Revision of Synagoga (Crustacea: Maxillopoda: Ascothoracida)

Summary

This paper is a revision of the most primitive genus of the Ascothoracida, Synagoga Norman. The three previously described species, S. mira Norman, 1888 (the type), S. metacrinocola Okada, 1926, and W. sandersi Newman, 1974, are partly redescribed to correct errors and to add new details. A new genus, Waginella gen. nov., is proposed for the latter two species, and the diagnosis of Synagoga is restricted.

Synagoga normani sp. nov. lives on the soft coral Dendronephthya sp. in shallow water near Mombasa, Kenya. It is larger than S, mira and its appendages differ in minor respects. New specimens of W. metacrinicola and W. sandersi from their respective type localities were examined. The major features of S. sandersi's internal anatomy are similar to W. metacrinicola (Okada 1926). Crinoids from S. sandersi's type locality showed no evidence of ascothoracid infestation. The new specimens of W. sandersi were infested with cryptoniscid isopods; a questionable record of the same isopod species suggests that the ascothoracid may have a depth range of 260–5200 m. W. axotremata sp. nov. is very similar to, but smaller than, W. metacrinicola, and lives attached by a cement pad to the cirri of several species of the bathyal stalked crinoid Metacrinus (considered Saracrinus spp. by Roux 1981) in the Philippines and Indonesia. It may be a protandric hermaphrodite. Seminal receptacles are found in species of both genera, so these organs probably originated very early in the history of the Ascothoracida.

Synagoga's range includes the Mediterranean and East Africa; a newly described, Synagoga-like ascothoracid larva from the Caribbean (Grygier 1983 b) implies that the genus' real range may be pan-tropical. If a recent study of the history and biogeography of isocrinid crinoids (Roux 1981) is correct, the sister group of W. metacrinicola and W. axotremata should be found parasitizing the Caribbean crinoid Cenocrinus; if there are no ascothoracid parasites of non-metacrinine crinoids, then Waginella may have only become sessile in the early Cenozoic.

Synagoga spp. and Waginella sandersi are very generalized in many respects, but none is entirely plesiomorphic; no one species is the ‘most primitive’ ascothoracid. Waginella's anteroventral carapace pores and W. axotremata's cement production do not appear to be homologous with similar attributes of cirriped cyprid larvae, so the distant relationship between Cirripedia and Ascothoracida postulated on the basis of comparative spermatology (Grygier 1981 a, 1982), is left unrefuted.