Cyclopoid Copepods Parasitic in Holothurians in Madagascar

Abstract

Three species of poecilostome copepods are reported as endoparasites of holothurians in the vicinity of Nosy Be in northwestern Madagascar. Two of these belong to a new genus, Calypsarion, for which the type species is C. (= Scambicornus) carinatum (Stock, 1968). Calypsarion leprum sp. n. occurs in Actinopyga miliaris, A. lecanora, and A. mauritiana. Calypsarion sentosum sp. n. lives in Bohadschia marmorata. Lichothuria mandibularis Stock, 1968, redescribed, inhabits Holothuria scabra, H. aff. fuscopunctata, Argiodia nobilis, and Ludwigothuria atra. Several genera of cyclopoid copepods are known as endoparasites of holothurians. Two of these genera, Allantogynus Changeux, 1958, and Cucumaricola Paterson, 1958, are only distantly related to the copepods from Madagascar which are described below. [Synaptiphilus Canu and Cuenot, 1892, although found in the esophagus of holothurians (Bocquet and Stock, 1957), lives also on the integument, and is probably not to be regarded as endoparasitic.] Five poecilostome genera which belong to the Paranthessius group of Stock (1968), and which are thus related to the new genus described below, live in holothurians. These are Synapticola Voigt, 1892, Lecanurius Kossmann, 1877; Diogenidium Edwards, 1891; Diogenella Stock, 1968; and Lichothuria Stock, 1968. Until now only one endoparasitic copepod, Lecanurius kossmannianus, described by Humes (1968) from Actinopyga lecanora (Jaeger) and A. miliaris (Quoy and Gaimard), has been reported from holothurians in Madagascar. MATERIALS AND METHODS Although copepods which live externally on the integument of holothurians may be easily obtained by rinsing the host in weakly alcoholized seawater, the recovery of endoparasitic forms is much more difficult. If the holothurians are split open along their length and the entire body and viscera rinsed, the resulting sediment contains so much mucus and debris that finding the copepods is uncertain. We have found it is best to work with freshly collected holothurians while still in the field. The oral end is slit open for about 6 cm and the host is rinsed quickly in a pail of approximately 3% ethyl alcohol in seawater, at the same time making sure that none of the fluid escaping Received for publication 27 March 1969. from the body cavity of the host is lost. This method avoids contamination with mucus, sand, and bits of tissue, and yields the greatest number of endoparasitic copepods. Differences in the technique of collection may account for the wide variation in the relative numbers of copepods recovered from the groups of hosts listed below. The copepods were studied according to the method described by Humes and Gooding (1964). All measurements were made from specimens in lactic acid, and the body lengths do not include the setae on the caudal rami. In the spine and setal formulas of legs 1 to 4 the Roman numerals indicate spines and the Arabic numerals represent setae. The lengths of the segments of the first antenna have been measured along their posterior nonsetiferous margins. All figures have been drawn with the aid of a camera lucida. The letter after the explanation of each figure refers to the scale at which it was drawn. Measurements in the following descriptions are in microns unless otherwise indicated.