Melanochlamys fukudai S. Cooke, Hanson, Y. Hirano, Ornelas-Gatdula, Gosliner, Chernyshev & Á. Valdés, 2014

Description

A small headshield slug 3-11 mm in preserved length, with an elongate, relatively wide and short body. The cephalic shield occupies about half the body length and is roughly rectangular, slightly wider anteriorly. Parapodia are well developed and run almost the entire length of the body. Body colour ranges from brownish to purple-black and is uniform across the body except for the cephalic shield, which is paler and bears a central longitudinal line of darker pigment — a diagnostic feature of this species. Male reproductive system (Form I.b): prostate elongate, simple, curved, with no folds and a wider distal end. Penis elongate with a cuticularised penial spine on the tip; spine slightly curved with a broad proximal base narrowing gradually to a sharp distal tip. Spermatic bulb consists of a folded tube ending in a wider vesicle distally and bearing a retractor muscle. Shell broad and relatively deep, with a small spire and a shallow indentation on the posterior left side of the body whorl.

Distribution

Temperate and cold waters of Japan (Hokkaido to Sagami Bay). Type locality: Banzu, Kisarazu, Boso Peninsula, Chiba Prefecture. Also recorded from Onnetto (Hokkaido), Matsukawa-ura, Souma (Fukushima), Ena Bay, Miura (Kanagawa), Mikawa Bay (Aichi), Ise Bay (Mie), Aio Bay (Yamaguchi), and Sagami Bay. Found on intertidal mudflats during low tide.

Etymology

Verbatim from the original description (Cooke et al. 2014, Zoologica Scripta, p.13):

Dedicated to Dr. Hiroshi Fukuda, who was the first person to recognize this species as undescribed, for his valuable contributions to malacology in Japan.

Remarks

Described as a new species in Cooke, Hanson, Hirano, Ornelas-Gatdula, Gosliner, Chernyshev & Valdés 2014 Zoologica Scripta. The author noted:

Melanochlamys fukudai is characterized by having a uniform, dark external coloration with a dark longitudinal line on the cephalic shield. Anatomically, M. fukudai is most similar to M. diomedea but the spermatic bulb is shorter ending distally in a distinctive vesicle in the M. fukudai, whereas in the M. diomedea is a longer, tightly packed duct

(p.13). The species displays poecilogony: Fukushima specimens produce large eggs (ca. 160 µm) that hatch into large, short-pelagic veligers (ca. 231 µm shell length), whereas Chiba and Kanagawa specimens produce small eggs (ca. 100 µm) that hatch into smaller (ca. 159 µm) longer-swimming veligers.

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References

• Melanochlamys fukudai sp. n., Cooke S., Hanson D., Hirano Y., Ornelas-Gatdula E., Gosliner T.M., Chernyshev A.Y. & Valdés A. (2014) Cryptic diversity of Melanochlamys sea slugs (Gastropoda, Aglajidae) in the North Pacific. Zoologica Scripta 43: 351-369.