Desmopterus gardineri Tesch, 1910a
Overview
This is a completely shell-less pteropod, very small in size since the swimming disc diameter is only 0.5 cm. The wings are disc-shaped and transparent except for numerous muscle fibres. The visceral mass forms an opaque appendix curved around the swimming disc. Besides the median lobe the disc has two short tentacles. There is no separate proboscis. It is an elegant swimmer that feeds with a mucous web on microplankton. It lives in the warm waters of the Indian Ocean (Desmopterus gardineri).
Taxonomic Description
The general shape is similar to Desmopterus papilio. The anterior parts are perpendicular to the axis of the posterior trunk, and to the wing plate. The pallial gland is strongly reduced. Red unicellular glands are found on the thin transparent integument. The gland cells are smaller than those in the preceding species. The musculature of the swimming plate is the most significant character of the species. The muscle bands run in two directions which is normal for this genus, however,the number of muscle bands is reduced compared to Desmopterus papilio and the bands are broader and more clearly separated. The number of muscle bands in Desmopterus papilio is about twice that in Desmopterus gardineri. The number of muscle fibres forming the bands is, however, similar in both species.
The diameter of the swimming plate is 5 mm.
Juveniles
A special description is not available.
Reproduction
This species is a protandric hermaphrodite.
Ecology
This species is phytophagous and epipelagic.
Distribution
This species is endemic to the Indian Ocean and occurs throughout this ocean. In comparison to Desmopterus papilio, it is less abundant which explains the more patchy character of the map, see the Desmopterus gardineri map. The few records of this species in the Atlantic Ocean (Wormelle, 1962; Haagensen, 1976) concern expatriates as also found for Cavolinia globulosa.
Types
Desmopterus gardineri Tesch, 1910a: 168, pl. 12, figs. 1-3.
Holotype: the single spec. could not be found u.s.
Type locality: 4°16'S 71°53°E. COh: CPSE.