Miscellanea Zoologica Hungarica 11. 1997 (Budapest, 1997)

Hołyńska, M.: A new representative of Mesocyclops thermocyclopoides-circle (Copepoda: Cyclopoida) from India

unite M. thermocyclopoid.es Harada, 1931, M. isabellae Dussart & Fernando, 1988, M. dussarti Van de Velde, 1984 and M. dadayi sp. n. in a subgroup [I have no information of these features in M. arcanus Defaye, 1995, M. notius Kiefer, 1981, and M. australiensis (Sars, 1908)]. Among the Old-World Mesocyclops not belonging to the Thermocyclopoides-ckcle and known to me (M. ruttneri Kiefer, 1981, M. papuensis Van de Velde, 1987, M. splendidus Lindberg, 1943, M. pseudoannae Van de Velde, 1987, M. pehpeiensis (Hu, 1943), M. leuckarti (Claus, 1857), M. salinus Onabamiro, 1957, M. paludosus Lindberg, 1956, M. rarus Kiefer, 1981, M. spinosus Van de Velde, 1984, M. darwini Dussart & Fernando, 1988, M. brevisetosus Dussart & Sarnita, 1987, and M. major Sars, 1927), the only species having hairy pediger 5 and genital double somite is the African M. major Sars, 1927, but there these features very probably are homoplasies. These observations suggest, that the characters in question appeared in the common ancestor of M. thermocyclopoides Harada, 1931, M. isabellae Dussart & Fernando, 1988, M. dussarti Van de Velde, 1984 and M. dadayi sp. n. Within the quartette, M. isabellae Dussart & Fernando, 1988, M. dussarti Van de Velde, 1984, and M. dadayi sp. n. are connected by a less spectacular feature: transversal rows of spinules, occurring in all the other species of the Thermocyclopoides-ckcle on the 1. 4-5. 713. antennular segments only, are present in these three species on the 14. antennular segment also. To be sure, I could also observe spinules on the 14. antennular segment in some specimens of M. woutersi Van de Velde, 1987 (Papua New Guinea: Madang Pr.) M. dissitnilis Defaye & Kawabata, 1993 (Japan: Lake Biwa and Lake Kitaura) and M. aequatorialis similis Van de Velde, 1984 (Ethiopia: Lake Awassa), but in fixed state this character is exlusivcly confined to M. isabellae Dussart & Fernando, 1988, M. dussarti Van de Velde, 1984, and M. dadayi sp. n. In those Palaeotropical Mesocyclops species, which do not belong to the Thermocyclopoides-ckcle, this feature in fixed state is never present. To resolve the relations within this triad, the autapomorph characters and their alternates as synplesiomorphies had to be exluded from the analysis. The banded pore canal in M. dadayi sp. n. is a unique feature I have not seen in other Old-World Mesocyclops. Features, which are unique within the Thermocyclopoides-ckcle, as hairs on the caudal surface of leg 4 intercoxal sclerite in M. dadayi sp. n., and caudal hairs near medial rim of leg 4 coxa in M. dussarti Van de Velde, 1984 also appear in outside of the circle - the former feature in M. major Sars, 1927, M. salinus Onabamiro, 1957 and M. tenuisaccus (Sars, 1927), the latter one in M. major Sars, 1927 and M. tenuisaccus (Sars, 1927) -, therefore I reckon the presence of these characters among homoplasies, and their absence among symplesiomorphies in the group studied. Although hairs on medial surface of the furca are present in two other representatives of the Thermocyclopoides-ckcle [M. aspericornis (Daday, 1906)- at full length; M. microlasius Kiefer, 1981- in the proximal half], I think it is more likely that they are non-homologous features evolved independently in the three species: differences in the position of the copulatory pore and its connection with transverse ducts (female genital system), hair ornamentation on dorsum of the pediger 5 and genital double somite, and in the spinule ornamentation of 14. antennular segment suggest that those species can not be united with M. dadayi sp. n. in a monophyletic group. I consider the completely haired dorsum of the genital double somite of M. dussarti Van de Velde, 1984 vs. the partly (in the proximal halt) haired genital double somite of M. dadayi, M. isabellae Dussart & Fernando, 1988 and M. thermocyclopoides Harada, 1931 as autapomorphy, too. The genital double somite, fused from 7. thoracic (genital) and 1. abdominal segment, is entirely naked in other representatives of the Thermocyclopoides-ckcle, and only in M. major Sars, 1927 - a species outside the circle - it is at full length hairy. It seems likely, that the hairiness of the genital dou-