Pterognathia ugera Sterrer, 1991

Sterrer, Wolfgang, 2006, Gnathostomulida from the Otago Peninsula, southern New Zealand, Zootaxa 1172, pp. 1-19 : 9-11

Pterognathia ugera Sterrer, 1991

(Fig.Fig. 4.4–4.6)

Material

Four juveniles/anterior fragments from sample SI 16.

Distribution

Tahiti ( Sterrer 1991c), (sub)tropical NW Atlantic ( Sterrer 1998).

Description

Rostrum measurements of this colorless­opaque species were 175–270 µm in length and 45–50 µm in width (index 4.64). The pharynx is 12.67 µm long behind the symphysis. The basal plate, 7.75 µm long and 11.25 µm wide (index 0.70) is horseshoe­shaped, bearing a pair of latero­caudally pointing wings; its rostral rim is entirely set with 25–31 (28.00) very regular teeth. The jaws are compact, 13.75 µm long, with short rostral apophyses and 3–4 teeth. In unsqueezed specimens the basal plate covers the jaws such that the jaw apophyses coincide with the latero­caudal extensions of the basal plate (Fig. 4.5).

Discussion Easily identified by its unique basal plate, this circumtropical species may eventually warrant a separate genus due to its distinctive mouth part architecture ( Sterrer 1998).

Pterognathia portobello n. sp.

(Fig.4.7–4.8)

Type material Holotype one anterior fragment from sample SI 16, in squeeze preparation, NZNM W.1535.

Etymology In appreciation of facilities and help provided during my stay at the Portobello Marine Laboratory, University of Otago, Dunedin, New Zealand.

Diagnosis

Pterognathia with delicate jaws 13 µm long. Basal plate 2 µm long and 14 µm wide (index 0.14), with several rows of many minute teeth over median two thirds of rostral edge.

Description

The only specimen, an anterior fragment, was colorless­translucent, 1350 µm long and 50 µm wide, and had a rostrum 270 µm long and 35 µm wide (index 7.71).

The basal plate is a thin transverse sliver, 2 µm long and 14 µm wide (index 0.14), with pointed lateral tips. The median two thirds of its rostral edge are set with two or more horizontal rows of minute thorn­like teeth. The jaws are 13 µm long and delicate. The narrow symphysis lamellae join posteriorly in a small, globular symphysis. Anteriorly the jaws broaden, but it was not possible to identify distinct features such as rostral apophyses or cristae. Each jaw terminates dorso­rostrally in a knob, and ventro­rostrally seemed to have 4–5 teeth. The pharynx measures 10 µm in length behind the symphysis.

Nothing is known about the reproductive system.

Discussion

A much­wider­than­long basal plate and many­toothed jaws characterize Cosmognathia and Pterognathia . In its ‘front­heavy’ jaw architecture the new species most resembles Pterognathia ugera Sterrer, 1991 . Although the single specimen represents without doubt a new species, the fragmentary and delicate nature of its features suggests leaving the assignment to genus tentative pending an analysis of additional material.