Microchilus lineatus Blanchard, 1851

Jameson, Mary Liz, 2008, Review of the genus Microchilus Blanchard (Coleoptera: Scarabaeidae: Rutelinae: Geniatini), Insecta Mundi 2008 (25), pp. 1-14 : 9-11

Microchilus lineatus Blanchard, 1851

( Fig. 1-2 , 8-13 , 15, 17, 19, 21-22 , 25)

Microchilus lineatus Blanchard 1851: 240 . Type specimens not examined. Probably at Paris. Blanchard’s description provided no indication regarding the number of specimens or gender of specimens used in the original description. The only locality information in the original description is “ Brésil ”.

Description. Length 6.1-7.9 mm; width at humeri 3.2-4.2 mm. COLOR: Head, pronotum, scutellum, pygidium, and venter red-brown to castaneous; elytra tan with well-defined or poorly defined longitudinal, castaneous vittae; elytra rarely entirely castaneous. HEAD: Frons in lateral view with base and disc flat or weakly convex, punctate; punctures small and moderate in size, moderately dense, some setose; setae minute, tawny. Interocular width of male 5.8-6.7 transverse eye diameters; female 8.1-10.9. Clypeus in lateral view with base and disc weakly convex or flat, margins weakly concave; in dorsal view, apex broadly rounded, moderately reflexed. Surface densely punctate, punctures small and moderate in size, some setose; setae minute, tawny. Mandible ( Fig. 12 ) with poorly developed molar region and poorly developed lamellae. Apex with weakly developed, ventrally produced tooth. Labrum ( Fig. 8 ) at middle apex with triangular, ventrally-produced tooth. Maxilla ( Fig. 10 ) with 2 poorly defined ridges; terminal segment of palpus elongate-oval, kidney-shaped, subequal in length to segments 1-3; basistipes with length about 1.5 times width at base. Male antenna with club 1.7-1.9 times longer than segments 2-7 combined

(rarely 1.5 times longer than 2-7 segments combined

in specimens in which segments 2-7 are fused). Fe-

male antenna with club about 1.3 times longer than

segments 2-7 combined. PRONOTUM: Surface punc-

tate; punctures minute (sparse) to moderate in size

(moderately dense) (except for small area at mid-mar-

gin that is confluent). Scutellum with surface mod-

erately densely punctate, punctures moderate in size.

ELYTRON: Surface punctate with weakly to moder-

ately defined striae. Punctures round or ocellate,

small, moderately dense, some setose; setae minute,

tawny. Striae indicated by depressed, punctate line;

punctures round or ocellate, small, moderately dense,

some setose: 2 striae adjacent to suture (neither reach-

ing apex), 4 striae on disc in male (neither reaching

apex; 4-6 striae in female), single stria laterad of

humerus in male (1-2 in female). Intervals moder-

ately densely punctate; punctures round or ocellate,

small, moderately dense or occasionally confluent,

some setose; setae minute, tawny. Odd intervals suf-

fused with castaneous color or not. Elytral sutural

Figure 25. Distribution of Microchilus species. length 6.9-8.3 times length of scutellum. PYGIDIUM:

Surface convex in lateral view, moderately densely

punctate; punctures on mid-disc irregularly rounded, moderately large, moderately dense; punctures laterally and at margin transversely elongate, moderately large to large, moderately dense (laterally) to confluent (at margin). Apical bead complete. VENTER: Mesosternum not invaginated, not forming a rounded pit. Base of first sternite at middle simple, not produced ventrally. Last sternite of male at apex with moderately deep to deep emargination (middle of emargination subequal to 1/2 length of sternite or entire length of sternite); middle of emargination rounded. LEGS ( Fig. 11 , 15, 17, 19 ): Male protarsomere I elongate (about 1.5 times longer than protarsomere II), weakly flattened dorsoventrally; protarsomeres II-III weakly elongate (slightly longer than wide), dorsal surface weakly convex; protarsomere V elongate (subequal to protarsomeres III-IV), subcylindrical (weakly flattened dorsoventrally). Female protarsomere I subequal to protarsomeres II-IV combined, shape subcylindrical; protarsomere II moderately elongate (about 1.5 times longer than wide), protarsomeres III-IV weakly elongate (slightly longer than wide), shape nearly subconical; protarsomere V slightly elongate (about 1.5 times longer than protarsomere IV), subcylindrical (weakly flattened dorsoventrally). Metatrochanter with apex not produced beyond posterior border of femur. Male metatibia with moderately developed, external carina near apical third. Female metatibia with poorly developed, external carina in basal third and well developed, external carina near apical third. Inner apical spur about 1/3 length of apical spur in male; 1/3 to 1/2 length of apical spur in female. PARAMERES ( Fig. 21-22 ): Shape asymmetrical.

Diagnosis. Microchilus lineatus is distinguished from M. rodmani by the following characters: second protarsomere elongated in the male ( Fig. 15 ) (subequal in width and length in M. rodmani [ Fig. 16 ]); male metatibia with carinae in apical third ( Fig. 17 ) (lacking external carinae in male M. rodmani [ Fig. 18 ]); female metatibia with carinae in basal third and near apical third (lacking external carinae in female M. rodmani ); pronotum lacking white, scale-like setae (sparse, white scale-like setae present on pronotum in M. rodmani ); and form of male parameres ( Fig. 21-22 ). Additional characters that separate the species are: mandible with molar region and lamellae poorly developed (moderately developed in M. rodmani ) and labrum at middle apex with triangular, ventrally-produced tooth (quadrate, ventrally produced tooth in M. rodmani ).

Distribution (Fig. 25). Southeastern Brazil in the Atlantic Coastal Forest.

Locality Data. 41 specimens examined from BMNH, CASC, CMNC, ISNB, LACM, UCCC, UNSM, ZMHB. BRAZIL (36). MINAS GERAIS (11) : Uberaba (10); no data (1). PARANA (3) : Ponta Grossa (3). SÃO PAULO (22) : Batatais (2); Itu, Fazenda Pau d’Alho (1); Sao José dos Campos (6); Yporanga (9); no data (4). NO DATA (5).

Temporal Data. January (1), February (2), October (9), November (8), December (2).

Natural History. Microchilus lineatus feeds on Aristida pallens Cav. (Poaceae) ( Ohaus 1908). The species is diurnal and can be found on vegetation during the day ( Ohaus 1900).

Remarks. Color variation in M. lineatus ranges from reddish-brown to brown, thus overlapping with color in M. rodmani . Based on locality information, M. lineatus and M. rodmani are apparently sympatric in a portion of their range (from Uberaba south to near São Paulo).

Figures

Figure 1-7. Habitus images Microchilus species and other Geniatini. 1) Microchilus lineatus, male. 2) M. lineatus, female. 3) M. rodmani, holotype male. 4) M. rodmani, allotype female. 5) Bolax foveolata Blanchard, male. 6) Leucothyreus beckeri, male. 7) Eunanus murinus Ohaus, male. Scale line = 1.0 mm.

Figure 8-14. Generic characters for members of the genus Microchilus. 8) Labrum and clypeus, frontal view of M. lineatus. 9) Mentum, ventral view of M. lineatus. 10) Right maxilla, ventral view of M. lineatus. 11) Claws, dorsal oblique view of M. lineatus. 12) Left mandible, dorsal oblique view of M. lineatus. 13) Gonocoxites, dorsal view of M. lineatus. 14) Left wing, ventral view of M. rodmani. Scale line = 0.5 mm.

Figure 15-24. Diagnostic characters of Microchilus species. 15) Right protarsomeres of male M. lineatus, dorsal view. 16) Right protarsomeres of male M. rodmani, dorsal view. 17) Right metatibia of M. lineatus, ventral view. 18) Right metatibia of M. rodmani, ventral view. 19) Right protarsomeres of female M. lineatus, ventral view. 20) Right protarsomeres of female M. rodmani, ventral view. 21-22) Parameres of M. lineatus, dorsal view and lateral view, respectively. 23-24) Parameres of M. rodmani, dorsal view and lateral view, respectively. Scale line = 0.5 mm.