Dasyhelea patagonica

Díaz, Florentina, Spinelli, Gustavo R. & Ronderos, María M., 2010, A revision of the species allied to Dasyhelea patagonica Ingram and Macfie (Diptera: Ceratopogonidae), Journal of Natural History 44 (45 - 46), pp. 2825-2849 : 2826-2828

Dasyhelea patagonica group

A group of species characterized by their large size and very dark brown colouration. Sternite 9 of male with posteromedian margin characteristic of each species, with or without posterior projection; gonostylus with two or three mesal setae; parameres symmetrical, well sclerotized, with or without posterior projection; aedeagus with body well sclerotized, posterolateral arms short, recurved. Female flagellum elongated; wing with cubital fork at same level of second radial cell; halter brown; subgenital plate well developed, rectangular or triangular; margin of gonopore well sclerotized; two well-developed spermathecae.

Species included

Dasyhelea dellapei Díaz and Spinelli sp. nov.

Dasyhelea fueguina Díaz and Spinelli sp. nov.

Dasyhelea gargola Díaz and Spinelli sp. nov.

Dasyhelea ona Díaz and Spinelli sp. nov.

Dasyhelea patagonica Ingram and Macfie

Dasyhelea reynoldsi Ingram and Macfie

Dasyhelea shannoni Ingram and Macfie

Taxonomic discussion

The patagonica group is herein proposed on the basis of the combination of characters listed in the diagnosis, all of them poor for consideration as good synapomorphies. If our knowledge of the immatures of the genus is improved then we will hopefully be able to find new, valuable characters to properly propose a phylogenetic classification.

Remm (1971) described the subgenus Sebessia which includes the cincta group, with species in all the mayor biogeographic zones of the World, and the holosericea group, represented by Palaearctic species. The characteristic features of the subgenus are the presence of two well-developed spermathecae, the symmetrical parameres and the ventral surface of the aedeagus covered by a hyaline envelope; the last character being a very good synapomorphy (A. Borkent, pers. comm.; P. Dominiak, pers. comm.). As the Patagonian species lack the aedeagal hyaline envelope, we prefer not to include them within Sebessia .

Key to species

1. Male.................................................................. 2 Female ................................................................ 8

2. Posteromedian margin of sternite 9 with crescent-shaped sclerite followed by two stout, reniform processes............. D. ona Díaz and Spinelli sp. nov. Posteromedian margin of sternite 9 without crescent-shaped sclerite and reniform processes..................................................... 3

3. Posteromedian projection of parameres bearing a stout, distally directed process with broad, bifid tip......... D. fueguina Díaz and Spinelli. sp. nov. Posteromedian projection of parameres without distally directed process with bifid tip................................................................ 4

4. Posteromedian margin of sternite 9 arrow-shaped.. D. shannoni Ingram and Macfie Posteromedian margin of sternite 9 different............................. 5

5. Sternite 9 with trefoil-shaped posteromedian projection; gonostylus with a double curve.............................. D. reynoldsi Ingram and Macfie Sternite 9 without posteromedian projection; gonostylus nearly straight... 6

6. Posteromedian margin of sternite 9 not excavated, broadly rounded; aedeagus with rounded tip; scutellum with 28–30 long setae and 22–28 shorter ones...................................... D. dellapei Diaz and Spinelli sp. nov. Posteromedian margin of sternite 9 with rounded excavation; aedeagus without rounded tip; scutellum with 14–18 long setae and 10–18 shorter ones................................................................... 7

7. Posterolateral margins of posteromedian excavation of sternite 9 broad, truncate; basal arms of parameres stout, with conspicuous laterodistal, pointed processes; aedeagus stout 0.7 times longer than greatest width............................................ D. gargola Díaz and Spinelli sp. nov. Posterolateral margins of posteromedian excavation of sternite 9 pointed; basal arms of parameres slender, without laterodistal processes; aedeagus 0.5 times longer than greatest width......... D. patagonica Ingram and Macfie

8. Subgenital plate very high, triangular...... D. shannoni Ingram and Macfie Subgenital plate low, subtriangular or rectangular........................ 9

9. Subgenital plate with two short, slender processes arising from laterodistal margins of gonopore; spermathecae pyriform........................................................................ D. ona Díaz and Spinelli sp. nov. Subgenital plate without slender processes arising from laterodistal margin of gonopore; spermathecae ovoid......................................... 10

10. Subgenital plate rectangular........................................... 11 Subgenital plate subtriangular......................................... 12

11. Tarsi dark brown; scutellum with 19–20 long setae and 15–16 shorter ones; anterior margin of subgenital plate irregular..................................................................... D. gargola Díaz and Spinelli sp. nov. Tarsi paler; scutellum with 13–16 long setae and 6–8 shorter ones; subgenital plate rounded anteromesally............. D. patagonica Ingram and Macfie

12. Posterolateral arms of subgenital plate slender, inner margin concave with pointed, mesally directed tip........................................... 13 Posterolateral arms of subgenital plate stout, inner margin with bulbous protuberance................................. D. reynoldsi Ingram and Macfie

13. Scutellum with 16–21 long setae and 8–12 shorter ones; spermathecae necks hyaline.............................. D. fueguina Díaz and Spinelli sp. nov. Scutellum with 25–30 long setae and 22–26 shorter ones; spermathecae necks well sclerotized....................... D. dellapei Díaz and Spinelli sp. nov.