Cyerce trowbridgeae, Moreno & Medrano & Gosliner & Wilson & Krug & Valdés, 2025

Moreno, Karina, Medrano, Sabrina, Gosliner, Terrence M., Wilson, Nerida G., Krug, Patrick J. & Valdés, Ángel, 2025, Phylogenetic systematics of the genus Cyerce Bergh, 1870 (Mollusca: Heterobranchia: Sacoglossa: Caliphyllidae) from the Pacific and Indian oceans with descriptions of nine new species, Zoological Journal of the Linnean Society 204 (1) : -

Cyerce trowbridgeae sp.nov.

( Figs 9A, 11B, 12)

LSID: zoobank.org:act: 06B7161E-69C2-46F7-B955-0632D 533657F.

Cyerce sp. 2 Gosliner et al. 2018: 402 upper right photo.

Cyerce sp. 6 Nakano 2018: 119.

Type material

Holotype: Bigej-Meck Reef , Kwajalein Atoll, Marshall Islands, 6 Aug 2007, leg. S. Johnson, 7 mm preserved length, dissected (isolate MM76 , CASIZ 181975 ).

Range

Marshall Islands (present study) and Japan ( Nakano 2018).

Description

External morphology: Body colour greyish-brown ( Fig. 9A). Head beige with light brown striations; light grey banding outlining eyes, extending to rhinophores. Rhinophores beige with light brown to burgundy reticulated striations throughout; scattered yellow spots at tips. Cerata flat, slightly inflated, obovate; colour greyish-brown with vein-like light brown striations throughout; outer side of cerata scattered with small elevated white minute specks; inner side of cerata scattered with black to dark brown elevated spots. Ceratal margin outlined with several elevated bright yellow spots creating dentate-like structure; two dark grey bands along either side. Foot beige dorsally with light brown vein-like striations; foot margin with light grey and scattered bright yellow spots.

Internal morphology: Pharynx about 1 mm in length; buccal bulb similar in size as pharyngeal pouch. Radula with more than 11 teeth in a 7-mm preserved length specimen ( CASIZ 222039) ( Fig. 12A). Teeth very elongated, about 600 µm long, with small triangular tips. Two rows of ~26 short triangular denticles ( Fig. 12B). Penial stylet elongate, curved, about 200 µm in length, cylindrically shaped, hollow with oval opening ( Fig. 11B).

Ecology

Found on the green algae Halimeda spp.

Etymology

This species is named in honour of Cynthia Trowbridge in recognition of her long career and outstanding contributions to the biology and ecology of sacoglossans.

Remarks

All species delimitation analyses supported Cyerce trowbridgeae sp. nov. as distinct from C. bourbonica , which was its sister taxon in phylogenetic analyses ( Fig. 1A). External characteristics shared between Cyerce trowbridgeae sp. nov. and C. bourbonica include yellow spots outlining the margin of the cerata and small white pustules throughout the cerata observed in both species. However, Cyerce trowbridgeae sp. nov. was morphologically distinct from all other Cyerce spp. examined, possessing greyish cerata with light-brown reticulated striations, white elevated specks on the outer ceratal surface, and black to dark brown elevated spots on the inner ceratal surface. The cerata of C. bourbonica are lobate and light cream to greyish (depending on locality), whereas cerata of C. trowbridgeae sp. nov. are fan-shaped and a much darker shade of brown. Moreover, C. trowbridgeae sp. nov. has dark brown reticulated striations across the cerata, head, and rhinophores that are not present in C. bourbonica . A dark grey band outlines the margin of the cerata, foot, and head in C. trowbridgeae sp. nov. that is only faintly observed along the ceratal margin of C. bourbonica . The radular teeth of C. bourbonica are much shorter and wider than those of C. trowbridgeae sp. nov. The denticles along the radular teeth of C. trowbridgeae sp. nov. are also more numerous and more triangular in shape than of the denticles in C. bourbonica . Also, C. bourbonica appears to have a short straight penial spine whereas that of C. trowbridgeae sp. nov. is elongate and curved.