Megarthrus cavianae Rodríguez, Navarrete-Heredia & Arriaga-Varela, 2020

Rodríguez, William David, Navarrete-Heredia, José L., Arriaga-Varela, Emmanuel & Cuccodoro, Giulio, 2020, Two new species of Megarthrus (Coleoptera, Staphylinidae, Proteininae) from Mexican Cloud Forests, Zootaxa 4778 (3), pp. 571-583 : 578-581

Megarthrus cavianae Rodríguez, Navarrete-Heredia & Arriaga-Varela sp. nov.

( Figs 27-39 )

http://zoobank.org:act: F4814244-2EA7-493D-8086-01CC754585C0

Type material. (3♂, 2♀). Holotype ♂: labeled “ MÉXICO: Veracruz, San Andrés Tlalnelhuayocan, Piedra Parada, 19°30’58.6’’N 97°00’34.4’’W, 1522 msnm, Fragmento de Bosque Mesófilo de Montaña ripario, Cernido de Hojarasca húmeda, extraída en Winkler , 5.V.2013, F. Alvarado, E. Arriaga, R. Chavero cols”, in CZUG . Paratypes (4): labeled “ MÉXICO: Veracruz, Xico, Matlalapa, 19°26’24.8»N 97°02’37.2»W, 1532 msnm. Fragmento de Bosque Mesófilo de Montaña ripario, Cernido de Hojarasca húmeda, extraída en embudo de Berlesse , 20.VI.2012. F. Escobar, F. Alvarado, R. Chavero cols” , 1♀ in CZUG , 1♂ in IEXA , and 1 ♂, 1♀ in MHNG.

Description. Similar to M. chiapas from which it differs as follows: Habitus as in Fig. 29 . Combined length of pronotum and elytra = 1.0 - 1.4 mm; maximal pronotal width = 0.7 - 1.1 mm. Antennae as in Fig. 36 . Elytra with humeral callus strongly convex; disc with humeral callus strongly convex, two conspicuous swellings similar to humeral callus along anterior and posterior portions of suture, moderately depressed posteriorly along lateral edge. Male: Frontoclypeal area not modified. Protarsomere 1 lacking ventral patch of modified adhesive setae. Mesofemora ( Fig. 33 ) as long as metafemora. Mesotibiae ( Fig. 34 ) shorter than metatibiae ( Fig. 35 ), the latter slightly compressed subapically. Peg-like setae present only on mesotrochanters ( Fig. 33 ; arranged in a single row), on distal two thirds of mesotibiae ( Fig. 34 ; grouped in a field) and on distal half of metatibiae ( Fig. 35 ; grouped in a field). Apical segments of abdomen similar to those in Figs 10-15 & 18 ; tergite VIII as in Figs 38 , with apex sinuate in dorsal view. Aedeagus as in Figs 32 & 37 , with dorsal valve triangular.

Female: Abdominal tergite forming a medioapical projection, with dorsal outline subangulate subapically in lateral view VIII ( Fig. 31 ). Sternite VIII as in Fig. 30 . Genital segments similar to those in Figs 19-21 ; gonocoxal plate without mediodorsal ridge.

Comparisons and diagnostic notes. Megarthrus cavianae Rodríguez, Navarrete-Heredia & Arriaga-Varela sp. nov. is similar to M. chiapas Cuccodoro sp. nov., from which it differs by its more pronounced elytral relief, as well as several other features detailed in Comparisons and diagnostic notes under M. chiapas .

Distribution and natural history. Megarthrus cavianae Rodríguez, Navarrete-Heredia & Arriaga-Varela sp. nov. is apparently restricted to Mountain Cloud Forests in the south of the Transmexican Volcanic Belt ( Fig. 39 ). The specimens were collected from sifted leaf litter in riparian remnants of cloud forests at an elevation of approximately 1500 m.

Etymology. The specific name is a composite word in honor to Carmen Moreno Jiménez, Virginia de Jesús Rodríguez, Ana Cricelia Rodríguez, and Ana María Jiménez, in recognition of their unconditional support of the first author.

Figures

FIGURE 39. Distribution map of Megarthrus alatorreorum (diamond), M. altivagans (star), M. cavianae sp. nov. (square), M. chiapas sp. nov. (triangle), M. flavosignatus (pentagon) and M. zunilensis (circle).

FIGURES 25–28. Megarthrus chiapas sp. nov. (25, 26): prothorax in dorsal (25) and ventral (26) views, HR = hypomeral ridge. Megarthrus cavianae sp. nov., type locality (27–28): riparian remnants of mountain cloud forest in the Transmexican Volcanic Belt of Xalapa, Veracruz (27); sifted leaf litter in riparian remnants of cloud forests west of Xalapa, Veracruz (28). Scale bar = 0.2 mm: 25–26.

FIGURES 29–31. Megarthrus cavianae sp. nov., female: habitus in dorsal view (29); abdominal sternite VIII in ventral views (30); apical segments of abdomen in lateral view (31). Scale bars; vertical = 0.5 mm (29); 25–26. horizontal = 0.2 mm (30, 31).

FIGURES 32–38. Megarthrus cavianae sp. nov., male: aedeagus in ventral (32) and lateral (37) views; mesofemur and mes- otrochanter (33); mesotibia (34); metatibia (35); antenna (36); abdominal tergite VIII in dorsal view (38). Scale bars = 0.2 mm: 32–35, 37, 38 (horizontal); 36 (vertical).

FIGURES 10–18. Megarthrus chiapas sp. nov., male: apical segments of abdomen in ventral (10) and lateral (11) views; ab- dominal segments IX and X in lateral (12) and ventral (13) views; abdominal sternite VIII (14), sternite IX (15) and hemitergite IX (18) in ventral view; abdominal tergite VIII in lateral (16) and dorsal (17) views. Scale bars = 0.2 mm: 10–11 (vertical); 12–18 (horizontal).

FIGURES 19–24. Megarthrus chiapas sp. nov., female: genitalia in dorsal (19), posterior (20) and lateral (21) views; abdomi- nal sternite VIII (22) in ventral view; abdominal sternite VIII in lateral (23) and ventral (23) views. Scale bar = 0.2 mm.