Microbrachida Bierig, 1939

Caron, Edilson, Souza, Maria Geralda De & Pamblona, Ana Maria Santa Rosa, 2024, Rediscovery of Microbrachida Bierig, 1939, description of a new species from the Brazilian Amazon and its potential for biological control (Coleoptera, Staphylinidae), Zootaxa 5537 (4), pp. 541-550 : 543-545

Microbrachida Bierig, 1939

( Figs 1–22 )

Type species. Microbrachida gilvicornis Bierig, 1939 (designated by monotypy).

Diagnosis. Microbrachida differs from Brachida and Probrachida by having body sublimuloid in dorsal view ( Figs 1 , 6 ); head strongly deflected ( Figs 2 , 7 ); labium without medial seta ( Fig. 10 ).

Description (based mainly on M. perniciosae ). Adult. Male. Maximum body length 1.5 mm, maximum elytral width 0.5 mm; Body sublimuloid, apex of elytra widest and abdomen tapering toward the apex ( Figs 1 , 6 ). Body sublimuloid, with somewhat pubescence, surface sculpture reticulates throughout. Head transverse, slightly wider than long; strongly deflected ( Figs 2 , 7 ); base hidden in dorsal aspect by anterior margin of pronotum; medial and lateral macrosetae absent; eyes very large, globose, prominent, coarsely faceted, extended most length of lateral margin of head; temple obsolete; infraorbital carina well developed and complete; neck carina well developed. Antenna short, reaching base of pronotum ( Fig. 1 ); scape, pedicel and antennomeres 3 and 4 subglabrous and coarse pubescence internally directed ( Fig. 18 ); fine pubescence increasing gradually on antennomeres 5 to 11, each with coarse pubescence on apical region; scape, pedicel and antennomere 3 each two times longer than wide; scape and pedicel with the same width and wider than antennomere 3; antennomere 4 shortest, transverse, slightly wider than the precedent; antennomeres 5 to 10 transverse, increasing in width toward the apex; antennomeres 11 longer than wide and slightly wider than antennomere 10. Labrum transverse, broadly emarginated on apical margin ( Fig. 8 ); pair of membranous lobe well developed; α-sensillum (a-sensillum of Sawada 1972) well developed, filiform; β-sensillum (b-sensillum of Sawada 1972) very short; ε-sensillum setose and shorter than labral setae; A.L. 1 (d1 of Sawada 1972) distant from margin of labrum and A.L. 2 (d2 of Sawada 1972) at margin of labrum; each lateral margin with three spine-like sensilla, distant from lateral margin; internal setose area absent. Mandibles asymmetrical, not bifid at apex; right with moderalely internal tooh; prostheca with finely ciliate; molar region with rows of small denticles. Maxilla with apex of lacinia obliquely truncate, with patch of numerous closely spaced teeth (spore brush of Ashe 1984) ( Fig. 9 ); setae on inner surface of lacinia in single irregular row; galea with apical setae in numerous close rows, setae filiform; palpomere 1 shortest, 2 and 3 about the same length, 4 about two-thirds length of precedent. Labium with mentum somewhat trapezoidal, twice wider than the maximum length (Fig. 107 ligula entire, broadly rounded; medial seta absent; labial palpi two-articled (1 and 2 fused), 3 about one-third length of precedent. Gular plate broad, with subparallel sides along all length. Pronotum transverse, about two times wider than long ( Figs 1 , 6 ); convex; anterior angles and sides depressed; hypomera not visible in lateral view; posterior margin slightly bisinuate, not emarginated medially; prosternum transverse, with marked transverse carina. Elytra slightly longer than pronotum ( Figs 1 , 6 ); around 1.5 times wider than long ( Fig. 19 ); apico-lateral angles markedly sinuate. Wings well-developed. Mesoventrite process extended slightly posterior of middle mesocoxal cavities ( Fig. 20 ); meso- and metaventrites processes fused, suture and isthmus absent, processes distinguished by differences in surface sculpture. Metepisternum with two setae in a single row on posterior one-third, bordered anteriorly and ventrally by carina. Tarsal formula 4-4-5; metatarsomere 1 about as long as 2. Abdomen with sides slightly convergent from base to apex ( Figs 1 , 6 ); segments III to VI with two pairs of paratergites, identical in length; segment VII with pair of very small paratergites; terga III to VI with pronounced transverse concavity; tergum VII with modified anterior margin for openings to abdominal glands, medial one-third broadly protruded; tergum IX divided into two lateral lobes, symmetrical ventral struts ( Fig. 12 ); tergum X with setal patch square, apical half with four macrosetae on each side near the posterior margin and microsetae somewhat flattened ( Fig. 12 , detail). Aedeagus typical of subtribe, cylindrical sclerotized flagellum ( Figs 13 , 22 ); apical lobe of each paramere elongate, setae unequal and not all near apex.

Female. Similar to male, tergum IX without ventral struts; hemisternite IX visible fused on tergum IX; spermatheca typical of subtribe, latero-apical plate present, neck elongate distal to latero-apical plate ( Fig. 17 ).

Remarks. Microbrachida shares with other three genera, Brachida , Probrachida and Encephalus , a broadly rounded ligula. Then, the differences from the two earlier genera are noted in the diagnosis. While Microbrachida can be distinguished from Encephalus by markedly sinuate apicolateral angles of elytra ( Figs 1 , 6 ); meso- and metaventrites processes fused and transversal suture absent ( Fig. 20 ).

Bierig (1939) also described two monotypical genera from Panama: Brachycantharus Bierig, 1939 and Neobrachychara Bierig, 1939 . In the same way as Kim & Ahn (2015), we point out here the differences among these genera and Microbrachida . Then, Microbrachida differs from Brachycantharus and Neobrachychara in having body sublimuloid and head strongly deflected (body subparallel-sided and head not deflected in Brachycantharus and Neobrachychara ( Figs 1 and 3 in Bierig 1939).

Figures

FIGURES 1–5. Microbrachida gilvicornis, holotype (FMNH). 1. Habitus, dorsal view; 2. Habitus, lateral view; 3. Labels; 4. Antennae, dorsal view; 5. Abdomen, dorsal view. Scale bars: 1, 4, 5 = 0.5mm; 2 = 0.2mm. Photo credit: Jessica Wadleigh@The Field Museum, CIL-FMNH.

FIGURES 6–7. Microbrachida perniciosae. 6. Habitus, dorsal view; 7. Habitus, lateral view; Scale bars: 1mm.

FIGURES 8–17. Microbrachida perniciosae. 8. Labrum, dorsal view; 9. Maxilla, dorsal view; 10. Labium, ventral view; 11. Tergite VII, male, dorsal view; 12. Tergite IX and X, male, dorsal view; 13. Median lobe of aedeagus, lateral view; 14. Sternite VIII, male, ventral view; 15. Tergite VIII, female, dorsal view; 16. Sternite, female, ventral view; 17. Spermatheca. Scale bars: 8, 10 = 0.03 mm; 9–16. = 0.125mm; 17 = 0.06 mm.

FIGURES 18–22. Microbrachida perniciosae. 18. Antena; 19. Elytra; 20. Meso- and Metaventrite; 21. Detail of median lobe of aedeagus; 22. Median lobe of aedeagus. Scale bars: 19–20, 22 = 100 micrometers; 21 = 10 micrometers.