Peraclis apicifulva Meisenheimer, 1906a
Overview
This is a pelagic snail with a left coiled shell, 0.4 cm high; it has 4 whorls and a deep suture with radial crests. The spire is not high. The keel does not end into an aperture tooth. The aperture is wide, the base of the aperture is pointed towards the keeled rostrum. The shell sculpture is sometimes composed of a irregular reticulum, it consists of fine rows of tubercles arranged in spiral lines forming a reticulate pattern on the upper half of the body whorl. The wings are fused into a swimming plate. This species lives usually at great depths in all oceans (Peraclis apicifulva).
Taxonomic Description
The rather elongate shell consists of four whorls separated by a deep suture. The spire is rather high due to the rapid increase in size of the whorls. A keel is found on the whorls but an aperture tooth is absent. Radiating crests are developed between keel and suture, their size decreasing from aperture towards the apex. These crests are ridges on the whorl attached to the preceding whorl with broad bases. The large aperture shows a rounded outer border, the upper aperture border is tilted slightly towards the apex, the lower margin points to the rostrum. This rostrum has a very well developed columellar membrane. Tesch (1946) described transverse striae on the rostrum. The shell sculpture consists of fine rows of tubercles arranged in spiral lines forming a reticulate pattern, on the upper half of the body whorl and interrupted lines may give a "reticulate impression" on the lower half. The shell is white near the aperture and dark red near the apex. The operculum has 6 whorls without radial striation.
Shell measurements: height up to 4.0 mm; maximum diameter up to 3.3 mm.
Juveniles
The juveniles have a small left coiled shell. A special description is not available.
Reproduction
This species is a protandric hermaphrodite.
Ecology
This species is phytophagous and mesopelagic.
Distribution
It is a cosmopolitan, mesopelagic species with a distribution similar to Peraclis reticulata, see the Peraclis apicifulva map. The records are, however, too few to permit more detailed conclusions. Absence of this species in halostazes and in upwelling areas do not prove that this is a real phenomenon as records are absent from other areas. The north-south range in the Atlantic Ocean seems smaller than for Peraclis reticulata. In the Mediterranean and Indian Ocean it is very rare. The records of the synonymous species Peraclis brevispina are given separately, see the Peraclis brevispina map.
Types
Peraclis apicifulva Meisenheimer, 1906: 122, pl. 6, fig. 7.
Syntypes: HMEB 56726, 7 spec. in bad condition (alcohol collection) (Dr. Kilias in let.), the other spec. was lost.
Type locality: 27°30'S 3°7'E, 0°39'N 18°57'W, 17°N 30°W, 21°N 32°W. Coll.: CDSE stat. 1 9-VIII-1903; stat. 26-1X- 1903 ; stat. 9-X- 1903); stat. 1 3-X-1903.
Peraclis brevispira Pelseneer, 1906: 146, pl. 12, figs. 45-49.
Types are absent from the BMNH, only the label is left.
Type locality: Bay of Biscay, CRHE stat 34b stat 36e, stat 27a.