Siphopteron nakakatuwa Ong & Gosliner, 2017

Location: Pulau Flores, Indonesia
Date: 2011/09/28
Length: 10mm
Depth: 12.0m
Water temperature: 27.0℃

Description

A small siphopteran 4–7 mm in length. Parapodia and foot ground colour translucent white to orange. White spots covering parapodia; each spot lined by bright orange. Parapodia lined with accents converging on foot. White spots with opaque white punctations inside larger spot. These large spots dotting head shield, parapodia and visceral hump.
Visceral hump rounded with long flagellum near midline of body. Elongate flagellum opaque vermillion with white spots ending with black tip. Foot translucent white, lined with orange edges and central white triangular stripe down middle. Stripe merging into yellow tip. Head shield roughly triangular, broadest anteriorly, and narrowing posteriorly into siphon. Siphon with central white stripe on anterior face, bisecting vertically. Posterior side of siphon with prominent ridge extending above lateral margins. Siphon with vermillion ground colour and yellow tip with vermillion edges and white spots. Gill with four simple folds.
Shell: No trace of a shell found in specimen dissected. Radular formula 16 × (4·1·0·1·4) in one specimen (NMP 041185). Inner lateral teeth broad with single primary cusp. Masticatory margin of inner laterals broad with two large, well-separated, triangular denticles. The penis is complex with elongate, highly convoluted prostate. Penial sac straight, containing approximately 13 large, posteriorly directed, acutely pointed cuticular spines (ps1). More posteriorly, at base of penial sac, are about 14 slightly canted, bifid, or trifid spines (ps2). Another series of 19 small spines found on the right side of the anterior portion of penial sac (ps3). Secondary papilla found at the anterior end of penial sac appearing to have acutely pointed cuticular spine.

Distribution

Type locality: Cemetery Beach, Tingloy, Batangas, Luzon, Philippines. Thus far, known only from the Philippines and Indonesia.

Etymology

Verbatim from the original description (Ong et al., 2017, p.775):

The species epithet, nakakatuwa, is a Tagalog word meaning

amusing or cute"."

Remarks

Originally described as Siphopteron nakakatuwa Ong & Gosliner, 2017. This species corresponds to specimens previously figured as Siphopteron sp. 7 (Gosliner, Valdés & Behrens, 2015).
The colour pattern of S. nakakatuwa, with an orange body colour with prominent white spots, is unique to this species. Morphologically, this species is similar to S. flavolineatum and Siphopteron quadrispinosum Gosliner, 1989, both of which have an inner radular tooth with two large quadrangular cusps. S. quadrispinosum differs in its colour pattern with a yellow body with red pigment on the apex of the siphon and on the flagellum. This species also has a white margin along the edge of the parapodia. S. flavolineatum differs from S. nakakatuwa in having an ochre rather than orange pigment on the body, dark pigment only on the tip of the siphon and flagellum, and in having a narrow yellow medial line on the foot as compared to a triangular white one in S. nakakatuwa.
Internally, the radula of all three species is very similar. The penial morphology of S. nakakatuwa is very similar to that of S. flavolineatum, with the exception that the largest spines of S. nakakatuwa are much larger than those of S. flavolineatum. The penis of S. quadrispinosum has four large basal cuticular spines with no smaller spines. In S. nakakatuwa, there are also small spines on the penial papilla, with four distinct areas of spines, each with numerous spines. Phylogenetically, S. nakakatuwa and S. flavolineatum are sister species and are found sympatrically in the Philippines. The two differ in their COI gene sequences by 8.8 %.