Symmela opaca Erichson, 1835

Pacheco, Thaynara L., Wipfler, Benedict, Monné, Marcela L. & Ahrens, Dirk, 2022, The genus Symmela Erichson, 1835 (Coleoptera, Scarabaeidae, Sericini): taxonomy and phylogenetic analysis, Journal of Natural History 56 (9 - 12), pp. 607-705 : 674-677

Symmela opaca Erichson, 1835

( Figures 22 , 29 (d), 31(f), 32(h))

Symmela opaca Erichson, 1835: 264 (original description); Blanchard 1850: 85 (catalogue); Burmeister 1855: 134 (revision); Harold 1869: 1127 (checklist); Frey 1973: 324 (key); Evans 2003: 49; Evans and Smith 2005: 31, 2007: 31, 2009: 31 (checklist)

Type material examined

Lectotype (here designated). ♂ ‘24980/ opaca Brasil. Setl./ Typus’ ( ZMHB) . Paralectotypes: 1 ♂ ‘24981/ Brasil Sello / Var ./ Typus/ Symmela opaca, Er. [type written]’ ( ZMHB), 4 ♂♂, 3 ♀♀ ‘ Brasil Sello Nr . 24980/ Typus/ Berlin/ Symmela opaca, Er. [type written]’ ( ZMHB), 1 ♂ ‘ Brasil Sello Nr . 24980/ P. Typus/ mutabilis Mos. det. G. Frey, 196’ ( CF / NHMB).

Additional material examined

2 ♂♂ ‘ Rio Verde GO-BRASIL XI-1998 Col . J . Carlos / 36 Neotropical Sericini spec.’ ( CEMT) , 1 ♀ ‘ Rio Verde GO-BRASIL XII-1996 Col . J . Carlos .’ ( CEMT), 1 ♀ ‘ Rio Verde GO-BRASIL XI-1999 Col . J . Carlos .’ ( CEMT), 1 ♂ ‘ Vila Velha – PR Brasil 3 .II .1968 Pe . J.S. Moure / DZUP 311533’ ( DZUP), 1 ♂ ‘ Symela opaca Brésil 2/2’ ( MNHN), 1 ♂ ‘ Symela opaca Brésil 1/2’ ( MNHN) .

Redescription

Length: 5.1 mm. Elytral length: 3.4 mm. Width: 2.8 mm. Head black, dull and shiny, with erect, sparse setae. Labroclypeus as wide as frons, subtrapezoidal; surface flat; plain, without an anterior concavity on each side; anterior margin convex, strongly reflexed, with a rim of dense, short setae behind anterior margin; lateral margin not incised anteriorly; punctation of surface posteriorly dense; suture between labrum and clypeus invisible. Smooth area in front of eye distinctly separated from frons by a suture. Frons anteriorly flat, punctation irregular, sparse. Ocular canthus with terminal setae, ratio of length of ocular canthus/eye diameter: 1/3. Eyes evenly spherical, ratio of diameter/ interocular width: 0.49. Antenna with eight antennomeres. Antennal club with three antennomeres, blackish, straight; width of antennal lamella equal to width of antennomeres of funiculus; apical lamella subequal to basal and median ones; length ratio of antennal club vs remaining antennomeres combined: 1/1.5; length ratio of third vs fourth antennomere: 1/3; fourth antennomere without lateral projection; length ratio of fifth vs fourth antennomere: 1/5. Labrum anteriorly bluntly angled on each side, concave at middle. Setae on mentum moderately dense.

Head and pronotum without copper iridescent shine. Pronotum unicoloured, dull but iridescent, black; widest at middle, width subequal to width of elytral base at humerus; anterior marginal line not interrupted medially, posterior marginal line absent; lateral margin not serrated, generally bent at middle, otherwise straight, behind anterior angles straight, posteriorly straight; setae of lateral margin sparse; basal margin evenly curved; transverse impression beside basal margin absent; anterior angles produced, sharply pointed; antero-lateral and postero-lateral angles not flattened dorso-ventrally; posterior angles blunt; surface without median longitudinal impression, transversal furrows or setae; punctation on disc dense, simple and fine, without well-defined impunctate areas. Scutellum without punctures.

Elytra bicoloured, blackish brown in major part, light humeral spot; surface opaque, without setae and microsculpture; striae and intervals distinct; punctation between striae sparse, diameter of punctures compared to those of striae equal; intervals flat; posterior edge convex; apical margin chitinous, without microtrichomes.

Abdomen: sternites flat in sagittal plane; lateral carina absent; first visible ventrite with row of setae on posterior edge; second visible ventrite with row of setae in medial region; basal ventrites medially with half length as laterally; ultimate and penultimate apical ventrites simple and flat; apical ventrite short (as long as preceding ventrite); penultimate apical ventrite with row of setae like preceding one; beside the robust row of setae, almost glabrous. Pygidium weakly convex.

Legs blackish and yellow. Ratio of length of metepisternum/metacoxa: 1/1.4. Metacoxa entirely plain, without elevated lateral longitudinal carina; without longer lateral bristles, with setae on basal surface, posterior margin densely setose. Metafemur with posterior margin straight. Metatibia widest at apex; ratio of width/length: 1/2.89; dorsal margin carinated, smooth; interior surface more or less glabrous; median longitudinal punctation present on interior surface; interior margin of apex sharply and deeply truncate towards ventral margin; punctation on entire lateral face present; beside dorsal margin without a row of robust setae along entire length; basal group of spines reduced to a single robust spine; distal groups of spines disposed at two-thirds of metatibia length; ventral margin not serrated. Dorsal surface of tarsi glabrous, with dense punctures. Length ratio of dorsal tibial spur/first metatarsomere: 1/1.5. Metatarsi at apex weakly widened; first tarsomere straight, its length shorter than second and third tarsomeres combined; laterally not carinate; ventral margin serrated; ventral margin glabrous; medial face glabrous. Protibia with two indistinct teeth; spur curved interiorly. First protarsomere straight, its length subequal to second and third combined; width ratio of first protarsomere vs second protarsomere: ca. 2/1; second protarsomere enlarged; third and fourth protarsomere elongate and narrow (distinctly longer than wide); fifth protarsomere circular in cross section, a little shorter than third and fourth protarsomere combined. Protarsal claws asymmetrical, shape of inner protarsal claw bifid, apex of basal tooth of inner protarsal claw convex.

Aedeagus: Figure 22 (d,e).

Figures

Figure 22. Symmela opaca Erichson, 1835, lectotype ♂. (a) Habitus, dorsal view; (b) habitus, lateral view; (c) labels; (d) parameres, dorsal view; (e) aedeagus, lateral view. Scale bars: a, b = 1 mm; d–e = 0.5 mm.

Figure 29. Distribution map of the Symmela species.