Hypotelus Erichson, 1839

Bortoluzzi, Sidnei, Caron, Edilson & Ribeiro-Costa, Cibele S., 2017, Revision and phylogeny of Hypotelus Erichson: a Neotropical genus of minute rove beetles (Coleoptera, Staphylinidae, Piestinae), Zootaxa 4273 (4), pp. 451-487 : 456-461

Genus Hypotelus Erichson, 1839

[13 species; Neotropical and Nearctic Regions]

Hypotelus Erichson, 1839: 31 (without included species); Erichson, 1840: 840 (first included species: pusillus , praecox ; characters); Duponchel, 1841: 57 ( H. pusillus as type species); Lacordaire, 1854: 130 (characters, notes, list of species); Fauvel, 1864: 38 (characters, key to species); Sharp, 1887: 710 (notes, Mexican and Central American species); Bernhauer & Schubert, 1910: 9 (world catalog, 7 species); Blackwelder, 1943: 41 (characters); Blackwelder, 1944: 101 (checklist of species from Mexico, Central and South America, and the West Indies); Frank, 1986: 365 (checklist of species of Florida); Newton et al., 2000: 376 (1 Nearctic species, notes, characters in key); Herman, 2001: 1785 (bibliography, complete review of literature); Navarrete-Heredia et al. 2002: 207 (notes, Mexican species, characters in key); Caron et al., 2012: 550 (new synonyms). Type species: Hypotelus pusillus Erichson, 1840 (fixed by subsequent designation by Duponchel, 1841).

Antropiestus Bernhauer, 1917: 45 (as subgenus of Piestus ); Scheerpeltz, 1952: 295 (subgenus of Piestus ); Herman, 2001: 1788 (subgenus of Piestus ); Caron et al., 2012: 551 (as junior synonym of Hypotelus ). Type species: Piestus (Antropiestus) andinus Bernhauer, 1917 (fixed by original designation).

Eccoptopiestus Scheerpeltz, 1952: 295 (as subgenus of Piestus ); Herman, 2001: 1788 (subgenus of Piestus ). Caron et al., 2012: 550 (as junior synonym of Hypotelus ). Type species: Piestus laevis Solsky, 1872 (fixed by original designation).

Diagnosis. Hypotelus may be distinguished from other Piestinae genera by a slightly convex body ( Figs. 3–4 ); antennomeres 5–11 entirely covered with microsetae and some long setae ( Figs. 25–26 ); labium with two pairs of conspicuous long setae on anterior margin near median of sclerotized plate of ligula ( Figs. 31–32 ); mentum with anterio-lateral angles conspicuously emarginate ( Figs. 31–32 ); gular sutures joined ( Fig. 6 ); prosternum with anterior margin truncate ( Figs. 6–35 ); apex of prosternal process easily visible between the procoxae ( Figs. 6 , 34– 35 ); elytra with one longitudinal stria close to elytral suture ( Fig. 3 ); hind tarsomere 5 of the same length as 1–4 tarsomeres combined ( Fig. 38 ); abdominal segments 3–6 with two pairs of paratergites ( Fig. 3 ) and abdominal tergite 7 longest, at least 1.6 times longer than tergite 6 ( Fig. 3 ).

Redescription. BL: 2.1–6.1mm, BW: 0.5–1.3mm. Body slightly convex ( Figs. 3 , 9–19 ); dorsal surface glossy; light brown to black; elytra with same color as body, lighter or yellowish (if yellowish with some darker area); usually appendages lighter than body, except mandibles. Dorsal integument of head and pronotum with dispersed fine punctures, and with undulate microstriae (microstriae sometimes less on disc or only on margins), or granulate microsculpture; elytra with dispersed fine punctures and only one longitudinal, finely punctate stria close to elytral suture ( Fig. 3 ).

Male. Head. Somewhat pentagonal in shape with front slightly deflected and supra-antennal area slightly prominent ( Fig. 5 ), some species with two slightly pointed frontal processes or long frontal processes ( Figs. 20– 24 ); eyes somewhat prominent in dorsal view and somewhat rounded in lateral view, 1.2 to 1.3 times as long as wide, 1.5 to 2 times as long as temples and with two pairs of long setae near dorsal margin ( Fig. 4 ), except in H. andinus . Antennae inserted ventrally, reaching humeral angle or almost apex of elytra ( Figs. 3–6 ); antennomeres 5– 11 entirely covered with microsetae and some long setae on apex of each antennomeres ( Figs. 25–26 ), except in H. andinus , dispersed long setae; scape longest, some specimens with a prominent tooth on inner face; antennomeres 2 and 3 of equal length or antennomere 3 longer than 2; antennomere 4 shortest; antennomeres 5–11 gradually increasing in length toward antennal apex. Labrum transverse ( Figs. 27–28 ), anterior margin with median third deeply emarginate, three pairs of long setae medially; lateral thirds with two pairs of long setae. Epipharynx dorsally short with long fringes on anterior margin ( Figs. 27–28 ). Mandibles symmetrical and curved at apex ( Fig.

29); inner margin smooth or toothed; dorsal teeth present in H. laevis ( Fig. 30 ); prostheca developed. Maxillary cardo wider than long, somewhat subquadrate and base club-shaped ( Fig. 33 ); stipes triangular; galea extending slightly beyond apex of lacinia; lacinia with dense short setae on apex; galea narrower than lacinia, dense short setae on apex and some long setae on external margin near apex; maxillary palpus with palpomere 1 shortest, palpomere 3 wider than long and 4 longer than 2 and 3 combined. Labium with ligula slightly emarginate, pointed lobe on each anterio-lateral angle and two pairs of conspicuous long setae on anterior margin near median of sclerotized plate of ligula ( Figs. 31–32 ). Mentum pentagonal in shape, 1.6 to 2 times as wide as long and anteriolateral angles conspicuously emarginate. Gular sutures joined on apical two-thirds ( Fig. 6 ).

Thorax. Pronotum wider than long, PW/PL=1.2 to 1.5; anterior angles rounded and generally slightly prominent ( Fig. 5 ); apical half with somewhat curved sides and basal half gradually narrowing toward the base (except H. laevis Fig. 18 ); with complete internal mid-longitudinal ridge and slight longitudinal median sulcus, on basal half or for entire length of pronotum ( Fig. 5 ); one pair of conspicuous setae on anterior margin. Prosternum with anterior margin truncate ( Figs. 6 , 35 ); prosternal process long and curved toward apex, posteriorly projecting and partially occult by procoxae and apex easily visible behind the procoxae ( Figs. 6 , 34–35 ); protrochantin visible externally; postcoxal hypomeral projection acute and long. Scutellum visible, developed and somewhat triangular. Elytra somewhat longer than wide, EL/BW=1.1 to 1.3, covering abdominal tergite 3 entirely, partially or not at all; apex slightly emarginate at the middle ( Figs. 3 , 9–19 ); two long setae and a series of short setae on posterior margin. Hind wings fully developed. Intercoxal process of mesoventrite about half the length of mesocoxae, acute and rounded at apex, mesocoxae narrowly separated ( Fig. 7 ); intercoxal process of metaventrite wider and slightly shorter than process of mesoventrite; posterior margin of metacoxa slightly emarginate. Procoxae transverse and contiguous ( Figs. 6 , 36 ); protrochanter small and subtriangular; profemur robust and slightly flat anteroposteriorly, protibia with apex wider than base, longitudinal row of robust spines on apical half of external margin and at apex, internal margin slightly emarginate and with longitudinal rows of robust setae, with robust spine on the internal angle of apex; tarsomeres 1–4 subequal in length, with setae at apex, tarsomere 5 longest,same length as 1–4 tarsomeres combined, slightly curved. Mesocoxae separated, each globose ( Figs. 6 , 37 ), and metacoxae contiguous ( Figs. 7 , 38 ), each transverse and subtrapezoidal; meso- and metatrochanter subtriangular; meso- and metafemur slightly flat anteroposteriorly and somewhat curved dorsally; meso- and metatibiae with apex wider than base, metatibiae longer than mesotibiae; apical two-thirds of mesotibiae and apical quarter of metatibiae with longitudinal rows of robust spines, apex with two robust spines, internal longest; metatarsus similar to anterior legs, except in one species, H. brevitarsus sp. nov. with metatarsomeres somewhat shorter and transverse ( Fig. 39 ).

Abdomen. Abdominal segments 3–6 with parallel sides ( Fig. 3 ); tergite 1 consists of a pair of triangular plates that are completely separated from each other by a submembranous and weakly pigmented area ( Fig. 40 ); tergite 2 short, slightly less pigmented than 3 and hidden under elytra; segments 3–6 with two pairs of paratergites and segment 7 with only one pair ( Fig. 3 ); abdominal segment 7 longest; tergites 4–6 on each side with some pairs of setae; sternite 1 reduced and inconspicuous ( Fig. 41 ); sternite 2 sclerotized and fused with sternite 3, each with longitudinal median carina (intercoxal), complete on sternite 2 and continued on basal half of sternite 3; tergite 8 with posterior margin truncate to rounded and with laterotergites ( Figs. 42–43 ); sternite 8 with posterior margin truncate to rounded, weakly pigmented or not, with short setae or not; tergite 9 separated by tergite 10 and with short ventral struts ( Fig. 55 ); sternite 9 composed of a single median sclerite, symmetrical, almost 3 times longer than wide, anterior margin acute, posterior margin truncate and with two pairs of long setae ( Fig. 44 ); tergite 10 at posterior margin emarginate to slightly rounded, weakly pigmented or not, with short fringes and some setae on each side ( Figs. 55–58 ). Aedeagus with median lobe curved in lateral view, with bulbous base in ventral view, parameres developed ( Figs. 59–74 ).

Female. In general, similar to male, except: posterior margin of sternite 8 variable in shape, slightly pointed to sinoidal and with a fringe of short setae ( Figs. 75–82 ); tergite 9 without ventral struts; sternite 9 as ovipositor consisting of a pair of weakly pigmented hemisternites and a pair of more apical coxites, and with many long setae on apex ( Fig. 45 ). Bursa copulatrix variable in shape and connected to ovipositor ( Figs. 83, 88, 92, 95, 100, 103, 106 ); spermathecal duct short, weakly sclerotized and inserted laterally to apically on bursa copulatrix; spermatheca very small, weakly sclerotized and sometimes difficult to find.

Sexual dimorphism. The specimens may be easily segregated into males and females observing the abdominal segments 8 and 9 in ventral view ( Figs. 46–47 ). The males have long setae at the apical margin of sternite 9, which is exposed beyond terminalia, and all females have a set of short setae (fringes) at the apical margin of sternite 8, and sternite 9 (=hemisternites) is modified in ovipositor, structure that does not present long setae as in males. These characteristics were easily seen in the major part of the specimens examined.

Some species are sexually dimorphic in relation to the frontal processes of head and antennae. The males of H. castaneus sp. nov. have a shorter distance between the pointed frontal processes than females ( Figs. 20–21 ); in H. laevis , the pair of frontal processes is generally more developed in males than females ( Figs. 23–24 ). In some species, the males have longer antennae than the females ( Figs. 25–26 ), longest setae on alternated antennomeres and there is a prominent tooth on inner face of scape.

Distribution. Nearctic region: United States of America (only H. pusillus , previously cited as H. hostilis ). Neotropical region: Mexico, Guatemala, Costa Rica, Panama, Colombia, Venezuela, French Guiana, Ecuador, Peru, Bolivia, Brazil, Paraguay and the Caribbean islands ( Cuba, Jamaica, Dominican Republic, Saint Vincent and the Grenadines, Grenada and Trinidad and Tobago) ( Figs. 112–114 ).

Hypotelus is a Neotropical genus sensu Morrone (2014). The single species in the Nearctic region occurs in the southeast of Florida ( Fig. 112 ).

Biological notes. The species of Hypotelus , like other species of Piestinae , are commonly found in decomposing organic material, mainly under the bark of trees. Hypotelus has been found on or under bark of decaying logs, on a rotten palm, in leaf litter, in cactus and in bamboo shoots. Hypotelus species have also been collected by flight intercept and Malaise traps, Berlese and Winkler extraction of leaf litter, and in pitfall traps.

Key to species of Hypotelus (except H. micans here considered as species inquerenda)

1. Supra-antennal area visibly prominent ( Fig. 19 )............................................................. 2

- Supra-antennal area slightly prominent ( Fig. 5 )............................................................. 4

2. Disc of pronotum with large and deep depression............................................ H. andinus ( Fig. 19 )

- Disc of pronotum without large and deep depression.......................................................... 3

3. Frontal processes as long as antennal scape ( Fig. 23 ); antennomeres 5–10 subquadrate and well-developed dorsal teeth on the mandibles ( Fig. 30 )...................................................................... H. laevis ( Fig. 18 )

- Frontal processes shorter, about half-length of antennal scape ( Fig. 22 ); antennomeres 5–10 longer than wide and without dor- sal teeth on the mandibles..................................................... H. corniculatus sp. nov. ( Fig. 16 )

4. Head with frontal processes, very slight ( Figs. 20–21 , arrow)........................... H. castaneus sp. nov. ( Fig. 14 )

- Head without frontal processes ( Fig. 5 ).................................................................... 5

5. Elytra evidently differing in color from the pronotum, yellowish or reddish ( Figs. 3 , 17 )............................. 6

- Elytra equal in color or slightly lighter than the pronotum ( Figs. 10, 12 )........................................ 11

6. Body brownish and elytra yellowish ( Fig. 3 )................................................................ 7

- Body dark brown and elytra reddish ( Fig. 17 )............................................. H. marginatus ( Fig. 17 )

7. Elytra with basal darker area forming a large inverted triangle reaching the middle of elytral suture ( Fig. 13 ); antennomeres 5– 10 wider than long........................................................... H. melanodelta sp. nov. ( Fig. 13 )

- Elytra with different color pattern, not above; antennomeres 5–10 longer than wide................................. 8

8. Elytra with basal and apical transverse darker areas; male with apex of median lobe of aedeagus curved as a hook ( Fig. 73 ); female with bursa copulatrix forming a ring ( Fig. 106 ); no sexual dimorphism on antennae...................................................................................................... H. scheerpeltzi sp. nov. ( Fig. 11 )

- Elytra with only basal transverse darker area; male with apex of median lobe if curved, not as a hook; female with bursa copu- latrix rounded ( Fig. 83 ); sexual dimorphism on antennae...................................................... 9

9. Male sternite 8 with posterior margin weakly sclerotized ( Fig. 52 ); female sternite 8 with posterior margin rounded ( Fig. 76 )..................................................................................... H. insulanus ( Fig. 9 )

- Male sternite 8 with posterior margin strongly sclerotized ( Fig. 51 ); female sternite 8 with posterior margin slightly pointed at the middle or somewhat truncate........................................................................ 10

10. Male without tooth on antennal scape; tergite 10 weakly sclerotized on lateral and posterior margin ( Fig. 58 ); female sternite 8 with posterior margin somewhat truncate ( Fig. 80 ). Usually with hind tarsomeres shorter and transverse............................................................................................ H. brevitarsus sp. nov. ( Fig. 15 )

- Male generally with a tooth on antennal scape; tergite 10 weakly sclerotized only on posterior margin ( Fig. 55 ); female sternite 8 with posterior margin slightly pointed at the middle ( Fig. 75 )................................... H. pusillus ( Fig. 3 )

11. Head and pronotum similar in color; male sternite 8 with posterior margin somewhat three-pronged at the middle ( Fig. 53 ); female sternite 8 with posterior margin sinuous ( Fig. 78 )...................................... H. testaceus ( Fig. 12 )

- Head darker than pronotum; male sternite 8 with posterior margin rounded; female sternite 8 with posterior margin rounded..................................................................................... H. praecox ( Fig. 10 )

The species of Hypotelus are arranged below in alphabetical order.

Figures

FIGURE 112. Geographical records of Hypotelus pusillus: United States of America, Mexico, Cuba, Jamaica, Guatemala, Costa Rica, Panama, Saint Vincent and the Grenadines, Grenada, Trinidad and Tobago, Colombia, Venezuela, French Guiana, Peru, Bolivia, Brazil and Paraguay. Countries without dots but colored represent the occurrence but no locality given.

FIGURE 113. Geographical records of Hypotelus. Hypotelus laevis, Bolivia and Peru; H. micans, Brazil; H. praecox, Colombia and Ecuador; H. castaneus sp. nov., Costa Rica, Panama, Colombia, Venezuela and Peru; H. scheerpeltzi sp. nov., Peru. Countries without dots but colored represent the occurrence but no locality given.

FIGURE 114. Geographical records of Hypotelus. Hypotelus andinus, Colombia, Ecuador and Bolivia; H. insulanus, Caribbean islands; H. marginatus, Colombia, Venezuela and Guatemala; H. testaceus, Panama; H. brevitarsus sp. nov., Panama. Countries without dots but colored represent the occurrence but no locality given.

FIGURES 3 – 8. Hypotelus pusillus, male. 3, habitus, dorsal view; 4, habitus, lateral view; 5, head and pronotum, dorsal view; 6, head and pronotum, ventral view; 7, meso and metaventrite, ventral view; 8, abdomen, ventral view. Scale bars: Figs. 3 – 4, 8 = 1 mm; Figs. 5 – 7 = 0.5 mm.

FIGURES 25 – 35. 25 – 27, Hypotelus pusillus. 25, antenna, male; 26, antenna, female; 27, labrum, dorsal view, left epipharynx and right setae removed; 28, H. castaneus sp. nov., labrum, dorsal view, left epipharynx and right setae removed; 29, H. pusillus, mandibles, dorsal view, right prostheca removed; 30, H. laevis, mandibles, dorsal view, right prostheca removed; 31, H. pusillus, labium, ventral view, left setae of the ligula and right setae of the mentum removed; 32, H. castaneus sp. nov., labium, ventral view, left setae of the ligula and right setae of the mentum removed; 33, H. pusillus, maxilla, ventral view; 34 – 35, H. pusillus, pronotum, lateral and ventral view, respectively. Scale bars: Figs. 25 – 26 = 0.5 mm; Figs. 27 – 33 = 0.125 mm; Figs. 34 – 35 = 0.25 mm.

FIGURES 36 – 47. 36 – 38, Hypotelus pusillus. 36, anterior leg, posterior view; 37, median leg, posterior view; 38, hind leg, posterior view. 39, H. brevitarsus sp. nov., metatarsus, lateral view. 40 – 45, H. pusillus. 40, tergites 1 – 3, dorsal view; 41, sternites 1 – 3, ventral view; 42, tergite 8, female, dorsal view, setae removed (drawn under microscope slides, plates were separated); 43, sternite 8, lateral view; 44, sternite 9, male, ventral view; 45, ovipositor, female, ventral view. 46 – 47, H. castaneus sp. nov. 46, abdominal segments 7 – 9, male, ventral view; 47, abdominal segments 7 – 8, female, ventral view. Scale bars = 0.125 mm, except Fig. 40 = 0.25 mm and Figs. 46 – 47 = 0.5 mm.

FIGURES 9 – 19. Habitus, dorsal view. 9, Hypotelus insulanus, syntype, male; 10, H. praecox, lectotype, female; 11, H. scheerpeltzi sp. nov., holotype, male; 12, H. testaceus, syntype, male; 13, H. melanodelta sp. nov., holotype, female; 14, H. castaneus sp. nov., holotype, male; 15, H. brevitarsus sp. nov., holotype, male; 16, H. corniculatus sp. nov., holotype, female; 17, H. marginatus, syntype, male; 18, H. laevis, male; 19, H. andinus. Scale bars = 1 mm.

FIGURES 20 – 24. Head and pronotum, dorsal view. 20, Hypotelus castaneus sp. nov., male; 21, H. castaneus sp. nov., female; 22, H. corniculatus sp. nov., female; 23, H. laevis, male; 24, H. laevis, female. Scale bars = 0.5 mm.

FIGURES 48 – 58. Tergites and sternites of males in dorsal and ventral view, respectively and right setae removed. 48, Hypotelus pusillus, tergite 8; 49, H. scheerpeltzi sp. nov., tergite 8; 50, H. castaneus sp. nov., tergite 8; 51, H. pusillus, sternite 8; 52, H. insulanus, sternite 8; 53, H. testaceus, sternite 8; 54, H. castaneus sp. nov., sternite 8; 55, H. pusillus, tergites 9 and 10; 56, H. insulanus, tergite 10; 57, H. castaneus sp. nov., tergite 10; 58, H. brevitarsus sp. nov., tergite 10. Scale bars = 0.125 mm.

FIGURES 59 – 74. Aedeagus, for each species with lateral view and ventral view, respectively. 59 – 60, Hypotelus pusillus; 61 – 62, H. insulanus; 63 – 64, H. marginatus; 65 – 66, H. testaceus; 67 – 68, H. praecox; 69 – 70, H. brevitarsus sp. nov., parameres removed in ventral view; 71 – 72, H. castaneus sp. nov.; 73 – 74, H. scheerpeltzi sp. nov. Scale bars = 0.125 mm.

FIGURES 75 – 82. Sternite 8 of females in ventral view, right setae removed. 75, Hypotelus pusillus; 76, H. insulanus; 77, H. marginatus; 78 H. testaceus; 79, H. melanodelta sp. nov.; 80, H. brevitarsus sp. nov.; 81, H. castaneus sp. nov.; 82, H. scheerpeltzi sp. nov. Scale bars = 0.125 mm.

FIGURES 83 – 108. Tergites in dorsal view, right setae removed, and genitalia of female. 83 – 84, Hypotelus pusillus. 83, tergite 9, 10 and bursa copulatrix; 84, spermatheca. 85 – 86, H. insulanus. 85, tergite 10; 86, spermatheca. 87, H. marginatus, spermatheca. 88 – 90, H. testaceus. 88, bursa copulatrix; 89, tergite 10; 90, spermatheca. 91, H. melanodelta sp. nov., spermatheca. 92 – 94, H. praecox. 92, bursa copulatrix; 93, tergite 10; 94, spermatheca, 95 – 97, H. castaneus sp. nov. 95, bursa copulatrix; 96, tergite 10; 97, spermatheca. 98 – 99, H. brevitarsus sp. nov. 98, tergite 10; 99, spermatheca. 100 – 102, H. corniculatus sp. nov. 100, bursa copulatrix; 101, tergite 10; 102, spermatheca. 103 – 105, H. laevis. 103, bursa copulatrix; 104, tergite 10; 105, spermatheca. 106 – 108, H. scheerpeltzi sp. nov. 106, bursa copulatrix; 107, tergite 10; 108, spermatheca. Scale bars = 0.125 mm.