Megarthrus wayqecha Pérez, Rodríguez & Asenjo, 2020

Pérez, Luis, Rodríguez, Maryzender & Asenjo, Angélico, 2020, A new Peruvian species of Megarthrus Curtis (Coleoptera: Staphylinidae Proteininae), Zootaxa 4731 (4), pp. 581-588 : 583-587

Megarthrus wayqecha Pérez, Rodríguez & Asenjo , sp. nov.

( Figs. 1–21 )

urn:lsid:zoobank.org:act:D381BA9B-848E-4D9B-B125-37EE635F93D4

Type material (43♂♂, 51♀♀). Holotype: PERU : ♂, labeled “PERU: CU[Department of Cuzco], Kosñipata, / Wayqecha , Trocha / Canopy , 13°11’32.8’’S, / 71°35’16.0’’W, 2931 m,” “ 02.xi.2017, cloud forest, / sifting of leaf litter, M. / Rodríguez & L. Pérez leg.” “ HOLOTYPE [red label] / Megarthrus wayqecha / sp. nov. / Desig. Pérez et al., 2019” ( MUSM) . Paratypes (94): 32♂♂, 33♀♀ labeled with the same data as holotype (21♂♂, 28♀♀ MUSM; 2♂♂, 1♀ MEKRB; 1♂, 1♀ CEMT; 2♂♂, 1♀ FMNH; 2♂♂, 1♀ MHNG; 1♂, 1♀ VMDC; 2♂♂, MPEG; 1 ♂, IADIZA) . 3 ♂♂ labeled as holotype with additional green label “DNA BARCODING / VOUCHER / BOLD Sys- tems / CCDB-30362-B01 to B03” ( MUSM) . 2♂♂, 6♀♀ labeled “PERU: CU[Department of Cuzco], Kosñipata, / Wayqecha Research / Center , 13°10’29.07’’S,” “ 71°35’11.98’’W, 2950 m, / 23.x.2017, cloud forest, /sifting of leaf litter, M. / Rodríguez & L. Pérez leg.” ( MUSM) . “ Peru: Cuzco Dept. /, Pillahuata. Manu rd, / km 126, 24.IX.1982, / FMND #82-2861, ex” “vine litter & fungus / nr. seepage area, / L. E. Watrous and G. / Mazurek ”(2 ♀♀ FMNH) ; same data but “km 128, 17.IX.1982, FMND #82-249, ex litter & seepage area” (1 ♀ FMNH) ; same data but “ 19. IX.1982, FMND #82-262, ex litter nr. falls” (1 ♂, 1♀ FMNH) ; same data but “ 23.IX.1982, FMND #82-281, ex litter & fungus nr. seepage area” (2 ♀♀ FMNH) ; same data but “ 25.IX.1982, FMND #82-293, ex litter, some nr. stream” (1♂, 2 ♀♀ FMNH; 2 ♂♂ MHNG) ; same data but “ 26.IX.1982, FMND #82-299, ex litter along stream” (1 ♂, 2 ♀♀ FMNH, 2 ♀♀ MHNG) ; same data but “ 27.IX.1982, FMND #82-307, ex leaf litter”(1 ♂ FMNH) . All paratypes labeled “ PARATYPE [yellow label] / Megarthrus wayqecha / sp. nov. / Desig. Pérez et al., 2019” .

Diagnosis. Among the members of the genus possessing the eleventh antennomeres piriform, Megarthrus wayqecha sp. nov. uniquely shares with the Argentinian M. ogloblini Bruch, 1940 (Fig. 147: Cuccodoro 2011) and the Colombian M. andinus López-García et al., 2011 the pronotum shallowly notched laterobasally with the lateral outline forming 4 distinct angles. However M. andinus is readily distinguished from these species by its conspicuous anterior adsutural elytral humps, and M. ogloblini has the male metatibiae cylindrical bearing peg-like setae on apical half, while males of M. wayqecha have the metatibiae enlarged and notched with peg-like setae grouped subapically. The shape of the aedeagus of M. wayqecha is also diagnostic: the median lobe in lateral view has the ventral face subapically straight with the tip of apex acute ( Fig. 18 ) and the dorsal valve (seen in dorsal view) is Vshaped ( Fig. 19 ).

Description. Holotype male (BL=3.11, BW=1.18, PL+EL=1.82). Body dark brown with appendages and legs somewhat paler, antennomeres 9–11 paler than antennomeres 1–8 ( Fig. 1 ). Dorsal pubescence of body fairly uniform, frontal setae directed forward, median area of frons less dense than on vertex; pronotum, elytra and abdomen with setae directed backward, denser on pronotum than on elytra, pronotal setae curved and recumbent, denser on pronotal disc; elytral setae curved and recumbent, becoming denser near humeral area with interspaces as wide as puncture diameters; metaventral pubescence uniform, with small protuberance near posterior margin; pubescence on abdominal tergites parallel, uniform. Frons with granulation conspicuous, with granulae about as high as their diameter or higher; pronotum and elytra granulofossulate, with granulation small.

Head ( Fig. 3 ) wider than long (HW=0.71, HL=0.53), mesal portion of disc strongly convex in lateral view; Ushaped frontal impression shallow; eyes medium size on posterior half; clypeus carinate, nearly rounded; temples convex in dorsal view. Antenna ( Fig. 2 ) symmetrical and filiform, 2.1 times longer than pronotum, antennomeres 1–4 without pubescence, antennomeres 5–11 pubescent; antennomere 11 piriform.

Pronotum wider than long (PW=1.27, PL=0.65), 1.2 times longer than head, anterior margin slightly concave and posterior margin slightly convex and bilobed in the middle ( Fig. 4 ). Pronotum with disc strongly convex and deeply depressed near middle of lateral edges, lateral and posterior edges shallowly depressed along disc. Anterior angles projected forward, lateral contours forming four denticles, posterior angles weakly projected backwards. Medial groove punctate and flat, slightly narrower in middle ( Fig. 4 ). Hypomeron with inner edge wider in its median portion, ridged from anterior margin to laterobasal angle, without a discal pit. Proventral medial ridge absent.

Scutellum triangular with anterior border rounded and posterior border slightly acute, margins slightly raised and with pubescence directed backward. Elytra wider than long (EL=0.96, EW=1.30), 1.8 times longer than pronotum, gradually widened toward apex ( Fig. 2 ), humeral callus raised, moderately convex; disc with low swellings, moderately depressed posteriorly and along lateral external edge, the latter finely carinate, slightly arcuate in dorsal view. Protrochanter without transverse ridge, small, subtriangular with one macroseta near the apex; profemur oblong with base flattened; protibia thin and shorter than profemur, inner face with many setae in the apical two thirds; protarsomere 1–4 dorsoventrally setose, protarsomere 1 as long as protarsomere 2–3 combined, protarsomere 5 with scarce setae, longer than protarsomere 1. Mesotrochanter subtriangular with peg-like setae arranged in two rows, one row with 7–8 peg-like setae and the second with 4–5 peg-like setae, and bearing one subapical macroseta ( Fig. 5 ); mesofemur oblong; mesotibia sinuate, shorter than mesofemur, with peg-like setae arranged in two rows, a row along 4/5 apical length and a short row from base to middle, and some apical peg-like setae not aligned ( Fig. 6 ); mesotarsomeres similar to protarsomeres. Metatrochanter subtriangular, incrassate ( Fig. 7 ); metafemur strongly very robust about twice as long as broad (0.71/0.30) ( Fig. 7 ); metatibia gradually enlarged toward apex, shorter than metafemur, with notched at subapical quarter constriction, and with peg-like setae grouped on apical quarter ( Fig. 7 ); metatarsomeres similar to protarsomeres.

Tergites III–VII pubescent with one pair of paratergites; tergites II–III covered by elytra, tergite IV partially covered. Medial process of sternite II shorter and smaller than medial process of sternite III ( Fig. 11 ). Sternite III– VII rectangular with pubescence. Tergite VIII triangular with anterior angles slightly projected forward, posterior margin forming an obtuse angle ( Fig. 8 ), with small and broad medial apical projection convex in lateral view ( Fig. 9 ). Sternite VIII trapezoidal, with lateral margin slightly convex, posterior margin strongly concave and membranous with four short macrosetae, anterior margin characteristic, inner plate asymmetrical with apex acute exceeding a little the anterior margin of sternite VIII ( Fig. 10 ). Hemitergites IX slightly asymmetrical, left hemitergite slightly bigger in ventral view, anterior margin of right hemitergite more concave than left ( Fig. 12 ). Sternite IX asymmetrical, oblong and thin ( Fig. 12 ).

Aedeagus as in Figs. 13–14 (internal sac evaginated), with median lobe oval-shaped in ventral view ( Fig. 13 ), in lateral view with ventral face subapically straight with the tip of apex acute ( Fig. 14 ), dorsal valve V-shaped.

Female. Similar to male, except mesotrochanter without peg-like setae; mesotibia without peg-like; metafemur thin; metatibia without peg-like setae; tergite VIII in lateral view with little and thin medioapical projection convex; sternite VIII without inner plate and posterior margin almost straight; genital segments as in Figs. 15–16 ; gonocoxal plate lacking mediodorsal ridge.

Remarks. The new species M. wayqecha sp. nov. is included in the definition of Megarthrus inaequalis - supergroup proposed by Cuccodoro (2011a) based on the following characters: presence of a long prohypomeral ridge extended posteriorly to the laterobasal angle, frontal pubescence directed forward ( Figs. 1, 3 ), antennomere 11 piriform ( Figs. 1, 2 ), and lack of adventral adhesive setae on the first male protarsomere. Within this supergroup only M. wayqecha , M. andinus and the Costa Rican M. mammiger Bierig, 1940 , lack a mediodorsal ridge on the female gonocoxal plate. However, M. mammiger has the pronotum conspicuously notched laterobasally, while it is only slightly notched laterobasally in M. wayqecha and M. andinus . Megarthrus wayqecha differs notably from M. andinus by its elytra lacking conspicuous antebasal adsutural humps. The sexually dimorphic features on the male legs, the shape of the aedeagal ventral wall, and the conformation of the female valvifers are also diagnostic.

Aedeagus with the internal sac not evaginated from a paratype as in Figs. 17–19 .

Three male paratypes and 16 female paratypes have the antennomere 9 yellow in apical half and brown in basal half.

Distribution and natural history. The specimens fron wayquecha were collected in a cloud forest between 2931 m and 2950 m, from the biological station “Wayqecha”, a private area recently protected by Peruvian law with the aim to preserve the biodiversity of Peruvian Yungas (MINAM, 2016) ( Figs. 20, 21 ). Wayqecha is placed 19 km SW of Pillahuata (13°08’S, 71°25’W), the type locality of M. machu Cuccodoro, 2001 . According to the information provided by the collector, the specimens were found in leaf litter with moss, ferns, and bamboo leaves alongside the roots and trunks of trees as observed in Fig. 21 .

Etymology. The specific name “Wayqecha” refers to the locality of collection of this new species. Wayqecha means ‘little brother’ in Quechua language. This is a noun in apposition.

Barcoding. The mitochondrial DNA sequences (COI) of three paratypes were identical ( Table 1 ). One COI sequence is as follows:

Figures

FIGURES 1–7. Megarthrus wayqecha sp. nov., male holotype from Wayqecha, Trocha Canopy (2, 4–6). 2, antenna; 4, pronotum; 5, mesotrochanter and mesofemur; 6, mesotibia. Megarthrus wayqecha sp. nov., male paratype from Wayqecha, Trocha Canopy (1, 3, 7). 1, habitus, dorsal view; 3, head, dorsal view; 7, metaleg with peg-like setae in the apex of metatibia.

FIGURES 8–16. Megarthrus wayqecha sp. nov., holotype (8–14). 8, tergite VIII, dorsal view; 9, tergite VII, tergite VIII, sternite VIII, lateral view, 10, sternite VIII; 11, medial area of abdominal sternites II–III in lateral view; 12, hemitergites IX and sternite IX; 13, aedeagus, ventral view; 14, aedeagus, lateral view. Megarthrus wayqecha sp. nov., female paratype, from Wayqecha, Trocha Canopy 15, genital segments, dorsal view; 16, genital segments, lateral view.

FIGURES 17–19. Megarthrus wayqecha sp. nov., male paratype. 17, aedeagus, ventral view (the side of the basal foramen); 18, aedeagus, lateral view; 19, aedeagus, dorsal view.

FIGURES 20–21. Habitat of Megarthrus wayqecha sp. nov. 20, panoramic view of the cloud forests of the Kosñipata valley, where the biological station Wayqecha is located. 21, sifting leaf litter on Trocha Canopy from the biological station Wayqecha.