Eucelatoria rivalis
Creators: name: Burington, Zelia L.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Tachinidae
Eucelatoria
Eucelatoria rivalis

description: Eucelatoria rivalis (Reinhard, 1953)
(Figs 15, 60, 179)
Xiphomyia rivalis Reinhard, 1953: 101. Holotype, Mexico, Acatlipa (CNC).
Eucelatoria rivalis: Wood (1985: 44).
Type material examined. Holotype ♀, labeled “Acatlipa, mex./ VII[/]11[/]50/ Coll. WGDowne”, “ Holotype / Xiphomyia / rivalis/ Reinhard” (CNC).
Other material. 2 ♀♀. Costa Rica — Guanacaste: 1 ♀, “LEGS AWAY FOR DNA”, “DHJPAR0035639”, “Voucher: D.H. Janzen & W. Hallwachs / DB: http://janzen.sas.upen.edu/ Area de Conservacion Guanacaste,/ COSTA RICA./ 09 -SRNP- 13752”, “Janzen08”, “ZLB_E.Ferox 00010 (CNC). Mexico — Morelos: 1 ♀, “ Cuernavaca 12 Mi./ E., 4300′ Morelos / Mex. 14-VIII-1954 / J. G. Chillcott ” (CNC).
Recognition. This species is very close to E. sabroskyi sp. nov., as both have four relatively thin thoracic vittae, strong ocellar setae, broad parafacials, and long piercers; E. rivalis differs in that the yellow tomentum extends over the upper one-fourth to one-half of the parafacial, whereas the parafacial of E. sabroskyi sp. nov. is entirely gray.
Redescription. Female [redescribed from 3 specimens]. Length 7.0– 9.8 mm (mean = 8.0 mm).
Head. Fronto-orbital plate, vertex, upper half of post-ocular plate, and vibrissal angle tomentum yellow. Genal dilation, postgena, and occiput tomentum ash-gray. Parafacial yellow on upper one-fourth to one-half, merging to gray on lower portion. Pale occipital setulae gray to yellow gray. Ocellar setae usually strong, one-half to subequal to length posterior reclinate orbital seta. Gena with 3 setae, subvibrissal ridge with 1–2 setae. Facial ridge with setulae on ventral one-third or less. Postocellar setae one-half to subequal to length of ocellar setae. Paravertical seta one-half to three fourths length of postocellar setae. Outer vertical seta one-fourth to one-third length of inner vertical seta. Reclinate orbital setae 3. Frontal setae 5–6, last frontal seta level with base of postpedicel to base of arista. Eye apparently bare. Eye height to head height ratio 0.81–0.85 (mean = 0.84). Postpedicel length 0.37–0.39 (mean = 0.38) height of head. Facial ridge length 0.51–0.55 (mean = 0.52) height of head. Parafacial width 0.10–0.11 (mean = 0.11) lateral length of head. Pedicel 0.35–0.40 (mean = 0.38) length of postpedicel. Postpedicel width 1.30–2.70 (mean = 1.84) times width of parafacial in lateral view. Vertex 0.26–0.27 (mean = 0.26) width of head in dorsal view. Palpus yellow to tan at apex, dark brown at base; subcylindrical to slightly dilated at apex; with short, stout setulae dorsoapically and thinner, longer setulae laterally.
Thorax. Dorsomedial length 1.3–1.4 times width of thorax. Lateral tomentum ash-gray. Dorsal tomentum gray to yellow. Presutural outer vitta triangular, pointed anteriorly, distinctly to slightly disconnected from bar shaped vitta leading from anterior margin. Postsutural outer vitta fusiform, broader anteriorly, distinctly disconnected from presutural outer vitta and inner vittae. Inner thoracic vittae bar-shaped, width generally one-half width of outer vittae, extending to level of second postsutural acrostichal seta. Scutellar dorsal tomentum diffuse yellow to gray; covering entire area, denser at apex. Postpronotum with 3 setae. Presutural area with 2 setae, the anterior seta weak. Postsutural area with 3 setae. Scutellum with 1 pair discal setae. Fore tibia with 2–3 posterodorsal setae. Wing hyaline. Calypters tan to cream colored.
Abdomen. Cuticle and setulae entirely black. Dorsal tomentum bands gray covering one-half area of T3–5. Ventral tomentum bands gray, covering two-thirds to three-fourths area T3–5. T4 with 1 pair erect median marginal setae and 3–4 pairs of erect lateral marginal setae, the median and lateral setae forming a widely spaced continuous row.
Female terminalia (Fig. 60). Piercer generally extending past apex of T3, in one specimen to base of abdomen; in lateral view gradually curved to bent apex; in posterior view parallel sided on basal half, then gradually tapered to apex. Aculeate lobe at least three times height of segment 7 base. End tergite not visible. Cercus with 6–7 setulae; ventral elongation not visible. Postgenital plate with 10–12 setulae. [Left undissected due to small number of specimens.]
Host(s). One individual has been reared from Hahncappsia Munroe species (Crambidae) feeding on Melampodium divaricatum (Rich.) DC. (Asteraceae) (Janzen & Hallwachs 2008).
Geographic extent and seasonal occurrence. Individuals have been collected from tropical and subtropical dry forest in Mexico and Costa Rica, from sea level to 1300 m elevation (Fig. 179).
Discussion. The morphological difference between E. rivalis and E. sabroskyi sp. nov. is very small, and the specimens included here vary somewhat in the length of the piercer and coloration of the head. Genetically they are distinct (Fig. 1). The small number of specimens makes it impossible to know the true range of intraspecific variation within this group at this time.
description: Published as part of Burington, Zelia L., 2022, A taxonomic revision of the Eucelatoria ferox species group (Diptera: Tachinidae), pp. 1-104 in Zootaxa 5143 (1) on pages 37-38, DOI: 10.11646/zootaxa.5143.1.1, http://zenodo.org/record/6601404