Dichotomius (Luederwaldtinia) triquetrus ( Luederwaldt, 1923 )

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 : 47-48

Dichotomius (Luederwaldtinia) triquetrus ( Luederwaldt, 1923) Fig. 16 , Map 14

Pinotus triquetrus Luederwaldt, 1923:11 (original description).

Pintous triquetrus – Blackwelder 1944: 208.

Dichotomius triquetrus – Schoolmeesters 2018 (Catalogue of Life).

Diagnosis

Dichotomius triquetrus is separated from other species in the group by the following combination of characters: dorsal and ventral surface reddish to dark brown. Anterior clypeal margin with deep emargination separating two obtuse teeth. Head interocular space displaying flat punctures, resembling rough; distinct ocellate punctuation near eyes. Pronotum medial disc with fine punctures, anterolateral edges with well-impressed punctures, ocellate punctuation along margins. Elytra striae strongly marked, interstriae microsculpture shagreened

Material examined

Lectotype (here designated)

TRINIDAD AND TOBAGO • ♀; “Caparo Trinidad Heyne, Berlin-Wilm.” [white, p]/ “ Pinotus triquetrus n. sp. L̹d.det.23” [white, hw]/ “18188” [white, p] /[blue rounded label]; MZSP.

Additional material

TRINIDAD AND TOBAGO • 1 ♂, 1 ♀; St. George Co., Range, Simla Research Station , Arima Valley , N. Range ; 800 ft a.s.l.; 10º41′34″ N, 61º17′22″ W; FIT [flight interception trap]; premontane tropical rainforest; 3 Jun. 2000; S. Alistair and Ramsdale leg.; CEMT • 1 ♀; Trinidad ; 1904; F. Birch leg.; BMNH • 1 ♂; Antilles Trinidad ; Fry leg.; BMNH 1905-100 • 1 ♂; Porto Spain , Dec 1912 – May 1913; R. Thaiter leg.; MZSP .

VENEZUELA • 1 ♂; BMNH .

COUNTRY UNKNOWN • 1 ♀; Nevinson leg.; BMNH 1918-14 .

Redescription

Female

MEASUREMENTS. Length: 17.89 mm. Dorsal and ventral surfaces reddish to dark brown.

HEAD. Anterior edge surface horizontally rugose, interocular space displaying flat punctures, resembling rough; distinct ocellate punctuation near eyes. Clypeus with central deep emargination separating two acute clypeal teeth ( Fig. 16 B–C). Cephalic carina bituberculate, wider than high, tubercles obtuse apically ( Fig. 16C ). Ventral clypeal process truncate (see Fig. 2B ).

PRONOTUM. Gibbous, wider than long. Pronotal anterior disc shiny and smooth with fine, dense and wellimpressed punctures near antero-lateral sides. Uninterrupted ocellate punctures along pronotal margins ( Fig. 16B, D ). Hypomeral disc punctate; external margin bearing single row of organized long setae, approximately of same length (see Fig. 2F ).

ABDOMEN. Prosternum surface with fine microsculptured, glabrous. Mesosternum and metepisternum surface microsculpture shagreened with ocellate setigerous punctures. Metasternum setigerous punctures restricted mainly to anterior and lateral edges of mestasternal lobe, puncture diameter variable. Punctuation of antero-median edge connecting with lateral ones through margin of mesocoxa (see Fig. 2G ). Lateral edges of metasternum with ocellate, setigerous punctures separated by width of a puncture, pilosity sparse, setae short, not reaching metepisternum suture. Longitudinal sulcus clearly visible. Ocellate punctures along anterior margins of sternites. Pygidium ocellate punctation on basal edge and through lateral margins.

ELYTRA. Interstriae microsculpture shagreened (see Fig. 2J ), fine punctures randomly distributed. Striae strongly marked, ocellate punctures separated by diameter of a puncture on elytral disc ( Fig. 16D ).

LEGS. Metacoxa posterior edge bearing single row of organized ocellate punctures, separated by diameter of a puncture. Posterior margin of meta-trochanter with long setae.

Morphological variation

Males ( Fig. 16A ) are distinguished from females as follows:

HEAD. Cephalic carina higher than wide, conical in shape. Median tubercle twice as high as lateral tubercles, rounded, weakly bifurcate apically and curved posteriorly. Apex of lateral tubercles acute.

PRONOTUM. Surface covered by fine punctures, denser at antero-lateral areas; anterior disc with weak declivity.

PARAMERES AND LAMELLA COPULATRIX. As in Fig. 16 E–G.

Remarks

This is an endemic species from Trinidad.The redescription was based on the well-developed female of the MZSP and the underdeveloped female at the CEMT. The male redescription was based on the specimen in the MZSP wrongly determined by Pereira as “ Pinotus belus ” and an underdeveloped male from the CEMT. Male genitalia were extracted from the underdeveloped male at CEMT. Luederwaldt (1923) also mentioned a male specimen in the type series that could not be traced.

Figures

Fig. 16. Dichotomius triquetrus (Luederwaldt, 1923). A–B. Dorsal habitus. A. ♂. B. ♀. D. Lectotype, ♀ (MZSP). C. Lateral view of the aedeagus. D. Dorsal view of the head. E. Ventral view of the aedeagus. F–G. Lamella copulatrix. H. Elytra.

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.