Cyerce basi, 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 basi sp.nov.

( Figs 15C, 17B, 18)

LSID: zoobank.org:act: 7633C78B-DFA6-49BC-80A8- 2A8262D8E6D6.

Type material

Holotype: Koumac , New Caledonia, 11 Sep 2018, leg. Koumac 2.1 Expedition (stn. KM202 ), 14 mm preserved length (isolate AV251, MNHN IM-2013-86242 ).

Other material examined

Wongat Island , Madang Province, Papua New Guinea, 29 Nov 2012, leg. J. Goodheart, 1 specimen 3 mm preserved length, dissected (isolate MM87 , CASIZ 191437 ). Koumac, New Caledonia, 29 Sep 2018, leg. Koumac 2.1 Expedition (stn. KR644), 1 specimen 10 mm preserved length, dissected (isolate AV684, MNHN IM-2013-86241 ) . Segond Channel , near Maritime College, Espiritu Santo Isl., Vanuatu, 4 Oct 2006, 8 m depth, leg. Y. Camacho and M. Pola, 1 specimen (isolate 06 Van 01, CASIZ 177095 ) . Near Madang Lighthouse, Madang, Papua New Guinea, 30 m depth, 15 Jan 1988, leg. R.C. Willan, 1 specimen ( CASIZ 065775 ) . Cement Mixer Reef , Madang Papua New Guinea, 23 m depth, 24 Nov 1990, leg. T.M Gosliner and G. Williams, 1 specimen ( CASIZ 075849 ) . ‘ Lago de Oro House Reef ’, south side of reef/lagoon channel, Verde Island Passage coast, Philippines, 13 May 2014, leg. T.M Gosliner, 1 specimen (isolate 14 Cal 04, CASIZ 199270 ) .

Range

Vanuatu, Papua New Guinea, New Caledonia, Philippines (present study).

Description

External morphology: Body translucent, nearly transparent ( Fig. 15C). Rhinophores translucent white with white speckling at tips. Cerata leaf-like, inflated, obovate, translucent, with red hue in some specimens, with white vein-like striations throughout; fluorescent green spot at base of each ceras. Several brown structures inside cerata, not part of digestive gland. White vein-like striations connect to infra-marginal white clusters along ceratal margin, white clusters with brown speckles. Cerata margin outlined with minute white specks.

Internal morphology: Pharynx about 3.5mm in length; pharyngeal pouch larger than buccal bulb. Radula with 10 teeth in a 10 mm preserved length specimen (MNHN IM-2013-86241); 5 teeth on descending limb (leading tooth tip broken off), 5 teeth on ascending limb ( Fig. 18A). Teeth narrow, elongate, slightly bent, about 600 µm in length, with pointed tips ( Fig. 18B). Two rows of ~15 denticles along either side of active tooth. Denticles short, blunt, triangular. Denticle size varies along tooth, smaller at the base, larger distally. Ascus containing about 5 used teeth ( Fig. 18C). Penial stylet embedded in penis, curved inward, extended tip pointed downward, about 100 µm in length ( Fig. 17B).

Ecology

Diet unknown.

Etymology

This species is named in honour of Johan Bas, underwater photographer and naturalist from Nouméa, New Caledonia, in appreciation for the numerous specimens he collected for this and other studies.

Remarks

Species delimitation and phylogenetic analyses all supported Cyerce basi sp. nov. as a candidate species distinct from other members of the C. elegans species complex ( Fig. 1B; Table 3). Cyerce basi sp. nov. was recovered as sister to the clade of C. whaapi sp. nov. and C. elegans ( Fig. 1B). Both C. basi sp. nov. and C. whaapi sp. nov. have white vein-like striations throughout the cerata, but C. elegans does not. The white clusters along the cerata margin are also very similar in C. basi sp. nov. and C. whaapi sp. nov., being larger and deeper than in C. elegans . In radular morphology, the teeth of C. basi sp. nov. have a distinct pointed tip that clearly protrudes beyond the most distal pair of denticles, whereas in C. whaapi sp. nov., the tip of the teeth is very inconspicuous, and the distal pair of denticles are located near the end of the teeth.

Bergh’s (1871) original description of C. elegans did not mention vein-like structures throughout the cerata as observed in our specimens of C. basi sp. nov. However, the specimen of C. elegans described by Bergh (1888) from the Indian Ocean as C. elegans var. did exhibit the white vein-like striations as observed in our specimens. Bergh (1888) also described the penial stylet as being a sharp-angled, tapered hook and refers to the illustration of the penial stylet from his original description of Cyerce elegans , suggesting these two specimens potentially had similar penial stylets. The penial stylet of our specimens of C. basi sp. nov. closely resembles the stylet described by Bergh (1871), as being short, recurved, with an oval opening and pointed tip. Bergh (1888) also described the radular morphology of the specimen from the Indian Ocean as similar to the radula of C. elegans from Palau. The radula of our specimens of C. basi sp. nov. also closely resembles the radula described by Bergh (1871, 1888).

32 • Moreno et al.