Corethrella

Published, First, 2008, The Frog-Biting Midges of the World (Corethrellidae: Diptera), Zootaxa 1804, pp. 1-456 : 26-28

Corethrella names of uncertain status

A few species of Corethrella are missing types or are represented by type material in terrible condition. These are discussed as follows.

Corethrella maculata was described by Lane (1939a:104) from a single male from Iquitos, Peru and subsequently ( Lane 1953:76) noted a second specimen from Santiago, Cuba. The holotype (DEFS) is represented by a collapsed head capsule (without antennae or palpi) and thorax (with only one hind femur and a basal half of one wing) mounted on one slide and a badly damaged male genitalia on a second slide. The male from Cuba (USNM), which Lane considered to be conspecific with the holotype, is in moderate condition. However, the male genitalia of this specimen had been mounted earlier on a piece of clear plastic and is very distorted. The remainder of the specimen is either bleached or teneral and was difficult to study.

The female holotype of C. striata Lane (DEFS) was similar to C. incompta (see under that species) but was unfortunately missing its antennae so that it could not be confidently interpreted. Lane (1942) described a paratype female which I was unable to locate. If found, it may allow for the accurate identification of C. striata .

Corethrella shannoni Lane (1939a:104) was originally described from five male and three female adults reared from larvae collected from a swamp at Iquitos, Peru. Lane and Cerqueira (1958) described the larvae and pupae from Manáos, Amazonia, Brazil and placed the species in Lutzomiops , recognizing the distinctive pupal respiratory organ of this group of species (and therefore a member of what is here called the peruviana species group). The holotype was reported by Lane (1953) and Belkin et al. (1968) to be in the USNM but apparently is not there anymore. Lane (1939a, 1953) states that all femora and tibiae and the first tarsomeres of the fore- and midlegs are dark brown. This is a unique combination of features for a species in the peruviana species group.

Corethrella barrettoi Lane (1942:132) is known only from the holotype male and one paratype male from Casa Grande, São Paulo, Brazil. The type material, stated to be in the DEFS, is missing and this species cannot, therefore, be confidently recognized. Lane (1953:100) recognized it as a Lutzomiops , here identified as the peruviana species group, and his description of the male genitalia, with two strong setae (here = dorsomedial setae) on a sclerotized plate and an “expanded seta which is foliaceous at apex” (here = part of the dorsal row), confirms that C. barrettoi belongs to this species group. However, his description of the males as having a scutum (his mesonotum) with three stripes and legs entirely yellowish is unique within this species group. Rediscovery of the types or fresh collections of specimens from the type locality matching this description are needed to further interpret this species. It is uncertain how the specimens were originally collected.

Corethrella stonei Lane (1942:119) is known only from a single male holotype (USNM). It was collected at Porto Bello Bay, Caldera Island, Panama (no date of collection) by A.H. Jennings and has a label stating “caught at crab holes”. Lane (1953:89) mentioned that the holotype was captured in crab-holes made by Cardisoma spp. , but it is uncertain how he knew the crab’s genus. The specimen has a well-developed midlength wing band, the apical 0.4 of the midfemur paler, and the base of the hind tibia is without pigmentation. The specimen is close to C. badia but the abdomen is mostly missing and the genitalia badly distorted, making its identification uncertain. The antenna of the holotype is very pale, with only the basal half of flagellomere 1 more darkly pigmented, making it distinctive within that group of species with only the basal portion of the hind femur and the apical portion of the hind tibia with dark pigmentation. The specimen was originally on a pin, with the genitalia mounted on a celluloid strip, but all parts are now mounted on one microscope slide.

Corethrella whitmani Lane (1942:108) was described from a holotype female, two female paratypes and at least one pupa and larva (the latter possibly exuviae), collected from Estado do Espírito Santo (VIII-1940) and Juquiá, São Paulo (XII-1939) Brazil. Belkin et al. (1971:29) restricted the type locality to Sao Joao de Petropolis, Espírito Santo. Although the type specimens should be in the DEFS, they are apparently now missing. The description of the adults by Lane (1942, 1953) is insufficient to identify this species and it is presently uncertain whether the immature stages are conspecific with the adults. Lane and Cerqueira (1958) reared 18 specimens from larvae collected from ground pools and bromeliads. These specimens were not reexamined here and cannot be confirmed, but the different larval habitats suggest the presence of more than one species (see “Habitat Diversification of Immatures”). Snow (1949) recorded C. whitmani from Guatemala, rearing these from “a large bamboo internode”, but the specimens appear to be lost and the identification could not be confirmed.

There are four species of Corethrella reported from Japan: C. nippon , C. urumense , C. towadensis and C. japonica . Corethrella nippon is the only species in that country with a plain wing. The remaining three species have a midlength wing band and are quite similar to one another. Unfortunately, C. towadensis and C. japonica are known only from their original descriptions and their types are lost. Miyagi (1980) considered it likely that the two species are conspecific but there appear to be significant differences based on the original descriptions (see under C. towadensis ). Corethrella towadensis was described in sufficient detail to include it in the key to the species from the Palaearctic and Oriental Regions, and a description extracted from the literature is given below. Corethrella japonica is too poorly known to include. Should fresh specimens of both of

these nominal species become available (especially through collecting at the type localities) it would be worthwhile comparing them to each other and to those of C. urumense . Corethrella japonica is known only as females and C. towadensis only as males, pupae and larvae. The following are adult features that purportedly separate these three species. Miyagi (1980) discusses some additional differences between the larvae of C. urumense and C. towadensis .

C. japonica (based on Komyo 1954)

- scutum dark brown, patterned with “pair of large median brown vittae on cephalic

half and a pale large area on anterior part of caudal half and six pairs of small whitish

pale brown spots around median pale brown markings”.

- midlength band, continuous from anterior to posterior wing margin (dark scales

present on all wing veins)

C. towadensis (based on Okada and Hara 1962)

- scutum dark brown with three pairs of longitudinal stripes of pale yellowish long

hairs.

- midlength band, continuous from anterior to posterior wing margin (dark scales

present on all wing veins)

-gonostylus longer than gonocoxite

- dorsal row of setae on gonocoxite with 8 setae

C. urumense (specimens studied here and character states taken from Miyagi, 1980)

- scutum dark brown with some gray pollinosity

- midlength band, not continuous from anterior to posterior wing margin (dark scales

not present on R 4+5)

- gonostylus shorter than gonocoxite

- dorsal row of setae on gonocoxite with 6 setae

DERIVATION OF GENERIC EPITHET: The name Corethrella (korethron in Greek) means "little brush" and may refer to the overall setose body of the adults of the type species C. brakeleyi .

KEYS TO ADULTS

In the following keys, I have tried to use, as much as possible, character states that are shared by males and females. Most presently unknown males or females will likely key to the correct or at least to very near the correct species. Readers should be mindful that it is very likely that many species of Corethrella remain to be discovered and named.

The definition of some characters and their examination is given in “Materials and Methods”, and readers are encouraged to read these carefully.

Because the distributions of most Corethrella species are so poorly known, I have conservatively included some species in regional keys when these are known only from extralimital but relatively nearby localities (e.g. Indo-Malaysia species are included in both the Oriental and Australasian key). In addition, because there are only a few species in Canada and the United States, I have included a separate key to those species. However, if future work discovers further species in the Nearctic, the reader should use the more inclusive key to all species in the New World.