Phanerophthalmus lentigines Austin, Gosliner & Malaquias, 2018

Description

Maximum TL = 9 mm (in fixed spc.). Body cylindrical, elongated; white, covered with golden-brown speckles. Ventral side white. Cephalic shield triangular, elongate and notched. Parapodial lobes apparently not overlapping. Shell visible. Eyes visible; periocular area unpigmented. Conspicuous rounded cluster of white pigmentation concentrated between the eyes and along the margin of the parapodial lobes. Red-orange dots present on the mantle. Maximum shell H = 1.5 mm (fixed spc. TL = 9 mm); shell external, plate-like, thin, fragile, white to translucent; oval; left side straight, right side slightly convex; anterior end rounded; posterior end angled, oblique, lacking a pointed shoulder. Jaws semi-circular, elongate; rods ending in 3-5 finger-like denticles. Radula formula 33×10.1.10 (fixed spc. TL = 7 mm) and 35×7.1.7 (fixed spc. TL = 9 mm); lateral teeth hook-shaped with cusp elongated, pointed and thinner margins, broad base; rachidian with central cusp triangular, pointed, with thinner margins, and one small triangular cusp on either side. Gizzard plates with one row of rods on top of ridges. Penial sheath wider than seminal duct; seminal duct twice the length of penial sheath; prostate oval, bulbous, compact, ca. 1/3 length of seminal duct.

Distribution

Western Indian Ocean from Mozambique to the West Pacific off the east coast of Papua New Guinea and north to the Ryukyu Islands, Japan (Fig. 25). Type locality: Zavora Rock Pool, Mozambique. Intertidal and shallow subtidal down to 6 m on sandy and rocky boulders covered with green algae.

Etymology

Verbatim from the original description (Austin et al. 2018, Invertebrate Systematics 32: 1374):

After its freckled appearance (L. lentigines = freckles).

Remarks

Described as a new species in a 2018 systematic revision of Phanerophthalmus. The authors noted:

This species resembles P. perpallidus both in external morphology and internal anatomy, which makes them difficult to separate based on morphology alone. Nevertheless, they proved to be genetically distinct (COI uncorrected p-distance = 10.0%; Table 2; PP = 1, BS = 100; Fig. 1) and we could recognise 65 different mutations between the species ... Moreover, P. lentigines is distinguished from all other species in the genus by the presence of five synapomorphies in the region of the COI gene here studied

(p.1374). The two species have partially overlapping distributions in the West Pacific between New Guinea and southern Japan and have often been misidentified in the literature as P. cylindricus (Gosliner et al. 2008, 2015; Malaquias and Tibiriçá 2017).

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References

• チョウチョウミドリガイ属の1種, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
• Phanerophthalmus sp. 4, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• Austin J., Gosliner T. & Malaquias M.A.E. (2018). Systematic revision, diversity patterns and trophic ecology of the tropical Indo-West Pacific sea slug genus Phanerophthalmus A. Adams, 1850 (Cephalaspidea, Haminoeidae). Invertebrate Systematics. 32(6): 1336-1387. https://doi.org/10.1071/is17086
• Phanerophthalmus sp. 7, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.
• Oskars T.R., Too C.C., Rees D., Mikkelsen P.M., Willassen E. & Malaquias M.A.E. (2019). A molecular phylogeny of the gastropod family Haminoeidae sensu lato (Heterobranchia: Cephalaspidea): a generic revision. Invertebrate Systematics 33(3): 426-472.