Dichotomius (Luederwaldtinia)

Nunes, Rafael V. & Vaz-De-Mello, Fernando Z., 2013, New brachypterous species of Dichotomius Hope, with taxonomic notes in the subgenus Luederwaldtinia Martínez (Coleoptera: Scarabaeidae: Scarabaeinae), Zootaxa 3609 (4), pp. 411-420 : 417-418

Key for identification of species groups in the subgenus Luederwaldtinia

We define here thirteen species groups, named after the older (or only) included species: D. agenor , D. assifer , D. batesi , D. carbonarius , D. crinicollis , D. eucranioides , D. geminatus , D. inachus , D. muticus , D. nisus , D. sericeus , D. speciosus , and D. superbus . The main changes in these groups from previous treatments are 1) the incorporation of Luederwaldt’s (1936) D. micans species group into the D. crinicollis species group; 2) the incorporation of the D. interstitialis species group into the D. carbonarius species group (see above); 3) the splitting of the D. geminatus species group from the D. inachus species group; and 4) the addition of three monobasic groups, D. superbus (see above), D. muticus (from the D. inachus species group), and D. eucranioides (from the D. assifer species group).

We stress that we consider those groups as a starting point for further taxonomic reviews in Luederwaldtinia . Currently, the D. crinicollis , D. speciosus , and D. assifer species groups and the positioning of D. superbus are under review by other authors. We do not include a list of species of each group since there are many types to be examined. However, we are confident on the names used here as we have either examined type specimens or photographs of type specimens, or have conclusive information from the original descriptions. Following key is based on characteristics of both sexes but mainly on male characters. Females are distinguished from males by the last abdominal sternite, which is expanded or at least not shortened medially as in males. When not specified on the key, characters fit for both sexes.

1 Tooth delimiting clypeogenal junction or positioned near it ( Figs. 2 A, 2B)........................................ 2

- Clypeogenal junction lacking tooth...................................................................... 3

2 Clypeal margin crenulate ( Fig. 2 A). Males with strong transversal carina on head with width subequal to interocular space. Male pronotal disc delimited anteriorly by four gibbosities. Female pronotal disc with two lateral groups of ocellate punctures. Pronotum of both sexes with longitudinal sulcus filled with ocellate punctures. Pronotum wider than elytra. Elytral suture fused. Hind wing reduced, flightless species................................................................................................... D. eucranioides species group: Dichotomius eucranioides Pereira & D’Andretta

- Clypeal margin smooth. Males with transversal carina on head higher than wide. Pronotal disc smooth, transversally roughened at most. Pronotum with simple longitudinal sulcus lacking ocellate punctures. Metasternal borders, mesepisternum, and hypomeron with abundant red pilosity ( Fig. 2 D). Pilosity of hypomeron generally curved upwards.................................................................................................... D. crinicolllis species group

3 Posterior pronotal margin with well-defined fovea with sharp edges at each posterior angle. Pronotum evenly rounded in both sexes ( Fig. 2 F).................................................................. D. sericeus species group

- Posterior pronotal margin lacking foveae.................................................................. 4

4 Hypomeron with a well-defined anterior excavation delimited by a dense brush of long, red setae. Male head with high transverse carina, pronotum with one or two median lobes delimiting anterior depression............. D. assifer species group

- Hypomeron lacking anteromedial excavation, or excavation very shallow and without medial setal brush............... 5

5 Body shiny metallic red, purple, blue, green, and/or gold. Metasternal disc concave. Male head with transverse carina bearing single horn at each end ( Fig. 2 G); pronotum with a central, well-defined, usually bifurcate lobe. Pronotal disc finely punctured. Length less than 16 mm .......................................................... D. speciosus species group

- Variable color and shiny. Metasternal disc convex. If transversal carina is present on head, then it does not have single horns at each end. Pronotum with variable shape, never with a central bifurcate lobe. Variable length.......................... 6

6 Green to copper color. Pronotum with strong anterior depression with bilobed summit ( Fig. 2 E). Male head with conical horn, female with two closely set tubercles............................................ Dichotomius superbus (Felsche)

- If body color is green to copper, than pronotum is simple, lacking lobe or anterior depression. If pronotal has anterior depressions or lobes, then body color is black or brown............................................................ 7

7 Male head with high transverse carina bearing strong medial tooth. Female head with transverse bituberculate carina, lacking medial tooth. Pronotum of both sexes simple, at most with a small knob on anterior portion and with fine punctures......................................................................................... D. agenor species group

- Male and female head variable, but never with transverse carina bearing medial tooth. If the head has a head transverse carina, then the pronotum bears large punctures, strong knobs, or depressions or the elytra is chagreened...................... 8

8 Metasternal sides, mesepisternum, and hypomeron with dense, long, red to tan pilosity. Pronotum of large males with welldefined anterior depression bearing large punctures anteriorly delimited posteriorly by bilobed knob. Males with left paramere of aedeagus with strong apical hook ( Fig. 2 C).................... D. nisus species group: Dichotomius nisus (Olivier)

- Dense and long red to tan pilosity lacking in one or more of the following areas: mestasternal sides, mesepisternum, or hypomeron. Pronotum of large males with at most weakly-defined anterior depression, lacking puncturing and delimited posteriorly by weakly-defined knob. Males with left paramere lacking apicolateral hook............................... 9

9 Pronotal disc with ocellate punctures ( Fig. 1 E, see pronotal disc)............................ D. batesi species group

- Pronotal disc without ocellate punctures. Ocellate punctures might occur on anterior angles or pronotal margins......... 10

10 Dull black to green-copper metallic species. Pronotum (except sometimes on disc) and elytra evenly chagreened (20X) ( Fig. 2 I). Head with either a conical horn, a pair of closely-set tubercles, or a short transverse carina..................................................................................................... D. carbonarius species group

- Dorsal surface black, smooth and shiny (if somewhat opaque on elytra, opacity due to punctures or reticulation and not to chagreened). Head generally with a conical horn or tubercle, or simply flat; if with a pair of closely-set tubercles then dorsum strongly shiny........................................................................................ 11

11 Hypomeron laterally with sparse, long setae. Hypomeral disc not covered by setae............. D. inachus species group

- Hypomeron laterally with dense, long setae. Most of surface of the hypomeral disc covered with setae.................. 12

12 Head with a central horn, tubercle, or knob.......................................... D. geminatus species group

- Head flat, without tubercle, horn, or knob............ D. muticus species group ... Dichotomius muticus (Luederwaldt)

Figures

FIGURE 1. Dichotomius mysticus (A) dorsal habitus; (B) dorsal view of genitalia; (C) hind wing; and (D) tarsi and tarsal claw (indicated by black arrow). Dichotomius vidaurrei (E) dorsal habitus; (F) dorsal view of genitalia; and (G) hind wing. Scale bar = 1.5 mm.

FIGURE 2. Dichotomius eucranioides (A) black arrow indicating crenulated clypeal margin; D. sexdentatus (B) black arrow indicating tooth or protuberance on clypeogenal junction (this is also seen on D. eucranioides); D. nisus (C) black arrow indicating the asymmetry of the parameres; D. crinicollis (D) black arrows indicating pilosity on the hypomeron; D. superbus (E) white arrow indicating gibbosities on the pronotum; D. schiffleri (D. sericeus species group) (F) white arrow indicating a fovea on the posterior angle of the pronotum; D. speciosus (G) black arrows indicating cephalic transversal carina; D. agenor (H) black arrow indicating male cephalic carina; D. glaucus (D. carbornarius species group) (I) elytra microsculpture.