Monday, June 3, 2019

[Gastropoda • 2019] Laocaia simovi • A New Semislug of the Genus Laocaia (Pulmonata, Helicarionidae) from Vietnam


 Laocaia simovi Dedov & Schneppat

in Dedov, Schneppat, Vu & Huy, 2019. 

Abstract
A new species of the genus Laocaia Kuzminykh, 1999, Laocaia simovi Dedov & Schneppat, sp. nov., is described, which was collected from a single locality in northern Vietnam. Color pictures of living specimens are provided. For the first time, information on the ecology and biology of a representative of the genus Laocaia is presented.

Keywords: Helicarionidae, Laocaia, new species, Vietnam


Family Helicarionidae Bourguignat, 1877
Subfamily Helicarioninae Bourguignat, 1877
Genus Laocaia Kuzminykh, 1999

Type species: Laocaia attenuata Kuzminykh, 1999.

Diagnosis: small slugs with non-coiled visceral hump, rounded posteriorly, lying in V- shaped body groove; body cavity not extending into tail; shell very thin, non-spiral, internal, hemispheric, completely covering visceral hump, with small calcified part; penis short, bulbous, with large stimulator inside; epiphallus and flagellum absent; spermatheca entering atrium between vagina and penis (amended after Kuzminykh 1999).

Remarks: for the systematic position of the genus Laocaia, we here follow MolluscaBase (2018). The genus was originally placed in the family Ariophantidae by Kuzminykh (1999), which was followed by Bouchet et al. (2017). However, Schileyko (2002, 2011) transferred it to the family Helicarionidae.

Figure 3. Laocaia simovi Dedov & Schneppat, sp. nov. coloration of the body with the visceral hump and U-shaped dorsal groove.

Laocaia simovi Dedov & Schneppat, sp. nov.

Differential diagnosis
Externally, L. simovi Dedov & Schneppat, sp. nov. differs from L. attenuata and L. obesa by its coloration. The anterior body of L. attenuata is yellow, and its head and neck show three indistinct stripes, while the mantle is marbled with irregularly arranged black spots. The posterior part of the foot is uniformly grayish. In contrast, the body of L. obesa is whitish-grayish colored and covered with numerous white spots. On the visceral hump, the mantle of this species displays a pattern of irregularly arranged black spots (Kuzminykh 1999).

Anatomically, L. simovi sp. nov. differs from L. attenuata by the narrower base of the penis, as well as by its much more globular sarcobelum with a pointed, cone-shaped apical tip. The sarcobelum is not covered with numerous distinct papillae, but it shows very fine longitudinal striae. The striation is not well visible even under high magnification.

Laocaia simovi sp. nov. differs from L. obesa by its less voluminous penis and the narrower base of the penis. The inner wall of the penis is not covered with papillae, but with almost invisible, very fine granules. The bursa copulatrix of L. simovi sp. nov. is of almost globular shape, the pedunculus is long, slender and of the same diameter all along its length; its bursa copulatrix is more voluminous than the penis.

Figure 6. Laocaia simovi Dedov & Schneppat, sp. nov. pointed posterior end of the dorsum with the horn-like structure (A) and the coloration of the slime (B).

Derivatio nominis: 
This new species is named after our friend and biologist Dr. Nikolay Simov, NMNHS, Sofia, Bulgaria, who found the first specimen of the species.

Figure 1. Laocaia simovi Dedov & Schneppat, sp. nov. habitat picture, from the type locality near the peak of Fansipan. The black arrow points towards the epiphytic plants, in which the new species was found.


 Ivaylo Dedov, Ulrich Schneppat, Manh Quang Vu and Nguyen Quoc Huy. 2019. A New Semislug of the Genus Laocaia (Gastropoda, Pulmonata, Helicarionidae) from Vietnam. ZooKeys. 846: 19-30.  DOI: 10.3897/zookeys.846.34372

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