Dichotomius (Luederwaldtinia) simplicicornis ( Luederwaldt, 1935 )

Montoya-Molina, Santiago & Vaz-De, Fernando Z., 2021, Taxonomic review of the Dichotomius (Luederwaldtinia) agenor species group (Coleoptera: Scarabaeidae: Scarabaeinae), European Journal of Taxonomy 734, pp. 1-64 : 42-44

Dichotomius (Luederwaldtinia) simplicicornis ( Luederwaldt, 1935) Fig. 14 , Map 12

Pinotus simplicicornis Luederwaldt, 1935: 340 (original description).

Pinotus simplicicornis – Blackwelder 1944: 208.

Dichotomius simplicicornis – Ratcliffe et al. 2015: 197. — Chamorro et al. 2018: 95; 2019: 132 .

Diagnosis

Dichotomius simplicicornis is separated from other species in the group by the following combination of characters: cephalic carina median tubercle higher than lateral ones, apically rounded and emarginate. Lateral tubercles short with acute on apex. Ventral clypeal process conical apically acute. Pronotum medial edge of the anterior disc declivity deeper than lateral sides, resembling two underdeveloped lobes. Elytral striae well marked, punctuation same width of striae; interstriae smooth.

Material examined

Lectotype (head and pronotum, here designated)

PERU • ♂; “Peru” [white, hw]/ “ Pinotus simplicicornis n. sp. Lueder. Det. 1934” [white, hw]/ “Fry Coll. 1905-100” [white, p]/ “34600” [white, hw]/ “ HOLOTYPE ” [red with black margins, p]; BMNH.

Additional material

PERU • 8 ♂♂, 4 ♀♀; Junín, Pichinaqui, Yaroni ; 2 Apr. 2006; A. Santibáñez leg.; CEMT .

Redescription

Male

MEASUREMENTS. Length: 20.17 mm.

HEAD. Anterior third surface transversely rugose, extending posteriorly not reaching base of cephalic carina. Interocular space smooth, with scattered deep punctures ( Fig. 14 C–D). Clypeal margin with large medial emargination separating two rounded clypeal teeth feebly angled upwards. Cephalic carina, wider than high and conical in shape ( Fig. 14D ). Median tubercle three times as high as lateral tubercles, apically rounded and emarginate. Lateral tubercles short and acute on apex ( Fig. 14C ). Ventral clypeal process conical in shape and apically acute.

PRONOTUM. Twice as wide as it is long, wider than elytra. Pronotal disc shiny and with well-impressed simple punctures, larger punctures on anterolateral edges and near posterior basal central margin.Anterior disc with sharp declivity, medial portion deeper than lateral sides, resembling two underdeveloped lobes ( Fig. 14A, D ). Hypomeron medial disc smooth and shiny, external margin bearing rows of disorganized setigerous punctures, setae all approximately of same length (see Fig. 2E ).

ABDOMEN. Prosternum surface shagreened, with scattered ocellate setigerous punctures. Mesosternum and metepisternum surface shagreened, with large ocellate setigerous punctures, separated by less than twice diameter of a puncture. Metasternum anterior surface and margins of mesocoxa microsculpture shagreened, covered by dense long setae that surrounds the margins of mesocoxa, joining the anteromedial with lateral portions of metasternum (see Fig. 2G ). Longitudinal sulcus distinctly sculpted, ending as shallow mid-fossa. Sternites with ocellate punctures along anterior margins. Pygidium delimited by incomplete margin, faded apically, large punctures restricted to basal margin, medial and apical surfaces finely punctate.

ELYTRA. Shiny, wider than long. Striae distinctly punctate separated by two times diameter of a puncture on elytral disc; punctures same width of striae. Interstriae smooth with conspicuous randomly arranged punctures.

LEGS. Metacoxa microsculpture shagreened, posterior edge covered by row of dense setigerous punctures separated by less than diameter of a puncture, setae dense. In ventral view, profemora surface with scattered well-imprinted punctation, setigerous punctation restricted to medial edge.

PARAMERES AND LAMELLA COPULATRIX. See Fig. 14 E–G.

Morphological variation

Females ( Fig. 14B )

As males except for the following characters:

HEAD. Surface completely rugose. Space between clypeal teeth less separated than in males. Genae border protruding clypeal margin. Fronto-clypeal carina bituberculate.

PRONOTUM. Narrower than elytra, gibbous.

ELYTRA. Twice as long as pronotum with shagreened microsculpture.

Remarks

The holotype has the first half of the body (head and pronotum) of a male and the second half (abdomen) of a female. As the ICZN states in Article 73.1.5 “ If a subsequent author finds that a holotype which consists of a set of components (e.g. disarticulated body parts) is not derived from an individual animal, the extraneous components may, by appropriate citation, be excluded from the holotype (material may be excluded from a hapantotype if it is found to contain components representing more than one taxon ”; therefore, we here designate the head and the pronotum as lectotype. Endemic species from Peru and individuals cited by Chamorro et al. (2018: 95, 2019: 132) from Ecuador were the rare species Dichotomius foveicollis (Kirsch, 1871) .

Figures

Fig. 14. Dichotomius simplicicornis (Luederwaldt, 1935). A–B. Dorsal habitus. A. ♂. B. ♀. C. Lateral view of the aedeagus. D. Frontal view of the male head, cephalic carina apically rounded, emarginate, lateral tubercles short and acute on the apex. E. Ventral view of the aedeagus. F–G. Lamella copulatrix. H. Pronotum arcuate viewed from above, anterior edge declivity resembling two under-developed lobes at the sides.

Fig. 2. General characters that help differentiate the species of the Dichotomius (Luederwaldtinia) agenor species group. A–D. Ventral clypeal process. A. Cordate as in D. agenor (Harold, 1869). B. Truncate as in D. sagittarius (Harold, 1869) stat. rev. C. Bifurcate as in D. belus (Harold, 1880). D. Cylindrical as in D. henripittieri sp. nov. E–F. Hypomeral characters. E. Medial disc smooth, lateral margin with multiple rows of setae as in D. amplicollis (Harold, 1869). F. Medial disc punctate, lateral margin with single row of setae as in D. tristis (Luederwaldt, 1923). G–H. Metasternum characters. G. Setigerous punctures from the medial and lateral edges joining throughout the margin of the mesocaxa as in D. enioi sp. nov. H. Setigerous punctures from the medial and lateral edges not joining throughout the margin of the mesocaxa as in D. centralis (Harold, 1869). I–J. Elytra interstriae. I. Smooth as in D. amplicollis. J. Shagreened as in D. agenor.