Genus Zelia Robineau-Desvoidy, 1830

Zelia Robineau-Desvoidy, 1830: 314 . Type species: Zelia rostrata Robineau-Desvoidy, 1830 [= Dexia vertebrata Say, 1829] (by subsequent designation of Coquillett, 1910: 621).

Diaugia Perty 1833: 187 . Type species: Diaugia angusta Perty, 1833 (by monotypy). Syn. nov.

Huascarodexia Townsend, 1919a: 176 . Type species: Huascarodexia pulchra Townsend, 1919a (by original designation). Syn. nov.

Leptoda Wulp, 1885: 196 . Type species: Dexia gracilis Wiedemann, 1830 [= Dexia vertebrata Say, 1829] (by subsequent designation of Wulp, 1891c: 250).

Melaleuca Wulp, 1891a: 213 . Type species: Melaleuca spectabilis Wulp (by subsequent monotypy of Wulp, 1891b: 247).

Metadexia Coquillett, 1899: 220 . Type species: Metadexia tricolor Coquillett, 1899 (by monotypy).

Euzelia Townsend, 1915: 23 . Type species: Zelia wildermuthii Walton, 1914 (by original designation).

Minthozelia Townsend, 1919b: 556 . Type species: Minthozelia montana Townsend, 1919 (by original designation).

Opsozelia Townsend, 1919b: 557 . Type species: Opsozelia discalis Townsend, 1919 [= Musca lateralis Fabricius, 1805] (by original designation).

Yahuarmayoia Townsend, 1927: 228 . Type species: Yahuarmayoia analis Townsend, 1927 [= Dexia potens Wiedemann, 1830] (by original designation). Syn. nov.

Ushpayacua Townsend, 1928: 145 . Type species: Ushpayacua ureophila Townsend, 1928 (by original designation). Syn. nov.

Taperamyia Townsend, 1935: 223 . Type species: Taperamyia pickeli Townsend, 1935 (by original designation). Syn. nov.

References: Wulp (1891c: 250, revision of Central American species of Leptoda); Coquillett (1910, type species of: 559, Leptoda; 568, Metadexia and 621, Zelia); Townsend (1919: 182, Leptoda as synonym of Zelia); Aldrich (1929: 1, taxonomic notes on Zelia, synonymy); Townsend (1936: 27, diagnosis of adults and immatures of “ Zeliini ” including Diaugia, Huascarodexia, Metadexia, Euzelia, Minthozelia, Opsozelia, Taperamyia, Ushpayacua, Yahuarmayoia and Zelia); Townsend (1939, redescription of: 78, Diaugia; 78, Euzelia; 79, Huascarodexia; 79, Metadexia; 80, Minthozelia; 81, Opsozelia; 83, Taperamyia; 86, Ushpayacua; 87, Yahuarmayoia and 88, Zelia); Reinhard (1946: 52, revision of Minthozelia); Guimarães (1971, catalogue of Neotropical Tachinidae: 101, Diaugia; 101, Huascarodexia; 101, Metadexia; 101, Opsozelia; 102, Taperamyia; 102, Ushpayacua; 102, Yahuarmayoia and 102, Zelia); Tschorsnig (1985: 55, description of male terminalia of Dexiini, including Diaugia); Wood (1987, 1249: Zelia in key to Nearctic genera of Tachinidae; Minthozelia and Metadexia as synonymous with Zelia); O’Hara & Wood (1998: 755, 756, synonymy and new combinations by Wood, 1987); Ziegler (1998: 172, puparia and cephaloskeleton skeleton of third instars of “ Zeliini ”); O’Hara & Wood (2004: 37, catalogue of Nearctic Tachinidae); Wood & Zumbado (2010: 1383, Zelia in key to Central American Tachinidae; 1414, comments about distribution and hosts); Nihei & Pavarini (2011: 23, revision of Diaugia); Dios & Santis (2019: 113, revision of Opsozelia in synonymy with Zelia); Stireman et al. (2019, phylogenetic analysis); Santis (2021: 153, discussion on the validity of “ Zeliini ” genera; Zelia in a diagnostic key); O’Hara & Henderson (2020, world checklist of tachinid genera: 24, Diaugia; 38, Huascarodexia; 73, Taperamyia; 78, Ushpayacua; 80, Yahuarmayoia and 81, Zelia); O’Hara et al. (2020, checklist of World Tachinidae: 42, Diaugia; 52, Huascarodexia; 78, Taperamyia; 83, Ushpayacua; 84, Yahuarmayoia and Zelia); Nihei et al. (2022: 8, description and illustration of the antenna of Zelia sp.); Santis (2022: 303, Zelia in key to the Zelia group of genera).

Recognition. Medium to large tachinids, with head bearing fronto-orbital plate with silver pruinosity, whereas in some species the dorsal region is yellowish and parafacial bare; thorax usually blackish with silvery pruinosity forming four dark vittae on prescutum, wing usually hyaline but sometimes smoky, abdomen conical to broad, usually yellowish, reddish or blackish, with silvery pruinosity laterally and dorsally.

Zelia was distinguished from other genera of Central American Tachinidae in the key of Wood & Zumbado (2010). These authors also noted that the genus consists of “more than 20 nominal species south of the USA, some now in other genera” (Wood & Zumbado 2010: 1414). Later, Dios & Santis (2019) provided diagnoses for both Dexiini and Zelia that distinguishes the tribe within Tachinidae and the genus within the tribe. Santis (2022) gave a key that included Zelia and allied genera of Dexiini; i.e., the Zelia group and Dolichozelia Santis, 2022 .

The key in Wood & Zumbado (2010: 1383) can be modified as follows to accommodate our new and expanded concept of Zelia:

174. Wing hyaline, at times smoky. Abdomen globose to somewhat cylindrical, especially in male; yellow, darkish or reddish in ground color, usually with median black stripe on basal segments and tessellated pattern laterally... Zelia Robineau-Desvoidy

– Wing completely darkened. Abdomen black or dark brown; tergites 3, or 3 and 4, of some species each with pair of conspicuous rounded, silvery or bluish spots........................................................... Scotiptera Macquart

The monotypic South American genera Neozelia and Ophirodexia, which were not treated in the Central American key of Wood & Zumbado (2010), and Dolichozelia, described later and also outside of the range of that key, would key to couplet 177 in Wood & Zumbado (2010). The key in Santis (2022) should be used to differentiate these three genera. To further characterize the newly defined boundary of Zelia, the following generic characterization is given.

Body length of 9.5 mm – 12.8mm with a mean of 11.5mm. Compound eye usually bare, but with setulae in Z. pulchra . Frontal vitta and ocellar triangle usually dark brown. Fronto-orbital plate with silver pruinosity, in some species with dorsal region yellowish. Minute proclinate setae on fronto-orbital plate. Parafacial bare. Ocellar setae proclinate and well differentiated from the adjacent setae; postocellar setae proclinate. Inner and outer vertical setae subparallel to convergent. Postocellar setae proclinate. Width of parafacial measured between inner margin of compound eye and antennal insertion 0.3–1.5x the width of gena. Facial carina usually absent, present only in Z. obscura . Genal dilation with pale to brownish pruinosity and covered with black setulae. Facial ridge with small setulae near vibrissal insertion. Antennal base inserted below middle of compound eye. Arista densely plumose. Postpedicel 2–4x the combined length of scape and pedicel. Strong and convergent vibrissae; four to seven developed subvibrissal setae. Palpus cylindrical in males and clavate in females. Thorax brown to dark brown with silver or light golden pruinosity. Prescutum with four dark vittae, the two inner vittae thinner than the outer vittae. Notopleuron with two equal-sized setae. Two proepimeral setae. Two proepisternal setae. Two or three katepisternal setae. Postalar callus with two large and one smaller seta. Anepimeron with a single long seta. Propleuron and prosternum bare. Anatergite bare. Katepimeron with setulae anteriorly. Posterior spiracle with posterior lappet larger than anterior. Wing hyaline to smoky. Costal spine absent. Cell r 4+5 open at wing margin; length of opening shorter than crossvein r-m. Crossvein dm-cu sinuous. Base of vein R and apical third of R 4+5 dorsally and ventrally setulose. Vein M₁ ending at wing margin close to tip, bent forward to R 4+5, forming an angle slightly less than 90°, and convex after bend. Legs with claws straight with the tip curved. Abdomen conical, from basally large, rounded and tapering to tip to ovate and broad, sometimes with a small conical prolongation on tip of tergite 5; abdomen with silver pruinosity usually on anterior half, while entirely covered with silver pruinosity only in Z. wildermuthii . Mid-dorsal depression on syntergite 1+2 reaching the posterior margin. Tergite 3 without or usually with one pair of median marginal setae. Tergites 3 and 4 without discal setae, or with one erect pair, or with 2–4 pairs decreasing in size anteriorly. Tergite 4 with one row of median marginal setae and about 10–12 discal setae decreasing in size anteriorly. Tergite 5 with one row each of marginal and discal setae. Sternites hidden.

Male terminalia. Sternite 5 with well-developed lobules, setulose. Tergite 6 undivided. Sternite 6 asymmetrical. Syntergosternite 7+8 broad. Cerci separated and pointed, larger basally. Surstylus broad, and usually rounded at tip. Hypandrial arm short, hypandrial apodeme clearly distinguishable, with narrow central plate. Bacilliform sclerite rod-like. Pregonite and postgonite fused as curved elongate structure, without a distinct separation; pregonite connected basally to the hypandrium by a membrane (sometimes thin, almost sclerotized). Epiphallus present, fused with basiphallus. Basiphallus subretangular. Distiphallus with hinged connection between with distiphallus; distiphallus with extension of dorsal sclerite varying in size; dorsal sclerite ventrally serrulated; granular zone present, varying in size.

Female terminalia. Tergites 6 and 7 complete dorsally. Tergite 8 absent. Sternites 6 and 7 complete ventrally, with few setae in all posterior margin. Sternite 8 subrectangular with setulae mainly on the posterior margin. Sternite 9 as a reduced structure. Sternite 10 as a narrow strip. Cerci well developed, sub-circular, with several setae apically. Syntergite 9+10 absent

First instar larva. First segment with an elongate antenna, recurved clavate cephalic sensorium well developed. Cephaloskeleton thin and lightly sclerotized, with somewhat rounded mouth hook; intermediate region indistinct; dorsal and ventral cornua slightly diverging from each other; accessory sclerite posteriorly broad, narrowing anteriorly, anterior to mouth hook; sclerite of salivary gland as strip. Body covered with platelets with spines posteriorly; dorsal region with elongate subrectangular platelets with a single and strong spine, lateral and ventral region with transverse-oval platelets with 4–6 weak spines. Segments 11–12 with only anterior row of transverse-oval platelets with 4–6 weak spines. Posterior spiracles on small posterior protuberances, with long dorsal stylets in some species on segment 12.

Remarks. The concept of Zelia is broadened to include five new generic synonymies, in addition to the six already established before this contribution. There are two complexes of genera that closely resemble one another and will be discussed: 1) Zelia and Dolichozelia; and 2) Neozelia and Ophirodexia . The latter group presents two remarkable characters that could be synapomorphies: ocellar setae weak and male with pulvilli and claws short, shorter than fifth tarsomere. The other group of Zelia and Dolichozelia are characterized by strong ocellar setae, parafacial (measured between inner margin of compound eye and antennal insertion) 0.75X the width of gena, male with pulvilli and claws longer than fifth tarsomere, and male terminalia with pregonite fused to postgonite, but with a visible seam. Potential synapomorphies for Zelia are: parafacial 0.3–1.5x the width of gena, and abdomen somewhat ovate. However, these are widespread characters that can be found in a number of other Dexiini from the Neotropics; e.g., Ptilodexia Brauer & Bergenstamm, 1889 . Surely, the best indication of potential synapomorphies for Zelia species comes from the first-instar larva. Although not known from all species (in addition to the allied genera Dolichozelia, Neozelia and Ophirodexia), the remarkable characters of the larva are a good indication of a possible monophyletic Zelia . These are as follows: body covered with platelets with spines posteriorly; dorsal region with elongate subrectangular platelets with a single and strong spine, lateral and ventral region with transverse-oval platelets with 4–6 weak spines. Segments 11–12 with only anterior row of transverse-oval platelets with 4–6 weak spines. Posterior spiracles on small posterior protuberances.

Diversity and distribution. The 27 species currently assigned to Zelia are restricted to the New World and range from Canada to Argentina.