Coryphellina pannae Ekimova, Deart, Antokhina, Mikhlina & Schepetov, 2022

Location: Iwahone, Jogashima, Kanagawa, Japan
Date: 2018/10/19
Length: 3mm
Depth: 15.0m
Water temperature: 22.5℃

Description

The smallest member of the species complex, reaching only about 6 mm in length (preserved). Background color ranges from translucent white to pale lilac. Foot slender with long anterior corners. Rhinophores densely papillated, 1.5-2 times shorter than the oral tentacles, light pink with purple subapical rings and white tips. Oral tentacles translucent violet, more intensive toward the tip, with a white tip. Cerata finger-shaped, pointed distally, with digestive gland diverticula filling about half of the ceratal volume; arranged in up to five rather sparse groups per side, with only 8-9 cerata in the first group and about 3 in the second — the lowest counts in the species complex. Each ceras is milky white, with a white to pale-yellow cnidosac area beneath a red subapical ring. Three continuous pink longitudinal lines (one dorsal, two dorsolateral) run from head to tail and merge on the dorsal surface of the tail.

Distribution

The type locality is Dambay, Hon Tre Island, Nha Trang Bay, Central Vietnam, at 5 m depth on artificial substrate (an old net) over a sandy bottom. At present, the species is recorded only from this type locality.

Etymology

The specific epithet pannae honours Panna I. Ekimova, mother of the first author.

Remarks

The combination of small body size, low number of ceratal groups, translucent white-to-lilac background, and three continuous pink longitudinal lines distinguishes this species from the other members of the C. rubrolineata species complex. In line pattern it most resembles C. rubrolineata, but is readily separated by the absence of the dense white opalescent powder that C. rubrolineata carries on the distal parts of the rhinophores and oral tentacles.