Arvelius Spinola

Included Species:
    acutispinus Breddin
    albopunctatus (DeGeer)
        gladiator (Fabricius)
        leucostictos (Gmelin)
        luteicornis (Westwood)
    caballeroi Brailovsky
    confussus Brailovsky
    crassispinus Breddin [probably = albopunctatus (Perez-Gelabert & Thomas, 2005)]
    diluticornis Breddin
    ecuatorensis Brailovsky
    haitianus Brailovsky
    intermedius Brailovsky
    latus Breddin
    longirostris Brailovsky
    mormideoides Walker [nomen dubium]
    nigroantenatus Brailovsky
    paralongirostris Brailovsky
    peruanus Brailovsky [probably = porrectispinus (Rolston, unpublished notes)]
    porrectispinus Breddin
    tecpanus Brailovsky [probably = albopunctatus (Rolston, unpublished notes)]
    tuxtlaensis Brailovsky

Comments: This genus was recently revised (Brailovsky, 1981). He described a number of new species, several of which may prove to be junior synonyms of other species. For example, L. H. Rolston (in unpublished notes) has indicated that A. peruanus may be a synonym of A. porrectispinus, and A. tecpanus may be a synonym of A. albopunctatus. Also, Perez-Gelabert and Thomas (2005) speculated that A. crassispinus may also be a synonym of A. albopunctatus.

Arvelius can be separated into two species groups based on the male genitalia. The albopunctatus group has the head of the paramere distinctly bifid, splitting into two finger-like lobes that are obtusely rounded apically. They also have the lateral margins of the genital cup distinctly sinuous, with a prominent medial lobe. Members of this group include albopunctatus, caballeroi, crassispinus, diluticornis, paralongirostris, and tecpanus. As mentioned above, crassispinus and tecpanus may = albopunctatus. Nearly all, if not all, specimens I have examined have been A. albopunctatus. There is some variability in the shape of the parameres, especially in the relative width of the two lobes. I can usually separate specimens from the northern and southern hemispheres, suggesting that there may be more than one species, but there does appear to be intermediates, so I believe they are all one species. Also, Brailovsky (1981) placed some importance on the size and shape of the humeral angles, and the length of the rostrum. Perhaps I have not examined the proper specimens, but it appears that these two characters are quite variable, and I have some concerns about separating species based on either character.

The other species group, the porrectispinus group, has the head of the paramere more elongate and finger-like, usually oriented at an inclined angle, but definitely not distinctly bifid apically. Also, the lateral margins of the genital cup are not nearly so sinuous, lacking the large medial lobes. This group includes the following species: acutispinus, confussus, ecuatorensis, haitianus, intermedius, latus, longirostris, mormideoides, nigroantenatus, peruanus, porrectispinus, and tuxtlaensis. Again, Brailovsky used the size and shape of the humeral angles, and the length of the rostrum to separate many of these species. Rolston (unpublished notes) has indicated that peruanus may = porrectispinus. At present, I am only able to identify with confidence two of the above species. A. porrectispinus is a fairly widespread, relatively common species that has a small, obtuse, medial prominence along the external margin of the paramere head. A. intermedius is a closely related species occurring in southern South America. In A. intermedius, this small protuberance is much larger and elongate, almost forming a digitoid projection.

Breddin, G. 1909. Beiträge zur Systematik der Pentatomiden Südamerikas. Drittes Stück. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1909:154-161.

Brailovsky, H. 1981. Revisión del género Arvelius Spinola (Hemiptera-Heteroptera-Pentatomidae-Pentatomini). Anales del Instituto de Biología Universidad Nacional Autónoma de México (Zool.) 51(1)[1980]:239-298.

Key to male specimens of species of Arvelius Spinola
(translated and modified from Brailovsky, 1981)

1 Lateral margins of genital cup opening each provided with a lateral lobe, which delimits two concavities; each paramere in form of an "F"	2
- Lateral margins of genital cup opening lacking lateral lobes; each paramere in form of bird wing	7

2(1) Tylus, when viewed from above, partially covered by juga [Lesser Antilles]	crassispinus Breddin
- Tylus of uniform width, not covered by juga	3

3(2) Humeral spines of pronotum long, thin	4
– Humeral spines of pronotum short, robust or thin	5

4(3) External surface of second and basal half of third antennal segments provided with a solid, continuous, dark reddish or brown line; each paramere with a conspicuous elevation on the external margin of its body [Mexico]	tecpanus Brailovsky
– External surface of second and basal half of third antennal segments lacking solid, continuous, dark reddish or brown line; each paramere lacking conspicuous elevation on external margin of its body [widespread: Texas to Argentina, West Indies]	albopunctatus (DeGeer)

5(3) Total length 11.5-12.5mm (13.5 in females); humeral spines of pronotum extraordinarily short and robust [Puerto Rico]	caballeroi Brailovsky
– Total length 12.2-14.2mm (14.8-15.6 in females); humeral spines of pronotum short and robust	6

6(5) Rostrum reaching the anterior margin of the seventh abdominal sternite [Brazil]	paralongirostris Brailovsky
– Rostrum not reaching beyond the fourth abdominal sternite [Argentina, Bolivia, Brazil, Paraguay, Uruguay, Venezuela]	diluticornis Breddin

7(1) Margins between juga and tylus pale orange or yellow	8
– Margins between juga and tylus dark brown	12

8(7) Rostrum reaching to seventh abdominal sternite [Brazil, Guyana]	longirostris Brailovsky
– Rostrum not extending beyond the sixth abdominal sternite	9

9(8) Anterolateral margins of pronotum concave, curved; humeral spines of pronotum very elongate	10
– Anterolateral margins of pronotum straight; humeral spines of pronotum moderately large	11

10(9) Humeral spines of pronotum large and robust; ventral margin of pygophore four-lobed; superior margin of each paramere with a notable, medial, blunt prominence, inferior margin straight [Brazil, Colombia]	confussus Brailovsky
– Humeral spines of pronotum large and acuminate; ventral margin of pygophore not four-lobed; superior margin of each paramere with medial prominence slightly elevated, and inferior margin with a small lobe [Mexico to Brazil and Surinam, West Indies]	porrectispinus Breddin

11(9) Apex of scutellum acute; each paramere without prominent basal protuberance [Haiti]	haitianus Brailovsky
– Apex of scutellum blunt; each paramere with a prominent basal protuberance [Colombia, Peru]	peruanus Brailovsky

12(7) Tylus, when viewed from above, covered in part by juga [Brazil]	latus Breddin
– Tylus uniformly wide	13

13(12) Rostrum reaching the seventh abdominal sternite; second, third, and fourth antennal segments uniformly colored intense dark brown (fifth antennal segment faltante); internal surface of each femur provided with a dark brown stripe on distal third [Peru]	nigroantenatus Brailovsky
– Rostrum not exceeding the sixth abdominal sternite; second, third, fourth, and fifth antennal segments pale yellow with dark reddish-brown punctures; each femur uniformly straw-yellow	14

14(13) Rostrum reaching sixth abdominal sternite; humeral spines of pronotum moderately large and robust [Argentina, Brazil]	intermedius Brailovsky
– Rostrum not surpassing the fifth abdominal sternite; humeral spines of pronotum large and thin	15

15(14) Second, third, fourth, and fifth antennal segments uniformly straw yellow; rostrum reaching the fourth abdominal sternite [Mexico]	tuxtlaensis Brailovsky
– Second and basal half of third antennal segments with dark brown border on external surface, and apical half of antennal segments three, four, and five dark red or brown; rostrum reaching fifth abdominal segment	16

16(15) Humeral spines of pronotum extraordinarily large and thin; rostrum extending to the fourth abdominal sternite; basal protuberance of each paramere triangular [Bolivia, Brazil, Colombia, Paraguay, Peru, Venezuela]	acutispinus Breddin
– Humeral spines of pronotum moderately large and thin; rostrum reaching the fifth abdominal sternite; basal protuberance of each paramere bilobed [Ecuador]	ecuatorensis Brailovsky

David A. Rider
Professor of Entomology
North Dakota State University
E-Mail: David.Rider@ndsu.edu