Coccidotrophus Schwarz and Barber, 1921

Halstead, David G. H., 2020, New and little known Coleoptera (Silvanidae: Silvaninae) from Central and South America, Insecta Mundi 2020 (842), pp. 1-37 : 16-17

Coccidotrophus Schwarz and Barber

Coccidotrophus Schwarz and Barber 1921: 189

Discussion. This genus was erected to accommodate one species, C. socialis Schwarz and Barber, 1921 . The authors also described another species in the same paper which they placed in Eunausibius Grouvelle , E. wheeleri Schwarz and Barber, 1921 . The latter species is transferred to Coccidotrophus in the current contribution (see below). A third species, C. cordiae Barber , was described in 1928. A few years ago, Dr. M. C. Thomas sent a specimen of a new species described here as C. trinidadensis , new species, and more recently, when examining the silvanid accessions in the NHML, the author discovered another new species also described here and named Coccidotrophus platyops , new species. In addition, more detailed descriptions, including habitus and genitalia illustrations, are presented below for the three previously known species.

Biologically, Coccidotrophus is of particular interest as C. socialis , C. wheeleri and C. cordiae have all been found living with mealybugs ( Pseudococcus spp. ( Pseudococcidae )) in myrmecodermatia (cavities in plant tissue used by ants). Coccidotrophus socialis and C. wheeleri occur in fusiform swellings of the leaf petioles of young specimens (1.5–7.0 ft. high) of the ant-tree, Tachigalia paniculata Aubl. If there are no entry holes to these swellings, they are made by the adult beetles. Both adults and larvae feed on nutritive parenchyma within the swellings and on honeydew, which like ants they solicit from the mealybugs by stroking them with their antennae. Wheeler (1921) gave a very detailed and interesting account of the feeding behaviour and biology of C. socialis , a species that he found to be very common were it occurred in Guyana (then ‘British Guiana’), and also some information on the comparatively rare C. wheeleri . In addition, he included a short account of them illustrated with photographs, in his book on social insects ( Wheeler 1928). The larvae and pupae of these two species were described by Böving (1921) who confirmed their allocation to the Silvanidae . Coccidotrophus cordiae , was first discovered by Dr. W. M. Mann in Bolivia during 1921–1922 where it was attending mealybugs in hollow swellings at the base of twigs of an ant-sheltering tree, Cordia alliodora Ruiz and Pavon ( Barber 1928) . Far more recently it has been collected with mealybugs on this tree in Ecuador and Colombia (see re-description of the species below). Regarding the two new species, the only biological / habitat information available is that for C. platyops , which was collected from the tree Micropholis guyanensis in Brazil.

Diagnosis. Body elongate and overall appearance sub-cylindrical. Head with ventral antennal grooves moderately developed and slightly convergent ( Fig. 57, 63 ), antennae short with an obvious club and funiculus composed of short, robust antennomeres. Profemora broader than other femora. Tarsomeres robust and simple. Last abdominal ventrite of the male may have a large, obvious median depression ( Fig. 72 ), present in C. socialis and C. cordiae but absent in C. wheeleri , C. platyops and C. trinidadensis . Where males of C. socialis and C. cordiae have this depression, conspecific females may have an inconspicuous, slight depression. Other secondary sexual character that are present on legs of the male include the following: tibiae all with a small apical spine on proximal margin ( C. socialis ); metafemora with small prominence on proximal margin and metatibiae with a small apical spine on same margin ( C. wheeleri , Fig. 62 ); metafemora with or without a very small prominence on proximal margin, tibiae all with a small spine on inner apex ( C. cordiae , Fig. 70 ); metatibiae with an apical spine and minute teeth along proximal margins ( C. platyops , Fig. 81 ); tibiae all with a small apical spine ( C. trinadadensis , Fig. 85 ). Male genitalia have parameres that are not obviously articulated, and the ostium borders generally with a row of conspicuous rods but they may be just darkly sclerotized ( Fig. 75–77 ).

The appearance of Coccidotrophus species is most similar to that of Eunausibius Grouvelle , however Coccidotrophus species are more elongate having longer and more cylindrical elytra and longer pronota than Eunausibius species. In addition, the known Coccidotrophus all have puncturation on at least some part of the pronotum and head that is elongate and appears to be derived from pairs of punctures ( Fig. 85 ). The known Eunausibius lack such punctures, typical round punctures being found on head and pronotum.

Figures

Figures 52–63. Coccidotrophus spp., all paratypes except figure 54. 52–57) C. socialis Schwarz and Barber, male. 52) Habitus. 53) Anterior pronotal angle, semi-lateral view. 54) Pronotum (left half), variant with strongly incurved sides. 55) Antenna, enlarged. 56) Elytron, small part including sutural margin enlarged to show rows of punctures. 57) Head, part of left side to show antennal groove. 58–63) C. wheeleri (Schwarz and Barber), male. 58) Habitus. 59) Anterior pronotal angle, semi-lateral view. 60) Antenna, enlarged. 61) Elytron, small part including sutural margin to show rows of punctures. 62) Hind leg enlarged, showing small femoral prominence etc. 63) Head, part of left side to show antennal groove. Scale line = 1.0 mm.

Figures 70–74. Coccidotrophus cordiae Barber. 70) Habitus, male; Ecuador specimen. 71) antenna, enlarged. 72) Abdomen and base of metasternum of male. 73) Pronotum of female, form with more rounded sides. 74) Habitus male, holotype (Bolivia). Scale line = 2.0 mm.

Figures 80–84. Coccidotrophus platyops, new species, male holotype. 80) Habitus.

Figures 85–90. Coccidotrophus trinidadensis new species, male holotype. 85) Habitus, inset illustrations of a few paired head punctures, also antennomeres 1–2; other puncture illustrations given as examples of pronotal paired punctures and elytral strial punctures. 86) First and second abdominal ventrites. 87–90) Genitalia and associated sclerites. 87) Genitalia, without most of internal sac. 88) Paramere enlarged. 89) Internal sac. 90) Sternites 8–9. Scale lines for Figures 85–86 = 2.0 mm, for Figures 87, 89–90 = 0.2 mm.

Figures 75–79. Coccidotrophus cordiae Barber, male genitalia and associated