Phyllidia polkadotsa Brunckhorst, 1993

Description

A phyllidiid 15–25 mm long. The dorsum is golden yellow with numerous (more than 10) large, round black spots. Both dorsally and ventrally the background is gold (whitish in the preserved state). The notal tubercles are small, simple and rounded, evenly distributed over the dorsum, and three low median longitudinal ridges are present. Tubercles and ridges adopt the colour of their immediate background. The rhinophores are gold with 11–13 lamellae. The hyponotum is golden with black spots showing through where they occur. Gills, foot and the triangular oral tentacles are also gold.

Distribution

Known only from the Hawaiian Islands (Oahu: Makua, Pupukea; Haleiwa; Hawaii Island). Type locality: Makua, Oahu (6–10 m).

Etymology

Verbatim from the original description (Brunckhorst, 1993, p.43):

The name refers to the flamboyant, dorsal pattern of black polka dots on a golden yellow background.

Remarks

Described as a new species in Brunckhorst, D.J. 1993 Records of the Australian Museum, Supplement 16: 1-107. The author noted:

Phyllidia polkadotsa is distinctively patterned. The dorsum is gold with black spots. Ventrally, it is coloured gold. The notal tubercles are low and rounded and there are three low, median longitudinal ridges. The male reproductive organs are elongate compared to other Phyllidia species

(p.43). The Mediterranean Phyllidia flava is also gold but has relatively larger tubercles capped in white and lacks black pigmentation. Phyllidiopsis loricata bears black spots but has a pale cream to white background. P. ocellata differs in having grey ventral colouration, more rhinophoral lamellae (27-30) and the absence of three low dorsal longitudinal ridges.

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References

• Phyllidia polkadotsa n.sp., Brunckhorst D.J. (1993). The systematics and phylogeny of phyllidiid nudibranchs (Doridoidea). Records of the Australian Museum, Supplement 16: 1-107.
• ポルカドットイボウミウシ（新称）, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
• Phyllidia polkadotsa, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.