Pachystethus viduus Newman 1838
Creators: name: Ramírez-Ponce, Andrés
name: Morón, Miguel Angel
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Rutelidae
Pachystethus
Pachystethus viduus

description: Pachystethus viduus (Newman, 1838)
(Figs. 2–7, 42 a–d, 48a, b)
Popillia sticticollis Newman, 1838: 337 (synonym)
Popillia semirufa Newman, 1838: 338 (synonym)
Type specimens. Popillia vidua Newman, 1838: 337. Not examined, depository unknown. Type locality: “ Mexico ”. Popillia sticticollis Newman, 1838: 337. Female lectotype examined, deposited in NHM. Popillia semirufa Newman, 1838: 338. Not examined, depository unknown.
Type material revised. Lectotype (1 female: NHM), labeled: a) “ Popillia sticticollis, newm. type mexico” (handwritten), b) “Ent. Club. 44-12.” (typeface), c) “mexico 44´12” (handwritten), d) (female symbol, typeface), e) “ Type ” (typeface), f) “ Popillia Sticticolli, N ”… (could not be deciphered; handwritten), f) “ Pachystethus viduus LECTOTYPE female Ramírez-Ponce y Morón det. 2011”. Lectotype here designated. Statement of taxonomic purpose: A lectotype is designated for P. sticticollis Newman in order to preserve the nomenclatural stability by selecting this as the sole type name-bearing specimen of this taxon. Additional material examined (6 males, 6 females; CNIN, IEXA, MXAL, NHM, ZMHB) labeled: Veracruz, Río Jamapa, 6-XI-75, col. diurna, Figueroa (handwritten) (1 male, CNIN); Janapa, Veracruz 6-XI-75, Col. Brailovsky (handwritten), (1 male and 1 female, CNIN; 1 female, NHM); Río Jamapa Ver 12-VIII-74 (handwritten), (1 male and 1 female, CNIN; 1 female, NHM; 1 female, IEXA); same data except 13-VIII-74 (handwritten) (1 male, CNIN); same data except 6-IX-75, Brailovsky (handwritten) (1 male and 1 female, MXAL); all specimens labeled: Pachystethus viduus (Newman) Ramírez-Ponce y Morón det. 2011 (typeface). a) “ Mexico ” (handwritten), b) “Hist.-Coll. (Coleoptera) Nr. 24497 Anomala vidua Newm. Mexico, Chevr. Zool. Mus. Berlin” (typeface), c) “Coll. Thieme” (typeface) (1 male, ZMHB).
Redescription. Lectotype. Female. Length 12.0 mm, width 6.3 mm. Color bright reddish yellow on most of body surface, except, shiny black on antennal club, elytral suture, lateral borders of elytra, lateral borders of scutellum, sternum, apex of tibiae and tarsi. Pronotum with one dark spot at each side. Elytra flattened, ovate and elongate, nearly smooth, striae weakly impressed with disperse and shallow small punctures; elytral costae weakly defined, mainly near apical calli; elytral suture raised on posterior half; brief preapical slop. Metasternum with a large red spot at middle, surrounding black meso-metasternal process. Antennal club as long as the length of funicle. Body larger than in male; epipleural fold swollen and enlarged; protibiae and protarsi narrower than in male, protarsomeres 1–4 as long as in male. Genital plates of medium size, elongate, subtriangular, with widely rounded apex (Fig. 7).
Redescription. Male. Length 11.0 mm, width 5.0 mm. Color shiny black on nearly complete body; reddish dark brown on pedicel and funicle. Head. Clypeus subtrapezoidal; anterior border curved, briefly raised, and not directed forward; anterior angles widely rounded; clypeal surface with irregular, weakly rugose, shallow punctures. Frontoclypeal suture briefly sinuate at each side. Frons slightly convex, glabrous, sparsely punctate; punctures irregular, shallow, rounded on the center, more disperse on lateral and posterior margins. Punctures around eyes scattered. Antennal club slightly longer than the length of all preceding antennomeres combined; lamellar shape semiovate, straight (Fig. 3). Eyes medium size, ovate; ocular margin dorsally noticeable and setose. Eye canthus thick; with glabrous, rounded apex and flattened surface with scarce shallow punctures. Maxillary basistipe convex, with irregular punctation; labrum wide and sinuate; labium sinuate, as long as wide, with irregularly rugopunctate, setose prementum. Pronotum wider than long, moderately convex; surface with scattered, minute, round punctures; lateral borders angled with bulky sides and deep lateral pits; posterior angles raised. Mesoepimera not exposed over humeral calli. Space between mesocoxae wide, meso-metasternal process long and stout, briefly projecting anteriorly past mesocoxa with wide, rounded apex directed downward; metasternum densely covered with wide punctures, sides densely setiferous, mesial region glabrous with weak longitudinal sulcus. Elytra flattened and ovate, nearly smooth, striae weakly impressed with disperse and shallow small punctures; elytral costae weakly defined, mainly near apical calli; elytral suture raised on posterior half; brief preapical slope; lateral margins nearly straight, with scattered row of stout, short setae all along its length. Epipleural fold narrow, briefly swollen in lateral view, abruptly narrowed after metacoxa. Scutellum: slightly longer than wide; lateral margins angled; apex acute; surface with sparse, irregular punctures. Abdomen: sternites with scarce setae on a discontinuous central row of irregular, small punctures. Legs: protarsomeres 1–4 short and wide, wider than protarsomere 5 but equal in length. Protibia stout; lateral borders divergent towards apex; external border with proximal denticle short and rounded; distal denticle long, oblique (Fig. 2). Mesofemora with a well-defined longitudinal keel, with long setae. Metafemora without keel. Metatibia with two transverse keels and spine-like, short setae; apex of metatibia clearly swollen. Metatarsomere 1–2 longer than metatarsomere 3–5. Genitalia (Figs. 4–6): parameres simple, shorter than the length of tectum, with upper part smooth, apicies narrowed, briefly upturned and convergent; lower part of parameres briefly curved backwards. Basal half of tectum wider than distal half, with outstanding posterolateral calli. Basal piece with long and round pointed apodema. Spiculum gastrale (Fig. 6) narrow, basal part curved, shorter than lateral sclerites; associated plates large, subrounded, with numerous long setae near exterior border.
Variation (n = 12). Length: 9.5–12.0 mm, width: 4.0– 6.3 mm. Some specimens are completely shiny black, with reddish dark luster on protibial denticles, but others are reddish yellow on clypeus, anterior half of frons, scape, pedicel, funicle, lateral margins of pronotum, sterna, abdomen, pygidium, basal parts of mesofemora and metafemora and tibiae; dark red on protibiae; shiny black on antennal club, posterior half of frons, disc of pronotum, scutelum, elytra, and distal parts of mesofemora and metafemora, tibiae, and all tarsomeres. Width and extension of epipleural fold slightly variable.
Diagnosis. Clypeus subtrapezoidal. Pronotum with scattered minute (approximate diameter 0.020 mm), circular, shallow punctures. Elytral surface nearly smooth; striae weakly indicated by irregular rows of shallow minute punctures; lateral margins without bend. Protarsomeres 1–4 shortened, but slightly longer than protarsomere 5. Protibia considerably wider on distal third, lateral borders divergent towards apex. Parameres short and complex, with upper part narrowed, convergent and slightly curved towards apex (Table 1).
Etymology. Although not cited in the original description, probably derives from the typical black coloration in males, which is associated with the habit of a widow or widower wearing black (from Latin viduus: deprived of or lacking a husband, wife, etc.) (Glare 1968).
Distribution, phenology, and natural history. This species is distributed in the central coastal plain of State of Veracruz in Mexico at 10 m of elevation (Fig. 54). Adults are active during August to November. No plants have been recorded as hosts for adults, and the immature stages remain undescribed.
Remarks. In the original description of P. viduus (as well as in their synonyms P. sticticollis and P. semirufa), Newman (1838) indicated the coloration as the only criterion for the distinction between these species, without data on the number and sex of the specimens examined. This species, along with P. nectoctenus and P. crassesculptus, are the largest in the genus. Pachystethus viduus and P. nectoctenus are similar, but they are easily differentiated by the form of the parameres, shape of protibia and protarsus, and fine dorsal sculpture (Table 1).
description: Published as part of Ramírez-Ponce, Andrés & Morón, Miguel Angel, 2012, Revision of the genus Pachystethus Blanchard with description of three new species from Mexico (Coleoptera: Scarabaeidae: Rutelinae: Anomalini), pp. 1-24 in Zootaxa 3394 on pages 5-7, DOI: 10.5281/zenodo.210542