Thereus Huebner , [1819]

Robbins, Robert K., Heredia, Maria Dolores & Busby, Robert C., 2015, Male secondary sexual structures and the systematics of the Thereusoppia species group (Lepidoptera, Lycaenidae, Eumaeini), ZooKeys 520, pp. 109-130 : 112-113

Taxon classification Animalia Lepidoptera Lycaenidae

Thereus Huebner, [1819]

Type species.

Papilio lausus Cramer

Diagnosis.

Robbins (1991) characterized Thereus by (1) a pair of sclerotized invaginations on the membrane attached to the ventro-lateral sides of the papillae anales (Figs 23-24, figured in Robbins 2000), (2) a pair of ventro-lateral brush organs (often inconspicuous) in addition to the pair of dorsal ones (Figs 15-18), and (3) the number of antennal nudum segments (as defined in the methods section) is sexually dimorphic, being greater in females than that in males by five or more segments (Fig. 25). The second trait is lacking in Thereus pseudarcula (Giacomelli), suggesting that this species is the phylogenetic sister to the remainder of the genus. Interestingly, it is the only Thereus species that appears to be a subtropical endemic. During this study, we found an instance in which sexual dimorphism of antennal nudum length was four segments-not five or greater-so the generic diagnosis is modified accordingly.

Robbins (1991) noted that Thereus contained 27 species, but more than a decade later, 31 were listed, of which nine were undescribed and two had questionable generic placement ( Robbins 2004). Bálint (2005) proposed a new specific name, and we now recognize 35 species, of which eleven are undescribed and two have questionable generic placement. This paper begins the task of recognizing species groups, which facilitates the description of new species, and of determining the generic placement of the species with questionable generic placement.

Nomenclature.

Robbins (1991) accorded Thereus Hübner priority over Molus Hübner and synonymized Noreena K. Johnson, MacPherson & Ingraham. Subsequently proposed names Solanorum Johnson, Timokla Johnson, Kruse & Kroenlein, and Pedusa d’Abrera were synonymized later ( Robbins 2004).

Distribution.

Thereus occurs throughout the Neotropics from northern Mexico to Uruguay and Argentina. Thereus lausus , Thereus cithonius , and Thereus ortalus range widely from Mexico to southern Brazil, but distributions of species are otherwise more restricted. Approximately 2/3 of the species in the genus occur in the Amazon Region, as demarcated by Brown (1982).

Habitat.

Most species inhabit wet lowland forest, with only a few exceptions. Thereus gabathana (Strand), Thereus wojtusiaki Bálint, Thereus orasus (Godman & Salvin), and an undescribed species are montane endemics, and Thereus pseudarcula is subtropical. The widespread Thereus cithonius occurs in a great variety of habitats, from wet forest to very dry deciduous forest and from sea level to 2,000 m elevation.

Biology.

Heredia and Robbins (in prep.) summarize the food plant records for the genus, almost all of which belong to the plant family Loranthaceae (mistletoe). As noted in this paper, males of some species set up mating territories in the morning before 09:30 hours while others set up territories in the early afternoon.