) much smaller and narrower (Fig. 5 E).

Range. Native to Japan, Taiwan and Malaysia, introduced in the San Francisco Bay Area, from Bodega Bay to San Mateo County, California.

Remarks. Confusion around the identity of this invasive species was conclusively resolved by Krug et al. (2012) using molecular data. For anatomical descriptions see Price et al. (2011). For population genetics see Krug et al. (2012). It can be easily distinguished from P. auriformis in the areas where both species coexist by the wider body of P. orientalis, with broad parapodial lobes. Philine paucipapillata Price, Gosliner & Valdés, 2011 is another similar species originally described from Cambodia. Differences between P. paucipapillata and P. orientalis include the penial morphology and the denticulate edge of the radular teeth, which is undulated in P. paucipapillata (see Price et al. 2011). The specimens here examined from Bodega Bay (CPIC 00782) have a variable denticulate edge of the teeth, undulated in some teeth and straight in others, which appears to be intermediate between P. paucipapillata and P. orientalis. However, unpublished molecular data from those specimens confirm they are P. orientalis; also the morphology of the penial papillae (not illustrated) is consistent with this hypothesis. Anatomical and molecular studies have confirmed the presence of P. orientalis in the Pacific coast of North America (Price et al. 2011, Krug et al. 2012) but failed to reveal the presence of P. paucipapillata in this region. The variable denticulate edge of the teeth in the species here examined puts into question to validity of P. paucipapillata.