Symplectoscyphus ralphae Vervoort, 1993

Galea, Horia R., 2016, Notes on some sertulariid hydroids (Cnidaria: Hydrozoa) from the tropical western Pacific, with descriptions of nine new species, European Journal of Taxonomy 218, pp. 1-52 : 45-46

Symplectoscyphus ralphae Vervoort, 1993

Fig. 10 M–V

Symplectoscyphus ralphae Vervoort, 1993: 270 , figs 65e–f, 66a–c.

Material examined

NORFOLK 1: Stn. DW1712, two fertile colonies, ca 18 mm high, both detached from substrate (sample A) (MNHN-IK-2012-16594); two colonies, 10 and 20 mm high, the largest bearing two gonothecae (sample B), on bryozoan (MNHN-IK-2012-16595).

Remarks

The trophosomes of both samples are indistinguishable morphologically (compare Figs 10M and 10N; 10O and 10P; 10 Q–R and 10S–T), but the gonothecae they bear are different. Those in sample A are smaller, provided with 12–14 transverse ridges and a narrow, trumpet-shaped distal tube ( Fig. 10U), while those in sample B are comparatively larger, exhibit about 15 ridges, and their distal tube is much wider and has an everted rim ( Fig. 10V). Although the gonothecal content in sample A could not be

confidently ascertained, it may prove to be male; that in sample B contains two large ovoid bodies (either oocytes or developing planulas), and is consequently assigned to the female sex.

Vervoort (1993) did not compare his new species with its congeners, and the present identifications are mainly based on the shape of the gonotheca. However, other symplectoscyphid hydroids belonging to the present collection, but not included in this study, exhibit indistinguishable trophosomes, but their gonothecae are of different sizes and bear a varied number of transverse ridges. Consequently, it is felt that the discrimination of species belonging to certain morphologically related groups of Symplectoscyphus is not possible in the absence of molecular studies, owing to the absence of reliable morphological characters.

Geographical distribution

New Caledonia ( Vervoort 1993), Norfolk Ridge (present study).