Discozantaena Perkins and Balfour­Browne 1994

Perkins, Philip D., 2005, A revision of the South African endemic humicolous beetle genus Discozantaena Perkins and Balfour­Browne (Coleoptera: Hydraenidae), Zootaxa 915, pp. 1-48 : 5-6

Discozantaena Perkins and Balfour­Browne 1994

Discozantaena Perkins and Balfour­Browne 1994: 123 (type species Discozantaena genuvela Perkins and Balfour­Browne, 1994 ).

Diagnosis. Recognized by the wide and shallow antennal pocket that lacks hypomeral setae, the short maxillary palpi and legs, the 10 articles of the antenna, the reduced hydrofuge pubescence, and the two brush­like clusters of setae on the last abdominal tergum of both sexes. Most species (except D. sequentia ) are also recognized by the broadly explanate and transversely convex elytra, the wide clypeus, and the explanate pronotum which is notched on each side just before the acute posterior angle.

Description. Form: Broadly ovate, elytral disc transversely convex, pronotum explanate, elytra usually broadly explanate. Size: length/width (mm) varying from about 1.59/0.89 to 2.25/1.16.

Head broad, width about 2x length. Eyes rather small, in dorsal aspect ca. 7–8 facets in longest series. Temples each produced as minute tooth. Labrum usually set under anterior margin and at an angle to very broad clypeus. Ocelli moderately developed, subtriangular. Labroclypeal suture arcuate or weakly bisinuate. Maxillary palpus short, shorter than antenna, palpomeres 2, 3 and 4 length ratios about 3:2:5; last palpomere penicillate, length 1/2 basal width of mentum. Mentum length about 1/2 basal width; anterior margin obscured by dense setae. Genae rounded, divided by median groove, with a distinct lateral sulcus for reception of each antenna. Antennomeres 10 (5+5); pubescent club loosely articulated.

Pronotum very transverse, length about 1/2 width; sides arcuate, more stongly so near base, then turning outward to form acute process at each posterolateral angle; sides denticulate; anterior margin nearly straight except for median 1/3 broadly and shallowly emarginate, narrow hyaline border in emargination; posterior margin median 1/3 produced slightly and with very narrow hyaline border; disc with anterior transverse depression and posterior u­shaped depression; lateral depressions broad, median area of each with low rounded relief; surface with setigerous granules. Prosternum with procoxae contiguous, apex of intercoxal process visible behind coxae; area in front of procoxae nearly flat, lacking median carina, on each side with small cluster of stiff spines; antennal cavity broad, shallow and microreticulate, lacking stiff or erect marginal setae; low ridge separating cavity from inflexed margin of pronotum, ridge becoming obsolete posteriorly; no carina separating pubescent prosternal area from non­pubescent inflexed margin of pronotum; coxal cavities nearly completely closed behind. Mesosternum with longitudinal ridge on each side; intercoxal process narrow. Metasternum sometimes with anterior intercoxal ridge contiguous with mesosternal intercoxal process; metasternum short, length about equal to length of mesocoxa in brachypterous forms, longer in pterous forms; median area midlongitudinal or oval impression, sometimes very shallow. Elytra conjointly transversely quite convex; humeral umbo absent in brachypterous forms; sutural stria in posterior half; each elytron with ten rows of punctures, plus, in some species, two rows on explanate margin.

Abdomen with ventrites rather flat; hydrofuge pubescence varying among species; intercoxal ventrite small, triangular; last tergum bearing on each side a submarginal brushlike cluster of setae in both sexes. Legs short and stout, femur thickened; metafemur lateral margin arcuate; metatrochanter elongate, length slightly greater than 2x width; tarsi very short, basal three tarsomeres connate, claws short and stout. Aedeagus usually with very short parameres, inserting near base of mainpiece. Spermatheca elongate, tubular.

Antennal pocket (terminology as in Perkins, 1997) relatively wide and shallow, entirely microreticulate, with randomly distributed exocrine pores and narrow band of hydrofuge pubescence along lateral, anterior, and anteromedial margins; low, rounded hypomeral carina separates wet­ and bubble­hypomeron, carina becoming obsolete posteriorly; exocrine pores, about 25–35 in number, randomly distributed along inner margin of carina and between carina and reticulate hydrofuge; no organized clusters of pores or endapparatus, and no secretion sulcus on hypomeron; antennal pocket setae very small, about four in number, non­rigid (lie flat on cuticle in dry specimens) located at posterolateral margin of antennal pocket; prosternal antennal cleaner located near anterior margin of prosternum; no hydrofuge hairs between antennal cleaner and antennal pocket, otherwise antennal cleaner is surrounded by reticulate hydrofuge; exocrine pores located near base of antennal cleaner; periocular exocrine pores present at margin of eye; subocular antennal groove microreticulate, with numerous exocrine pores; postocular area clothed in hydrofuge pubescence; lacking specialized exocrine secretion delivery setae or sensilla.