Edrabius uruguayensis Martínez-Villar, González-Vainer & Tomasco, 2020

Martínez-Villar, Mauro, González-Vainer, Patricia & Tomasco, Ivanna H., 2020, A new species of Edrabius Fauvel (Coleoptera, Staphylinidae, Staphylininae) from Uruguay, Zootaxa 4819 (2), pp. 393-400 : 396-398

Edrabius uruguayensis Martínez-Villar, González-Vainer & Tomasco , sp. nov.

( Fig. 1 )

Diagnosis. Edrabius uruguayensis can be distinguished by the following combination of characters: head trapezoidal with posterior angles rounded to front; short antenna, article 11 with apical edge oblique; pronotum moderately transverse, integument with fine and weak microsculpture; elytra with thick black setae on the humeral angle and a bunch of long golden fine setae at the outer rear corner; hind coxa longer than broad, with prominent rounded external basal angle; apex of the middle lobe of the aedeagus quadrangular with straight anterior margin.

Description. Body average length 5.4–6.5mm. Coloration: uniformly light reddish-brown ( Fig. 1 ). Head: (HW= 1.15mm; HL= 0.69mm; HW/HL= 1.66) trapezoidal, with lateral margins narrowing uniformly from rounded posterior angles to front ( Fig. 2. A ); integument of head with fine punctation; micropunctures arranged in pairs that consist of two types of sensillae: campaniform and coeloconic ( Fig. 2. B ). Microsculpture barely apparent with fine, short and broken stripes that do not form a reticulum, more closely compacted towards the anterior and posterior margins ( Fig. 2. B ); 1–2 rows of microsetae directed forward near the posterior margin ( Fig. 2. A ). Antenna: as long as the head and half of the pronotum with 11 articles, 2 longer than 3, 4 10 trapezoidal, moniliform, 11 longer than 10 with oblique apical edge ( Figs. 2.A ; 3.A ). Pronotum: moderately transverse, wider than long (PW= 1.41mm; PL= 0.99mm; PW/PL= 1.42), with antero—lateral macroseta ( Figs. 2. A ; 3. B ); very small microsetae extend from the antero—lateral margins to about half of the lateral margin. Integument microsculpture similar to the head; fine and relatively sparse micropunctures that represent sensillae similar to those in the head ( Fig. 2. C ); golden pubescence over the antero—lateral margin and more abundant over the humeral angle to the anterior half of the lateral margin ( Fig. 3. B ). Elytra: (EW= 0.71mm; EL= 0.67mm; EW/EL= 1.05mm) with a dense covering of fine, golden short setae, with thick black setae in the humeral angle and with long golden setae on the external posterior angles; in addition with a long and golden macroseta close to antero-lateral margin; outer posterior angles well defined ( Fig. 2. A ); micropunctures coarser than the head and pronotum. Hind coxa longer than broad, with prominent rounded external basal angle ( Fig. 3. C ). Abdomen: dorsally uniformly covered with a golden fine pubescence; each tergite with two setae on each side of the posterior margin; long golden fine setae all along the posterior margin. Apices of the lateral plates of tergum IX with a distinctive cluster of extremely long and aciculate setae ( Fig. 3. D ). Aedeagus: as in Figs. 2 . D-F; apex of median lobe quadrangular in lateral view, with apical margin straight and upper and lower margins parallel; 8 short spurs along the bottom edge and 4 thick and longer spurs on the posterior margin ( Fig. 2.E ); 2 lateral macrosetae close to apical margin and two others in a row backwards. Surface of the apex with numerous basiconic sensillae, more concentrated towards the end. Internal sac with a prominent sclerotized tooth ( Figs. 2. F ). Length of median lobe about 1.45 mm.

Male tergite 8 trapezoidal, lateral margins straight in the anterior half and with slightly pronounced curvature in the posterior half; posterior margin shallowly and broadly emarginated; posterior half with two long hairs near the lateral margin (one each); sternite 8 with posterior margin strongly emarginated; width of emargination about 2.6 times depth ( Fig. 3. E, F ).

Female tergite 8 trapezoidal with apical margin straight; sternite 8 similar to tergite ( Fig. 3. G, H ).

Material examined: Holotype (male), Uruguay: Departamento Río Negro, Estancia El Tabaré (33° 21´36.4´´ S 58° 18´52.1´´ W), sobre Ctenomys rionegrensis , 15.III.2017, M. Martínez-Villar, I.H. Tomasco and N. Boullosa (label 4409) ( FCE). Four paratypes (1 male, 3 females): same data as holotype (labels 4410 ─ 4413) . Holotype and paratypes were deposited in the Entomological Collection of Facultad de Ciencias ( FCE), Universidad de la República (Montevideo, Uruguay) . Other material examined: 2 males and 2 females, same data as holotype, were prepared for the scanning electron microscopic photographs and then stored in FCE .

Distribution. Species known only from Estancia El Tabaré (33° 21´36.4´´S 58° 18´52.1´´W), Rio Negro Department, Uruguay.

Etymology. The specific name is derived from the country, where the type specimens were collected.

Biology. The adults of Edrabius uruguayensis were found living on the fur of Ctenomys rionegrensis .

Molecular analyses. We were able to sequence a fragment of 646 base pairs of the COI gen. We reported two haplotypes for the species, which form a monophyletic group. All phylogenetic reconstruction methods applied were concordant among them ( Fig. 4 ), and show the inclusion of Edrabius uruguayensis sp. nov. in the family Staphylinidae , and a closer relationship with the genus Heterothops , from the same tribe, and also confirm the monophyly of most genera included, except for Heterothops that seems to be polyphyletic. However, bootstrap values are low, and no strong conclusions can be hold.

Figures

FIGURE 1. Edrabius uruguayensis sp. nov. 1A. Male holotype habitus, dorsal view; 1B. Female habitus, dorsal view. Scale bar 1 mm.

FIGURE 2. Edrabius uruguayensis sp. nov. 2A. Dorsal view of the head, pronotum, elytra and antenna; 2B. Campaniform and coeloconic sensillae and microsculpture from the head; 2C. Campaniform and coeloconic sensillae and microsculpture from the pronotum; 2D. Aedeagus, lateral view; 2E. Apex of aedeagus, lateral view; 2F. Basiconic sensillae and spurs from the apex of aedeagus.

FIGURE 3. Edrabius uruguayensis sp. nov. 3A. Anntena; 3B. Pronotum; 3C. Hind Coxa; 3D. Lateral plates of the abdominal tergum IX; 3E. Eight male tergite; 3F. Eight male sternite; 3G. Eight female tergite; 3H. Eight female sternite. Scale bar 0.5 mm

FIGURE 4. COI phylogenetic reconstruction. Numbers under nodes correspond to the percentage of 5000 pseudoreplications of bootstrap for the different reconstruction methods, in this order: Parsimony, Maximum likelihood, Neighbor Joining respectively.