Zelus grassans Stal , 1862

Zhang, Guanyang, Hart, Elwood R & Weirauch, Christiane, 2016, A taxonomic monograph of the assassin bug genus Zelus Fabricius (Hemiptera: Reduviidae): 71 species based on 10,000 specimens, Biodiversity Data Journal 4, pp. 8150-8150 : 8150

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Zelus grassans Stal , 1862


Zelus grassans Stal, 1862 View in CoL

Zelus grassans Stål, 1862, p, 450, orig. descr.; Stål, 1872, p. 91, cat.; Lethierry and Severin, 1896, p. 152, cat.; Champion, 1898, p. 256-257, Tab. XV, fig. 16, 17, note and fig.; Kuhlgatz, 1902, p. 266, note; Fracker, 1913, p. 239, 240, key and list (subgenus Diplodus ); Wygodzinsky, 1949a, p. 49, checklist; Hart, 1986, p. 546-547, redescription, note, fig. and key; Maldonado, 1990, p. 327, cat.

Diplodus grassans : Walker, 1872, p. 124, cat.; Uhler, 1886, p. 24, checklist.


Type status: Holotype. Occurrence: catalogNumber: UCR_ENT 00075073 ; occurrenceRemarks: Verbatim label info: Mexico coll. Signoret / grassans det. Stal / B.C.A. Rhyn.II. Zelusgrassans St. / Zelusgrassans Stal / Holotype / Lectotypus Zelusgrassans STAL, 1862 etik. Hecher 1996 REDV. 471/1; recordedBy: Signoret; sex: Adult Female; Taxon: scientificName: Zelusgrassans; family: Reduviidae; genus: Zelus; scientificNameAuthorship: Stål, 1862; Location: country: MEXICO; Identification: identifiedBy: G. Zhang; dateIdentified: 2013; Record Level: institutionCode: NHMW


Figs 91, 92, 93

Male: (Fig. 91a, b, c) Medium-sized, total length 12.42-15.02 mm (mean 13.76 mm, Suppl. material 2); slender. COLORATION: Orangish to reddish, with variable amount of black areas. Legs reddish-brown, pro-femur with broad dark bands; meso and meta-femora reddish-brown, apex dark, two narrow indistinct dark bands medially. Black, red or whitish markings on abdominal venter. VESTITURE: Sparsely setose. Head with short, spine-like setae dorsally, finer, short to long semi-erect and erect setae over entire surface. Anterior pronotal lobe with sparse, erect setae on entire surface; posterior lobe with short, heavy, erect setae on dorsal surface, longer laterally. Abdomen with short to moderately long erect setae on entire surface. STRUCTURE: Head: Cylindrical, L/W = 2.22. Postocular lobe short; in dorsal view distinctly narrowing through anterior 1/2, posterior 1/2 constant, tube-like. Eye prominent; lateral margin much wider than postocular lobe; dorsal margin attaining postocular transverse groove, ventral margin removed from ventral surface of head. Labium: I: II: III = 1: 1.5: 0.4. Basiflagellomere diameter larger than that of pedicel. Thorax: Anterolateral angle rounded; medial longitudinal sulcus evident throughout, deepening posteriorly. Posterior pronotal lobe with rugulose surface; disc distinctly elevated above humeral angle; humeral angle rounded or with minute projection. Scutellum short; apex angulate. Legs: Relatively robust, mesofemoral diameter greatest. Hemelytron: Surpassing apex of abdomen by more than length of abdominal segment seven; quadrate cell moderately sized; Cu and M of cubital cell converging. GENITALIA: (Fig. 92) Pygophore: Ovoid; not expanded laterally in dorsal view. Medial process cylindrical; slender; long, only slightly shorter than paramere; laterally somewhat compressed; posteriorly directed; curved at middle; apex in posterior view acute, without modification; base humped in lateral view. Paramere: Sickle-shaped; long, not reaching apex of medial process; directed toward medial process; strongly curved ventrad at mid-point, apex recurved dorsally; apical portion tapered. Phallus: Dorsal phallothecal sclerite somewhat pandurate, fiddle-shaped, medially constricted; apical portion of phallothecal sclerite gradually tapering, flat, laterally rounded, not forming angle; apex abruptly truncate, not emarginate; posterior margin of foramen nearly straight. Struts attached to dorsal phallothecal sclerite; apically separate, connected by bridge; basally separate. Basal plate arm moderately robust; basally slightly touching, not clearly fused; in lateral view very slightly curved; bridge extremely short; extension of basal plate expanded onto arm.

Female: (Fig. 91d) Similar to male, except for the following. Larger than male, total length 14.06-18.13 mm (mean 16.91 mm, Suppl. material 2). Reduced amount of dark areas on body, dorsal surface usually yellowish.


Can be distinguished by the following combination of characters: Humeral angle without or with minute processes; head and legs predominantly reddish; abdominal segments usually banded; pronotum with erect, nearly spine-like setae. Males can also be recognized by the paramere greatly curved at middle and distinctly tapered apically; the medial process curved and directed posteriad; and the dorsal phallothecal sclerite constricted and the apex truncate, without emargination. The only species within the range of Z. grassans with which the females may be confused is Z. ruficeps . The pronotal armature readily separate them, that of Z. ruficeps consisting of broad dentate lateral processes while those of Z. grassans are as given above.


From Mexico to Panama (Fig. 93). Countries with specimen records: Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua and Panama.

Taxon discussion

There is a great amount of size and color variations in Z. grassans . The dorsal coloration varies from almost entirely yellowish with only a narrow transverse dark band near the posterior margins of the pronotal lobes, to almost entirely dark brown. The legs show a similar range of coloration, from almost entirely light to entirely dark. The contrasting black and orange or red colors and the banded abdomen in many specimens of Z. grassans suggest that they may be mimics of Dysdercus , whose members have similarly strongly contrasting red and black colors. They have been observed to co-occur on the same plant (Zhang, unpublished), indicating that this may be a case of aggressive mimicry.