Amazonothops aslaki gen. et sp. nov.

From all other genera of Staphylininae the new genus can be recognized based on the following characters: antennomere 2 1.6× wider than antennomere 3; antennomere 11 3× longer than antennomere 10; penultimate segment of maxillary palpi large, covered in short setae, approximately 2× the length of apical segment; apical segment of maxillary and labial palpi aciculate. Head with ‘infraorbital ridges’ straight, extended to base of mandibles; postgenal ridge absent; frontoclypeal suture present; mesoventrite with transverse ridge present (incomplete medially); mesotrochanter and first mesotarsomere of males with black combs; tarsal formula 5-5-5; empodial setae long and parallel-sided; apical edge of sternites III to VI with randomly distributed acute projections; tergites VII and VIII with broader, foliose setae in addition to the usual acuminate, simple setae; apparent fusion of tergite X to lateral tergal sclerites in males.

The differential diagnosis is based on the recovered phylogenetic position of Amazonothops and its strong resemblance to the Amblyopinini genus Heterothops. Amazonothops differs from Atanygnathus Jacobson, 1909 (Tanygnathinini) in the number of tarsal segments (5-4-4 in Atanygnathus); short genae and normal shape of the apical labial and maxillary palpomere (extremely elongate and distinctly converging to apex in Atanygnathus); absence of dorsal setae on the apical tarsomere (present in Atanygnathus). It should be noted that some species of Atanygnathus have combs on the profemora (Adam Brunke, personal communication). Amazonothops differs from species of Holisus Erichson, 1839 (Hyptiomini) in the pronotal hypomeron strongly inflexed, not visible in lateral view and without longitudinal middle carina (visible in lateral view and with middle carina in Holisus), presence of empodial setae (absent in Holisus) and general appearance and habitus (Holisus is distinctly dorso-ventrally flattened with coarse punctation). Amazonothops differs from the genus Natalignathus Solodovnikov, 2005, a hitherto unrecognized possible member of the same clade (see Discussion below) in the smaller body, short genae and much lesser elongate mouthparts, absence of dorsal setae on the apical tarsomere (present in Natalignathus) and presence of the combs. Amazonothops differs from Heterothops and other genera of Amblyopinini in presence of the frontoclypeal suture; antennomere 3 distinctly smaller than antennomeres 2 and 4; mesosternum with transverse ridge present (incomplete medially); apical edge of sternites III to VI with randomly distributed acute projections; tergites VII and VIII with broader, foliose setae in addition to the usual acuminate, simple setae; and apparent fusion of tergite X to lateral sclerites in males.

Habitus as in Fig. 2. Body dark brown-black; antennae and legs yellowish. Measurements (all in mm): HW = 0.31; PL = 0.38; PW = 0.48; FB = 1.00; EW = 0.55; TL = 2.19.

Figure 2. 

Habitus of Amazonothops aslaki gen. et sp. nov. Scale bar: 1 mm.

Head. Dorsal surface with weak transverse microsculpture. Neck indistinct; nuchal ridge absent dorsally, present laterally, extended as ‘infraorbital ridge’ towards base of mandibles. Frontoclypeal suture present. Frontoclypeal puncture present (Brunke et al. 2019: fig. 1). Anterior and posterior frontal punctures present (Brunke et al. 2019: fig. 1). Single basal puncture present (Brunke et al. 2019: fig. 1). Eyes occupying two thirds of the side of head; temples indistinct. Antennae (Fig. 3A) inserted close to margin of eye. Antennomeres 1 to 3 setiferous; 4 to 11 setiferous and with tomentose pubescence. Antennomere 2 1.6× the width of antennomere 3; antennomere 3 half the size of antennomere 2; antennomere 11 elongate, three times as long as antennomere 10. Gula widest in anterior half; gular sutures separated along entire length; postgenal ridge absent. Maxillary palpi four-segmented (Fig. 3B; apical segment acicular, about a third of the length of the penultimate palpomere; penultimate segment widest at middle; covered with setae. Labial palpi three-segmented (Fig. 3C); apical segmented acicular. Labrum transverse, complete, without emargination. Mandibles simple, crossing in resting position, without large teeth.

Figure 3. 

Morphology of Amazonothops aslaki gen. et sp. nov. A antennae B maxillary palpi C labial palpi D meso- and metathorax E mesothorax F protergal gland G tergite II H sternite III (apical edge). LP, Labial palpomere; MP, Maxillary palpomere; Pu, punctures; TR, Transverse ridge.

Prothorax. Pronotum widest in posterior third. Dorsal surface with weak transverse microsculpture and two pairs of punctures in dorsal series (one puncture near posterior margin and one distad of that); hypomeron strongly inflexed (not visible in lateral view). Basisternum with weak longitudinal ridge in posterior half, without punctures or setae. Post-coxal process absent.

Scutellum with anterior transverse ridge only, impunctate, glabrous. Elytra widest posteriorly. Hind wings fully developed, posterior edge with fringe of setae; veins CuA and MP4 fused; vein MP3 present. Mesoventrite (Fig. 3D) with five large punctures medially (Fig. 3D; Pu), with rounded ventral process and with transverse ridge, incomplete medially (Fig. 3E).

Abdomen. Protergal glands elongate, fringed by setae (Fig. 3F). Tergites with anterior transverse carina only. Tergite II as in Fig. 3G. Sternite III with evenly curved transverse carina, slightly projected medially. Tergite VII with white fringe along posterior edge. Apical edge of sternites III to VI with randomly distributed acute projections (Fig. 3H). Tergites VII and VIII with broader, foliose setae in addition to the usual acuminate, simple setae (Fig. 4A–C).

Legs. Tarsal formula 5-5-5. Both sexes with protarsomeres 1 to 4 transverse. All tarsal empodia with long, parallel-sided setae (Fig. 4D, E).

Male. Protarsomeres 1 to 4 with white adhesive setae ventrally. First mesotarsomere with black comb comprising 11–14 articles (Fig. 4F, H). Mesotrochanter with black comb comprising 7–11 articles (Fig. 4G, H). The number of articles within each comb varies between individuals.

Female. Protarsomeres 1 to 4 only with usual setae ventrally, white adhesive setae absent. No combs.

Figure 4. 

Morphology of Amazonothops aslaki gen. et sp. nov. A tergite VII B tergite VII C abdominal apex (tergites VII and VIII) D empodium of mesotarsi E empodium of metatarsi F mesotarsi (male) G mesotrochanter (male) H mesoleg (male). ES, Empodial setae; FS, Foliose setae; MS, Mesotarsomere; MSTr, Mesotrochanter; SS, Simple setae.

Based on the specimens studied here, the new genus is restricted to the lowland areas of the Amazonian basin of Peru.

Based on the available label data, the genus occurs in forested areas (100–420 m elevation) and has so far only been collected by flight intercept traps.

The genus name is a combination of ‘Amazon’ and the genus name Heterothops, which the new genus strongly resembles superficially.

The new genus is certainly morphologically distinct among other members of the subfamily Staphylininae and family Staphylinidae. Noteworthy is the secondary sexual dimorphism exhibited by Amazonothops. In males, the mesotrochanter and first mesotarsomere have distinct black combs which are completely lacking in females (Fig. 4F, G, H). The function, if any, of the combs remains unknown but very similar combs are commonly found within Amblyopinini, e.g., recently illustrated for Myotyphlus Fauvel, 1883 (Solodovnikov and Jenkins Shaw 2017).

Holotype. Male ‘PERU: Amazonia, Loreto region, Requena Province, 3km E of Jenaro Herrera, 100–200 m, 4°53.914'S, 73°38.689'W, 24–28.VIII.2017, rainforest, FIT close to logs, A. Hansen, D. Zyla, M. Chani-Posse PER17-11i’ (NHMD). Paratypes. 2 males (of them 1 DNA vouchered), 1 female, same locality but 4°53.210'S, 73°38.921'W, 7–10.IX.2017, rainforest, FIT near wetland/Mauritia flexuosa L.f. palms, leg. A. Hansen, J. Kypke, A. Solodovnikov (PER 17-22f) (NHMD). Male (coated for SEM and mounted on two stubs), same data, but FIT near creek (PER17-22l) (NHMD). 1 male, disarticulated and slide mounted, ‘PERU: Dept. Madre de Dios: Pantiacolla Lodge, Alto Madre de Dios R. 12°39.3'S, 71°13.9'W 420m 14-19-XI-2007 D. Brzoska ex. flight intercept trap PER1B07 004 / SEMC0874476 KUNHM-ENT’ (SEMC).

In addition to characters in the genus description, the species is characterized by the following primary and secondary male sexual characters. Sternite VIII without apical incision. Tergite X apparently fused to internal face of lateral sclerites (Fig. 5A, solid line), with two large setae situated at apical third of length (Fig. 5A; LS). Sternite IX emarginate apically, with symmetrical basal stem (Fig. 5A, dashed line). Lateral tergal sclerites and tergite X of approximately equal length. Aedeagus (Fig. 5B, C); paramere longer than and closely attached to, median lobe (Fig. 5B); lateral apical area of paramere with setae of varying length (Fig. 5C; ST); internal sac consisting of a pair of heavily sclerotized oblong-shaped sclerites (Fig. 5C; OS) and pair of weakly sclerotised longer, more slender sclerites extruding from apical area of median lobe under pressure (Fig. 5C, SS).

Figure 5. 

Morphology of Amazonothops aslaki gen. et sp. nov. A male terminalia (abdominal segments IX, X) B aedeagus in lateral view C aedeagus in antiparameral view (slightly lateral). LS, Long setae. OS, Oblong sclerite. SS, Slender sclerite. ST, setae.

Based on the specimens studied here, the new genus is restricted to the lowland areas of the Amazonian basin of Peru (Fig. 6). As a fully winged species known only from six specimens from two areas approximately 1000 kilometres apart from each other, it seems to be a widespread species, perhaps much more than it appears now.

Figure 6. 

Known distribution of Amazonothops aslaki gen. et sp. nov. in Peru.

Same as above.

The species is named in honour of Aslak Kappel Hansen (NHMD) who was one of the collectors of this new genus and who brought our attention to its unusual nature compared to Heterothops.

It is notable that a species of Heterothops (Amblyopinini) was obtained during the same collecting event as one of the Amazonothops specimens. This shows that these two similar looking, yet phylogenetically distant (Fig. 1) taxa co-occur, probably in similar or the same microhabitats in the Amazon basin.