Euschistus (Euschistus) tacitus Bianchi & Grazia

Bianchi, Filipe Michels, Barão, Kim Ribeiro & Grazia, Jocelia, 2017, Review of the sulcacitus group of Euschistus (Pentatomidae: Pentatominae: Carpocorini) with description of the internal female genitalia and a new species, Zootaxa 4362 (3), pp. 348-358: 356-357

publication ID

publication LSID

persistent identifier

treatment provided by


scientific name

Euschistus (Euschistus) tacitus Bianchi & Grazia

sp. nov.

Euschistus (Euschistus) tacitus Bianchi & Grazia  sp. nov.

( Figs 5View FIGURES 1–5, 18–20View FIGURES 6–20, 26View FIGURES 21–26, 39–41View FIGURES 27–41, 57–59View FIGURES 45–59, 64View FIGURES 60–64)

Etymology: Epithet alludes to the external morphological similarities among the species of the sulcacitus  group and the new species. From taceo (Latin), to be silent, say nothing; tacitus  , meaning implied, unmentioned, in reference to a hidden species.

Distribution: Mexico (Chiapas, Veracruz); Costa Rica (Alajuela).

Type locality: Lacanja , Chiapas, Mexico.

Type material: Holotype: MEXICO: ♂, Chiapas: Near Lacanjah, 310m, 16.77°N 91.13°W, 0 8 Jul 2009, D. Forero & G. Zhang [MEX09_SM_L15] / PTM00283View Materials ( UNAM).GoogleMaps  Paratypes: COSTA RICA: 1♂ 1♀ Alajuela: On hwy 4S of Mirador, 139m, 10.50°N 84.59°W, 0 9 Dec 2008, Weirauch & Forero [CR 0 8 L12] (1♂ UFRG) / PTM0285View Materials (1♀ UFRG) (abdomen removed)GoogleMaps  ; 1♂ Guanacaste: 16 km E of La Cruz, Hacienda Los Inocentes , 6.23.0 4, MV+UV light / COLLECTIO NACIONAL MUSEUM Praha, Czech Republic (1♂ NMPC)  ; 1♂ Dos Rios, 8.16.0 2 / COLLECTIO NACIONAL MUSEUM Praha, Czech Republic (1♂ NMPC)  ; 1♀ Puntarenas: Hacienda Baru near to Dominical, 2.16.0 4 MV + UV light / COLLECTIO NACIONAL MUSEUM Praha, Czech Republic (1♀ MNRJ)  ; MEXICO: 1♂, 2♀ Veracruz: Rd between Cuetzalapan and Miguel Hidalgo, 361m, 18.37°N 95.01°W, 0 5 Jul 2009, D. Forero & G. Zhang [ MEX09_SM_L5] / PTM00287View Materials (1♀ UFRG) (abdomen removed), PTM00288 (1♀ UFRG) (abdomen removed), PTM00289 (1♂ UCR)GoogleMaps  ; 1♂ Chiapas: Agua Fria, about 8.5 km off Hwy 186, 23m, 17.74°N 92.08°W, 0 6 Jul 2009, D. Forero & G. Zhang [ MEX09_SM_L7] / PTM00286View Materials (1♂ UFRG) (pygophore removed)GoogleMaps  ; 3♂ 2♀ Near Lacanjah, 310m, 16.77°N 91.13°W, 0 8 Jul 2009, D. Forero & G. Zhang [ MEX09_SM_L15] / PTM0284 (1♂ UFRG), (1♂ 1♀ AMNH, 1♂ MNRJ 1♀ UNAM)GoogleMaps  .

Description: Dorsal surface light brown; punctures black; punctures smaller on hemelytra than on remaining body parts. Humeri acutely projected laterally, but not developed as a spine, varying from light brown to reddish. Ventral surface greenish to light-yellow; punctures concolorous with the surface. Antennae uniformly yellow to orange ( Fig. 5View FIGURES 1–5).

Head longer than wide; head punctate, punctures less dense on disc. Clypeus rounded apically; clypeus slightly longer than mandibular plates, rarely equal in length. Mandibular plates rounded apically. Rostrum reaching metacoxae. Anterolateral margins of pronotum toothed anteriorly and smooth posteriorly; teeth-like projections small, dark brown. Scutellum reaching abdominal segment V; anterolateral angles foveate. Punctures on scutellum and hemelytra smaller apically than basally. Membrane of hemelytra light brown; exocorium reddish in some specimens. Evaporatorium of metasternal glands not surpassing median line between ostiole and lateral margin of mesopleuron; spout peritreme. Presence of 1+1 dark spots at base of leg between epimeron and episternum of each pleurite, plus 1+1 at metepimeron medially. Legs concolorous with ventral surface of thorax; small dark dots on femora and tibiae.

Abdomen: dorsally, disc of connexivum yellow, black stripes on anterior and posterior margins; ventrally, anterior angle with dark spot. Spiracles concolorous with abdominal sternites.

Male genitalia: Pygophore trapezoidal. Dorsal rim uniformly concave in dorsal view ( Fig. 18View FIGURES 6–20) median projection of dorsal rim long, sinuosity shallow; superior process of dorsal rim tooth-like. Ventral rim slightly sinuous, convex medially in ventral view ( Fig. 20View FIGURES 6–20). In posterior view, ventral rim protuberant medially; superior layer of ventral rim excavated in V-shape in posterior view ( Fig. 19View FIGURES 6–20). Paramere: margin connecting basal and apical process slightly concave; apical process somewhat spatulate at apex; middle process not developed ( Fig. 26View FIGURES 21–26).

Female genitalia: Posterior margin of gonocoxites VIII concave, posterolateral margin of gonocoxites VIII projected posteriorly, reaching middle of gonocoxites IX. Gonocoxites IX 2 times wider than long, lateral margins strongly rounded; anterior margins of gonocoxites IX straight, posterior margin convex ( Fig. 57View FIGURES 45–59). Posterior region of ductus receptaculi proximalis straight, not dilated. Ductus receptaculi distalis dilated adjacent to anterior annular flanges. Pars intermedialis sclerotized at basal three-fourths ( Fig. 64View FIGURES 60–64).

Comments. The external morphology of the sulcacitus  group is homogeneous among its species. Some characteristics (e.g. coloration of dorsal and ventral surfaces of body, shape and length of humeral angles, and total body length) vary intraspecifically, making them useless to species diagnosis. Otherwise, the genitalic morphology provides valuable characters to species definition. Euschistus tacitus  sp. nov. is more similar to E. sulcacitus  than to the others species of the group by the posterior margin of pygophore slightly sinuate, convex mesially; and by the laterotergites IX not surpassing dorsal band that unites laterotergites VIII in posteroventral view. Euschistus tacitus  sp. nov. can be distinguished from E. sulcacitus  by the inferior layer of ventral rim mesially tumescent in posterior view, and posterior margin of gonocoxites VIII mesially slightly concave.


Mexico, Mexico D.F., Universidad Nacional Autonoma de Mexico


Brazil, Rio Grande do Sul, Porto Alegre, Universidade Federal do Rio Grande do Sul, Instituto de Biologia


Czech Republic, Prague, National Museum (Natural History)


Brazil, Rio de Janeiro, Sao Cristovao, Universidade do Rio Janeiro, Museu Nacional


USA, California, Riverside, University of California


USA, New York, New York, American Museum of Natural History


Universidad Nacional Autonoma de Mexico


Instituto de Biologia


National Museum Prague


Museu Nacional/Universidade Federal de Rio de Janeiro


American Museum of Natural History