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Pneumodermopsis (Pneumodermopsis) polycotyla (Boas, 1886a)

Overview

This is a small, naked pelagic snail, up to 0.5 cm long, with a mainly transparent body, the visceral mass is seen through the body wall. The skin has brown chromatophores. There is a median sucker arm with 5 suckers of which the anterior two are large oval and pointed. There are two groups, each of 12 suckers on the buccal wall. The posterior gill is absent. The posterior footlobe is long (Pneumodermopsis polycotyla). It is a carnivorous species that lives in the E-Pacific Ocean.

Taxonomic Description

The body shape is typical for this genus, posterior footlobe long, lateral gill long with clear fringes. The body is brownish with chromatophores. The lateral suckers are placed in two rows forming distinct groups each of 10 to 12 suckers. Anterior tentacles large. A well developed median foot tubercle is present. The median arm is well developed, the terminal suckers are larger than the other four suckers, which are subequal in size compared to those of the lateral groups. The radula formula is 3-1-3 with a tricuspoid median plate. Each hook sac has 10 rather short hooks.
The maximum body length is 5 mm.

Juveniles

A special description is not available.

Reproduction

This species is a protandric hermaphrodite.

Ecology

This species is carnivorous.

Distribution

This species appears to be endemic for the Peru and Panama waters, see the Pneumodermopsis polycotyla map. Tesch (1950) believed some records from the Mediterranean and Atlantic southwest off Ireland were correct, but they probably (cf. the synonymy) do not concern this species.

Types

Dexiobranchaea polycotyla Boas, 1886: 161, 224.
Types: Should be present in ZMUC (5 spec.) but were not found. Van der Spoel discovered only two specimens identified by Boas before 1900, without locality data, measuring 6.5 and 8 mm long, which is larger than the largest syntype.
Type locality: Caldera (Chile).

Original description

De parrede Arme er repræsenterede ved c.20 temmelig store Sugeskaale, som hver er forsynet med en tydelig, kort, tynd Stilk og som sidder i en krummet alternerende Dobbeltrække indenfor Mundaabningen (smlgn. Diagrammet p. 158). Den uparrede Arm er kort og bærer en terminal større Sugeskaal. (Diam. omtr. 1-1/2 Gang saa stor som de andre Sugeskaales), samt fire mindre omtrent af samme Størrelse som eller dog kun ubetydelig større end dem, der danner Halvkredsen; af disse fire sidder ét Par tæt ved den store, medens det andet Par sidder tæt ved Armens Grund (men dog paa selve Armen). - Radulas Formel er 3.1.3. Midttanden med en rudimentær Midtspids og to lange Sidespidser. - Hver Krogsæk med en halv Snes temmelig lange Krogtorne. - Gjællen vel udviklet, de to Fimrekranse tilstede, Legemet delvis brunlig pigmenteret. - Største Exemplar 5-mm langt.
Nærværende Art er nær beslægtet med foregaaende, fra hvilken den dog let adskilles navnlig ved det konstant større Antal Sugeskaale, ved det større Antal af Tænder i Radula og at Torne i Krogsækkene, samt ved disse Tornes Form (de er længere end hos paucidens etc.).
Der forelaa af Arten 5 Exemplarer tagne (sammen med D. simplex) vest f. Caldera (Chile) af Ltnt. Chierchia.

Pneumodermopsis polycotyla