Evolution and taxonomy of Andogyrus Ochs (Coleoptera: Gyrinidae)

Abstract

Analysis of relevant structures showed that there are three evolutional lineages in Andogyrus. Two have remained in southernmost South America, near the ancestral area of the genus (probably the Antarctic). One lineage has spread northwards and radiated in the Andes. There is a parallel anagenetic evolution of groups of structures which can be related to adaptation to fast-running water. Cladistic analysis according to Hennig (basic splitting) and Camin & Sokal (specific derivation) led to the division of the genus in seven species groups. A key to species is given and six new species group taxa described: A. viscus, A. bos, A. produetus, A. clypealis, A. buculus and A. colombicus subsp. australis.

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“…Most species of Macrogyrus have nine distinct longitudinal striae, although many have them obscured medially or reduced in number, and many have them absent, especially several species from New Guinea. In their revisions of Andogyrus , Ochs (1954) and Brinck (1977) did not offer any additional features of any diagnostic significance for these two taxa. Other than pointing out differences in size, ‘general aspect' and ‘other minor characters' Ochs (1949a) also did not describe major diagnostic features helping differentiate the two genera in his treatment of Macrogyrus in Australia.…”

“…Together, these two tribes represent the greatest species diversity in Gyrinidae and are well represented in Africa. The other large group, the tribe Enhydrini, was revised in Africa by Brinck (1955) (with the genus Dineutus occuring in Africa), but he did not describe the genitalia of members of this tribe, although later he considered the female genitalia again in his revisions of Enhydrus and Andogyrus (Brinck, 1977, 1978). Structures associated with internal genitalia were found useful by Brinck (1955, 1956, 1977, 1978) for larger groupings of gyrinids and also at the species level.…”

“…The other large group, the tribe Enhydrini, was revised in Africa by Brinck (1955) (with the genus Dineutus occuring in Africa), but he did not describe the genitalia of members of this tribe, although later he considered the female genitalia again in his revisions of Enhydrus and Andogyrus (Brinck, 1977, 1978). Structures associated with internal genitalia were found useful by Brinck (1955, 1956, 1977, 1978) for larger groupings of gyrinids and also at the species level. Despite his commendable and detailed examination of female genitalia in Gyrinidae, his interpretation of structures and terminology was somewhat problematic and potentially subject to reinterpretation (Burmeister, 1990).…”

“…Many of the species historically in Andogyrus were originally described in Macrogyrus (e.g. Régimbart, 1882), and the two groups have had a long history of assumed close affinity (Hatch, 1925; Ochs, 1926–1927, 1949a; Brinck, 1977), but further study is required to determine the status of these two genera. The genus includes about 40 species in Australia and New Guinea which have been placed into a large number of subgenera (Ochs, 1949a), the monophyly of which has not been investigated.…”

“…Taxonomy. The genus includes about 12 species in South America based on a modern revision by Brinck (1977). Only a single species was included in our analysis, and so the monophyly of the group was not tested, although the group is morphologically exceptionally homogeneous.…”