Ophirodexia Townsend, 1911

de Santis, Marcelo Domingos, 2021, A review of Ophirodexia Townsend, 1911 (Diptera: Tachinidae), Journal of Natural History 55 (3 - 4), pp. 151-161 : 152-154

Genus Ophirodexia Townsend, 1911

Ophirodexia Townsend, 1911: 134 (also, 1912: 307). Type species: Ophirodexia pulchra Townsend, 1911 (by monotypy).

Tromodesiopsis Townsend, 1927: 221 . Type species: Tromodesia haemorrhoidalis Bigot (by original designation) = T. atrifrons (Wiedemann) . syn. nov.

References. Townsend 1936: 27, 29 (diagnosis of adults and immatures of Zeliini , including Ophirodexia and Tromodesiopsis ); Townsend, 1939: 81, 85 (redescriptions of Ophirodexia and Tromodesiopsis ); Guimarães (1971: 101; 102, catalogue); Evenhuis et al. (2015: 194; 271, catalogue of Townsend’s genera); O’Hara and Henderson (2020: 60; 82, world checklist of tachinid genera); O’Hara et al. (2020: 54; 77, list).

Included species

Ophirodexia pulchra Townsend, 1911: 134 (also, 1912: 308). Holotype female (USNM) not seen: Peru, Piura. A male from Townsend’s (1912) description that is deposited at the NHM-UK was examined.

Ophirodexia atrifrons ( Wiedemann, 1830: 403) – ( Musca ). Holotype female (NHMW) not seen: locality unknown. comb. nov.

Tromodesia haemorrhoidalis Bigot, 1889: 267 – ( Tromodesia ). Holotype male (NHM-UK) seen: ‘Mexico’

Ophirodexia semirufa ( van der Wulp, 1891: 250) – ( Leptoda ). Holotype male (NHM-UK) seen: Mexico, N. Yucatan, Temax. comb. nov.

On the generic status of Zelia and Ophirodexia

Of the nine genera placed in the ‘Zeliini’, six very closely resemble Zelia : Diaugia Perty, 1833 ; Huascarodexia Townsend, 1919 ; Neozelia Guimarães, 1975 ; Taperamyia Townsend, 1935 ; Ushpayacua Townsend, 1928 ; Yahuarmayoia Townsend, 1927 . All of these genera are monotypic except for Zelia and most, if not all, may be synonymous with Zelia . As a confirmation of this view, while conducting a taxonomic revision of the genus Opsozelia Townsend, 1919 , another genus that also very closely resembles Zelia, Dios and Santis (2019) formally synonymised it with Zelia .

The genus Ophirodexia can be distinguished from Zelia and its closely related genera by following the diagnostic key. The male with pulvilli and claws shorter than the fifth tarsomere is the most fascinating trait found only in Ophirodexia . Tromodesiana Townsend, 1931 , a former member of ‘Zeliini’, differs from all other genera of this former tribe by having setulae on both the prosternum and propleuron; a setulose prosternum is a very rare trait in Dexiinae , being present in some species of Ebenia Macquart, 1846 (Dufouriini) , but in no other Dexiini . Recently, O’Hara et al. (2020) considered Tromodesiana an unplaced Tachinidae . Thus, regarding the above evidence and discussion, it is quite likely that Tromodesiana does not pertain to Dexiini , and its placement in Dexiinae is doubtful.

Finally, following the generic diagnosis given herein, Tromodesiopsis atrifrons was considered to fall within the generic delimitation of Ophirodexia . Tromodesiopsis presents the main traits found only in Ophirodexia (e.g. width of parafacial 0.8–0.9× the width of gena, genal dilation undeveloped, male with pulvilli and claws shorter than fifth tarsomere and abdomen cylindrical, with syntergite 1 + 2 with a pair of marginal median setae) and does not present the traits of Zelia (e.g. width of parafacial 0.5× the width of gena, genal dilation is developed, male with pulvilli and claws longer than fifth tarsomere, and the abdomen is somewhat ovate, not cylindric, with the syntergite 1 + 2 without a pair of marginal median setae); thus, it is generically different from Zelia but not from Ophirodexia , supporting this new combination.

Diagnostic key for Zelia and Ophirodexia

Only Zelia is keyed in the Manual of Central American Diptera , in the key for Tachinidae ( Wood and Zumbado 2010) . However, Ophirodexia keys to Zelia in couplet 177 (p. 1383) of the manual and can be separated from Zelia using the following diagnostic key.

Ocellar seta weak. Frontal vitta at its widest point approximately as wide as the vertex in dorsal view. Frontal vitta at its narrowest point smaller than the width of the ocellar triangle. Width of parafacial measured between inner margin of compound eye and antennal insertion is 0.8–0.9× the width of gena in lateral view. Genal dilation undeveloped. Male with pulvilli and claws short, shorter than fifth tarsomere. Abdomen cylindrical. Syntergite 1 + 2 with a pair of marginal median setae. Tergite 3 with 2–3 equal-sized pairs of discal setae... Ophirodexia Townsend, 1911

Ocellar seta strong. Frontal vitta at its widest point approximately 2× as wide as the vertex in dorsal view. Frontal vitta at its narrowest point the same width as the ocellar triangle. Width of parafacial measured between inner margin of compound eye and antennal insertion is 0.5× the width of gena in lateral view. Genal dilation developed. Male with pulvilli and claws long, longer than fifth tarsomere. Abdomen somewhat ovate, not cylindrical. Syntergite 1 + 2 without a pair of marginal median setae. Tergite 3 with 0–3 pairs of discal setae that increase its length posteriorly... Zelia Robineau-Desvoidy, 1830

Key to species of Ophirodexia Townsend, 1911

1 – Syntergite 1 + 2 to tergite 4 brownish black, without median brown longitudinal vitta

( Figure 1 (a,c)); silver pruinosity covering almost all tergites; tergite 5 reddish brown apically ( Figure 1 (c)) ........................ ........................ O. atrifrons (Wiedemann, 1830) comb. nov.

- Abdomen mostly dark yellow or tawny yellow, with uninterrupted median brown longitudinal vitta on syntergite 1 + 2 to tergite 4; silver pruinosity covering at most half of tergites 3 and 4 ...................................................................................................................... 2

2 – Abdomen reddish yellow in ground colour ( Figure 2 (a,c)); scutellum silvery pruinose; leg brownish black, but femur silver pruinose................................................................................. ................................................................................. O. semirufa ( van der Wulp, 1891) comb. nov. - Abdomen tawny yellow in ground colour ( Figure 3 (a,c)); scutellum without pruinosity;

leg tawny yellow, but tibia darker ............................................ O. pulchra Townsend, 1911

Figures

Figure 1. Tromodesia haemorrhoidalis Bigot, 1889 (= Ophirodexia atrifrons Wiedemann, 1830) holotype ♂. (a) Dorsal habitus. (b) Head, frontal view. (c) Lateral habitus. (d) Labels.

Figure 2. Ophirodexia semirufa (van der Wulp), holotype ♂. (a) Dorsal habitus. (b) Head, frontal view. (c) Lateral habitus. (d) Labels.

Figure 3. Ophirodexia pulchra Townsend ♂. (a) Dorsal habitus. (b) Head, frontal view. (c) Lateral habitus. (d) Labels.