Rhiginia cinctiventris ( Stål, 1872 )

Forthman, Michael & Gil-Santana, Hélcio R., 2021, Two new species of Rhiginia Stål, 1859, with taxonomical notes on species in the “ cruciata-group ” of this genus and an updated key to the New World genera of Ectrichodiinae (Heteroptera, Reduviidae), Zootaxa 4952 (2), pp. 201-234 : 205-206

Rhiginia cinctiventris ( Stål, 1872)

( Figs. 10–33 )

Morphological remarks. Males of R. cinctiventris have a subquadrate head with a relatively flat frons above the eyes ( Figs. 12, 16 , 20 , 28, 30 ), which distinguishes it from males of most other species of the cruciata -group that have a more ovate or globular head shape and/or a distinctly convex frons in lateral view; only R. lourdesae sp. nov. shares a similar head shape. The clypeus is moderately elevated, the eyes are large and oval in lateral view, and the large ocelli are separate by a distance less than or slightly more than the diameter of an ocellus and occupy about three-fourths of the ocellar tubercle in lateral view ( Figs. 10, 12, 14, 16 , 18, 20 , 26, 28–30 ). The anterior pronotal lobe is about half the length of the posterior lobe ( Figs. 10, 14 , 18 , 26 ). Further structural features, which also distinguish male R. cinctiventris from R. lourdesae sp. nov., are provided in the diagnosis of the latter species. Females ( Figs. 22–24 ) have a more ovate or globular head shape, a convex frons in lateral view, smaller ocelli and eyes, a more protuberant ventrolateral postocular region, the anterior pronotal lobe approximately half the length of the posterior lobe, and the hemelytra reaching the middle of tergite VII. This species is known to have a high degree of color variation that has not been observed in other species of the cruciata -group (see discussion below for further details).

Discussion. Stål (1872) described Ectrichodia cinctiventris based on males and females from Texas, USA, and reported the total length of this species as 18–20 mm. The species was considered close to R. cruciata , but is distinguished by the larger body size, structure of some portions of the head, and coloration, such as the smaller dark markings on the sulci of the pronotum. Only the NHRS (“Mus. Holm.”) was recorded as the depository of the type specimens ( Stål 1872). In NHRS, there are currently eight syntypes of this species (Gunvi Lindberg, pers. comm.), four of which were photographed for this study ( Figs. 10–25 ). Soon after its description, Uhler (1875) argued that specimens of E. cinctiventris vary extraordinarily in size and color, as well as contributing new distribution data (New Mexico [ USA] and Mexico). Champion (1899) examined nine males of E. cinctiventris , including one syntype, and stated that it would perhaps be an extreme form of the very variable E. crudelis (= R. crudelis ), from which it would differ by having larger eyes that are more prominent in the male and the sides of the head a little more rapidly converging posteriorly in the males. The species remained in Ectrichodia Lepeletier & Serville, 1825 by Lethierry & Severin (1896), Banks (1910), and Fracker (1912), until the current combination, Rhiginia cinctiventris , was presented by Van Duzee (1916) and followed by subsequent authors (e.g., Van Duzee 1917; Wygodzinsky 1949; Froeschner 1988; Maldonado 1990; Dougherty 1995; Baena & Susín 2007). The aforementioned authors recorded USA and Mexico as the geographical distribution of R. cinctiventris , except Dougherty (1995) also included El Salvador, Honduras, Costa Rica, and Panama.

As for many other species in the cruciata -group, the description of this species is primarily based on color patterns. Stål’s (1872) description of R. cinctiventris did highlight color variation on the abdomen, and this has been observed in many specimens distributed throughout much of the US and Mexico. Populations in these areas are dark brown-black, except for the sanguineous dorsal surface of the head and neck, pronotum (except black fascia on the sulci), base of the corium, and connexival margin. The black markings of the pronotum may be more extensive, reduced to spots, or nearly absent (e.g., see Figs. 10, 14 , 18, 22 , 26 ). The abdominal sternites may have large medial or paramedial dark orange patches (may be absent) (e.g., see Figs. 11–12, 15–16 , 19–20, 23–24 , 27–28 ). The sanguineous coloration may also range from yellow-orange to brown.

In her dissertation, Dougherty (1980) also briefly described a second color variant of R. cinctiventris from the southwestern US, which much of the head and pronotum are dark brown-black ( Figs. 32–33 ). While Dougherty’s (1980) description of this variant was never formally published in peer-reviewed journals, many North American entomologists have continued to treat these populations as a color variant of R. cinctiventris . Despite the very distinctive color differences, there are not many obvious morphological differences between southwestern US populations and the more geographically distributed color variant that closely matches Stål’s (1872) original description; specimens matching Stål’s (1872) description have the ocelli separated by a distance subequal to the diameter of an ocellus (about half the width of an ocellus in southwestern US populations described by Dougherty [1980]) and the anterior margin of the pronotum is distinctly concaved medially (straight to slightly concaved in southwestern US populations) ( Figs. 10, 14 , 18, 22 , 26, 29, 32 ). Given the lack of many more obvious structural differences, we refrain from treating the southwestern US populations as a distinct species and recognize that molecular data will be particularly useful to confirm hypotheses on the species limits of R. cinctiventris .

Sexual dimorphism in the shape of the head was documented by Stål (1872) in male and female syntypes collected from Texas, USA. According to Stål (1872), females also have a less distinct medial longitudinal sulcus on the pronotum, however, based on the type images, this may be subtle. Thus, this species appears to exhibit relatively limited sexual dimorphism ( Figs. 10–25 ).

Biology. This species has been reported to feed on millipedes ( Diplopoda) in the orders Spirobolida and Polydesmida in Costa Rica ( Forthman & Weirauch 2012), which is the first published instance of millipede feeding in Rhiginia .

Material examined. Type material: Texas // Belfrage // Ectrichodia / cinctiventris / Stål // Typus // NHRS-GULI / 000000172 (1 ♂) ( NHRS). Texas // Belfrage // Allotypus // NHRS-GULI / 000008172 (1 ♀) ( NHRS). Texas // Belfrage. // Paratypus // NHRS-GULI / 000008173 (1 ♂) ( NHRS). Texas // Belfrage. // Paratypus // NHRS-GULI / 000008174 (1 ♂) ( NHRS). Other specimen material: USA: AZ: Cochise Co., San / Bernardino NWR, central flat / areas; 31.341 -109.272, / 1150 m, - 19-20. VII.2020 / EE & KA Williams, lantern // Rhiginia cinctiventris / ( Stål, 1872) / det. M. Forthman 2020 (1 ♂) ( CSCA). USA: AZ: Cochise Co., / Leslie Canyon NWR Trail / 31.588 -109.513, 1415 m / 20-21. VII.2020 / EE & KA Williams, lantern // Rhiginia cinctiventris / ( Stål, 1872) / det. M. Forthman 2020 (1 ♂) ( CSCA). MEXICO: Durango / Rodeo VII- 22-1982 / Fred G. Andrews / blacklight // Rhiginia cinctiventris / ( Stål, 1872) / det. M. Forthman 2020 (1 ♂) ( CSCA).

Figures

FIGURES 10–17. Ectrichodia cinctiventris Stål, 1872, male syntypes deposited in NHRS. 10–13, catalog number NHRS- GULI000000172; 10, dorsal view, scale bar 10 mm; 11, ventral view; 12, lateral view; 13, labels; 14–17, catalog number NHRS-GULI000008173; 14, dorsal view, scale bar 10 mm; 15, ventral view; 16, lateral view; 17, labels. Made available by the Swedish Museum of Natural History under Creative Commons Attribution 4.0 International Public License, CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/legalcode.

FIGURES 18–25. Ectrichodia cinctiventris Stål, 1872, syntypes deposited in NHRS. 18–21, male, catalog number NHRS- GULI000008174; 18, dorsal view, scale bar 5 mm; 19, ventral view; 20, lateral view; 21, labels; 22–25, female, catalog number NHRS-GULI000008172; 22, dorsal view, scale bar 10 mm; 23, ventral view; 24, lateral view; 25, labels. Made available by the Swedish Museum of Natural History under Creative Commons Attribution 4.0 International Public License, CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/legalcode.

FIGURES 26–33. Rhiginia cinctiventris (Stål, 1872), non-type male specimens. 26–31, specimen from Mexico; 26–28, scale bar 2 mm; 26, dorsal view; 27, ventral view; 28, lateral view; 29 & 30, head, scale bar 1 mm; 29, dorsal view; 30, lateral view; 31, head, thorax and base of abdomen, ventral view, scale bar 2 mm; 32 & 33, specimen from Arizona (USA), scale bar 2 mm; 32, dorsal view; 33, ventral view.