Allorrhina nigerrima ( Burmeister, 1842 )

Ratcliffe, Brett C., 2015, A Revision of the Neotropical Genus Allorrhina Burmeister, 1842 (Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini), The Coleopterists Bulletin 69 (1), pp. 91-113 : 91-113

Allorrhina nigerrima ( Burmeister, 1842)

( Figs. 25–29 )

Cotinis nigerrima Burmeister 1842: 259 (original combination).

Holotype female at MNHN, labeled “Type/Col. Dupont//Type”, examined. Type locality: “ Cayenne ”.

Gymnetis lugubris Thomson 1878: 13 .

Holotype female at MNHN, labeled “ lugubris Thoms. / Type T.C. 13/Cay//Th. Type//Ex Musaeo James Thomson//Type// Allorrhina nigerrima Burm. / female symbol/ G. Ruter det. 1965”, examined. Type locality: “ Cayenne ”. NEW SYNONYMY.

Description. Length 21.8–25.5 mm; width across humeri 12.1–15.0 mm. Clypeus, elytral suture, legs, and venter dark reddish brown to more commonly piceous, shiny. Frons, pronotum, elytra, and pygidium opaque, dark reddish brown to nearly black, lacking cretaceous marks. Setae of venter and legs in both sexes tawny and black mixed. Head: Clypeus of males deeply concave, with moderately large punctures moderate in density, setigerous; setae long, dense, tawny; lateral margins elevated, curving slightly mesad near apices, keel-like; clypeal apex with horn short, stout, subtriangular or subquadrate, projecting forward and obliquely upwards, apex not emarginate; occipital horn dorso-ventrally flattened, short, broadly arcuate, barely reaching middle of clypeus ( Fig. 26 ); frons with moderately long, tawny setae either side of middle in pristine specimens. Clypeus of females weakly concave, densely punctate to rugopunctate, punctures large, with short setae; apex broadly parabolic, strongly reflexed into low, rounded lobe at center; frons with broadly rounded, longitudinal tumescence at center extending past middle of clypeus ( Fig. 27 ), apex barely free. Interocular width equals 4.5–6.5 transverse eye diameters. Antenna with 10 antennomeres, club distinctly longer than antennomeres 2–7 in both sexes. Pronotum: Surface opaque, with small, sparse punctures near lateral margins. Lateral margins not emarginate between middle and basal angle, with complete marginal bead. Elytra: Surface opaque, usually lacking distinctly elevated, parallel costae on disc (costae occasionally weakly evident), suture slightly elevated on apical half. Surface with small, sparse punctures only near apices, apices at suture produced in males, subquadrate to slightly produced in females. Pygidium: Males with densely transverse, concentric, vermiform strigulae with minute, tawny setae; females similar but setae black, slightly longer. In lateral view, surface nearly flat to weakly convex in both sexes. Venter: Metasternum punctate on lateral thirds, punctures moderate in size and density, denser and larger on anterior and posterior margins; central third nearly impunctate. Mesometasternal process, in lateral view, moderately long, parallel to ventral axis of body; in ventral view, sides parallel, apex broadly rounded. Abdominal ventrites 1–6 of males with punctures moderate in size and density on lateral thirds, nearly impunctate on central third; females with punctures slightly larger, denser, completely covering sternite 6. Legs: Protibia of males slender, unidentate or bidentate near apex, occasionally with slight swelling behind middle suggestive of 3rd tooth, all but apical tooth usually obsolete. Females with protibia broader, strongly tridentate, basal tooth slightly removed. Parameres: In caudal view, form short, apices broadly separated, acute curving inwards towards one another ( Figs. 28–29 ). Basal piece slightly shorter than 1.5 times length of parameres.

Distribution. Allorrhina nigerima is known from the Guianas in northwestern South America and Amazonian Brazil. There are dubious records from Bolivia (1 with no data) at ZMHU, Peru (2 with no data) at ZMHU, Peru (1 from Satipo) at ZSMC, and Colombia (1 from Santa Fé de Bogotá) at FMNH.

Locality Records. 79 specimens from AMIC, BMNH, DEIC, FLSC, FMNH, IRSNB, MCZC, MHNG, MNHN, RMNH, ZMHU, and ZSMC. BRAZIL (10). AMAZONAS (8): Manaus, São Paulo de Olivença, Tapajos. PARÁ (2): Obidos. FRENCH GUIANA (58). CAYENNE (6): Cayenne, Kourou (Wayabo), Macouria (Matiti). SAINT-LAURENT-DU-MARONI (47): Les Hattes, Nouveau Chantier, Saint-Jean-du-Maroni, Saint- Laurent-du-Maroni. NO DATA (5). GUYANA (3). POTARO-SIPARUNI (3): Iwokrama Research Station at Kurupukari. SURINAME (6). NO DATA. NO DATA (2).

Temporal Distribution. February (1), May (5), July (5), August (8), September (3).

Diagnosis. Allorrhina nigerrima is remarkably similar to A. soror , and both species are partly sympatric in their distribution. Both males and females of A. nigerrima can be distinguished by an occipital tumescence that is short and broadly arcuate ( Fig. 26 ), whereas the tumescence in A. soror is more elongate and tapering in males ( Fig. 36 ) and with subparallel sides and a narrowly rounded apex in females. The club of the antenna is distinctly longer than antennomeres 2–7 in females of A. nigerrima and only slightly longer or subequal in length to antennomeres 2–7 in females of A. soror . The lateral margin of the pronotum is not emarginate between the middle and basal angles, while it is slightly emarginate in A. soror . These are subtle differences and can best be seen and compared with authoritatively identified specimens. Lastly, the parameres of A. nigerrima are, in caudal view, short with broadly separated, acute apices that curve towards one another, whereas the apices of A. soror are broadly rounded and not widely separated (compare Figs. 28 and 37 ).

Nomenclature. My examination of the types of both C. nigerrima and G. lugubris at MNHN in Paris showed that they were conspecific except that G. lugubris was 5 mm shorter in body length than C. nigerrima . Schenkling (1921) in his catalog listed nigerrima in both Allorrhina and Cotinis ! In spite of Gaston Ruter’ s 1965 label indicating the type of G. lugubris equaled C. nigerrima , G. lugubris has never been placed in synonymy but was, instead, listed in catalogs (e.g., Blackwelder 1944; Krajcik 1998) as a species of Hoplopyga Thomson , probably because of its vague original description combined with the smaller size.

Natural History. Nothing is known of the life history of A. nigerrima .

Figures

Figs. 25–29. Allorrhina nigerrima. 25) Habitus; 26) Male, head, arrow indicates occipital horn; 27) Female, head, arrow indicates frontal tumescence; 28–29) Parameres.

Figs. 35–38. Allorrhina soror. 35) Habitus; 36) Male, head, arrow indicates occipital horn; 37–38) Parameres.