Haplognathia ruberrima (Sterrer, 1966)

Sterrer, Wolfgang, 2006, Gnathostomulida from the Otago Peninsula, southern New Zealand, Zootaxa 1172, pp. 1-19 : 7-9

Haplognathia ruberrima (Sterrer, 1966)

(Fig.3.7–3.8)

Material Three juveniles/anterior fragments from sample SI 16.

Distribution

North Sea, Adriatic ( Sterrer 1969), Canary Islands ( Sterrer 1997), (sub)tropical NW Atlantic ( Sterrer 1998), Fiji ( Sterrer 1991a), Hawaii ( Sterrer 1991b), NE Australia ( Sterrer 2001).

Description

Body bright crimson. Basal plate more or less hexagonal, 5.67 µm long, 8.00 µm wide (index 0.71), with rows of thorns on its dorsal surface. Jaws 20.00 µm long, with one pair of teeth and with relatively long, straight rostral apophyses (apophysis index 0.50).

Discussion

Sterrer (1998) discussed the cosmopolitan distribution, variability, frequent sympatry, and possible tendency of H. ruberrima and H. rosea to hybridize. The two species are nevertheless fairly distinguished by jaw apophysis index (0.50 or more in H. ruberrima , 0.50 or less in H. rosea ) and details of the basal plate (with dorsal thorns in H. ruberrima , without thorns but with longitudinal ridges in H. rosea ).

Family Pterognathiidae Sterrer, 1972

Pterognathia sica Sterrer, 2001

(Fig.4.1–4.3)

Material Two juveniles from sample SI 16.

Distribution NE Australia ( Sterrer 2001).

Description

Colorless­translucent. The larger of the juveniles was 1150 µm long and 45 µm wide (index 25.5), with a rostrum 150 µm long and 30 µm wide (index 5.00). Neither of the two specimens had a basal plate. The jaws are slender, and 18 µm long in both specimens; with long, curved rostral apophyses, dorsal cristae, and a small, transverse­oval symphysis. There are 5 long, ventral teeth and 3–4 shorter dorsal teeth.

Discussion

Although the jaws of the NZ specimens are considerably shorter than those of Australian specimens (26.00 µm), they otherwise agree well with the original description of P. sica , the only known species in the genus Pterognathia that consistently lacks a basal plate.