Taxonomy of the Mexican species of Belonuchus Nordmann (Coleoptera: Staphylinidae) Author Márquez, Juan 0000-0001-5423-3545 marquezorum@gmail.com Author Asiain, Julieta 0000-0002-7958-4779 asiainae@yahoo.com text Zootaxa 2022 2022-06-10 5152 1 1 129 http://zoobank.org/92e9dd85-6cc6-4602-bd7c-c51f49ceef47 journal article 10.11646/zootaxa.5152.1.1 1175-5326 6630873 92E9DD85-6CC6-4602-BD7C-C51F49CEEF47 Belonuchus erichsoni Bernhauer, 1917 Figs. 4g , 17m , 19e, 23b, 27a Belonuchus erichsoni Bernhauer, 1917: 223 . Total body length in males 12.3 mm (range 11.4–13.7 mm ), in females 12.6 mm (range 11.3–13.8). Black on head, antennae, base of mandibles, pronotum, scutellum, prosternum, anterior half of mesoventrite, sixth visible abdominal segment (except its anterior border), genital segment and abdominal styli. Reddish on elytra, posterior half of mesoventrite, metaventrite, legs, and from first visible abdominal segment to anterior border of sixth. Head : transverse, ratio length/width in males 0.79 (range 0.71–0.86), in females 0.86 (range 0.80–0.89); convex at posterior corners. Dorsal surface with sulcate longitudinal midline visible in anterior half of head; front rounded foveate slightly backward of level of antennal insertions. Eyes slightly shorter than 0.5 times the cephalic lateral length, not protruding at sides. Antennomeres 2–3 almost equal in length, 4–6 elongate, 7 as long as wide, 8–10 transverse. Males with mandibles 1.23 times longer than head (range 1.03–1.50), in females almost as long as head (0.975 times, range 0.92–1.03); each with two small, moderately separated teeth (basal and middle); mandibular channel slightly developed, with external margin not carinate, internal margin like impressed line extending beyond level of middle tooth. Ventral surface lacking puncture at external anterior quarter, only with very fine and sparse punctures. Males with head 1.13 times wider than pronotum (range 1.03–1.22), in females 1.07 (range 1.03–1.12). Neck in ventral view with microsculpture a little coarser than on head. Thorax : each dorsal row of pronotum with six or seven punctures, less frequently five punctures; males with pronotum 1.14 times longer than wide (range 1.10–1.20), in females 1.2 (range 1.16–1.25); in both sexes almost as wide at anterior corners than at posterior corners (ratio in males 1.08, range 1.03–1.12, in females 1.06, range 1.03–1.07). Scutellum and elytra with fine punctures moderately dense. Prosternum slightly elevated behind posterior margin. Intercoxal process of mesoventrite shield-shaped; transverse discal ridge well developed, broadly Ushaped, not touching margin of intercoxal process laterally. Profemur of males somewhat widened toward anterior portion, but near apex is narrowed by means of a curvature, although not forming an apical notch as clear as in B. bidens ; external row of spines well developed from base to before narrow part; internal row with very small spines that are increasing in size toward apex, where some of them are longer than spines of external side. Metafemur of males with two rows of spines not well aligned at base, where there are additional spines, but well aligned distad; reaching slightly more than 1/2 of length of posterior femur; spines of external side are longer and wider than spines of internal side, and comparatively bigger than spines of B. rufipennis . Metatibiae straight. Tarsomeres moderately flattened dorsally. Abdomen : first three visible tergites with posterior basal transverse carina well developed, fourth visible tergite with posterior basal transverse carina as indistinct line on sides and absent at center; adjacent area of first three visible tergites narrow and slightly depressed, with wide-superficial punctures moderately dense that disappear backwards; additionally, entire surface of each tergite with fine, sparse punctures; punctures on tergite four similar to that of anterior tergites, tergites 5–6 only with fine puctures. Sternites with density and type of punctures similar to that on tergites. Male pregenital sternite strongly emarginate at posterior margin, emargination U-shaped or V-shaped, as deep as 1/5 to 1/4 of total length of sternite (Fig. 17m ). Male genital sternite short (2.29 times longer than wide), moderately asymmetrical, anterior portion occupying 39% and posterior portion 61% of its length, apical emargination very deep ( Fig. 19e ). Abdominal styli slender, with apex slightly rounded. Aedeagus : length 1.95 mm ; oval-elongate shape, with apex slightly acute and narrowed apicad, with a circular line at base of median lobe; basal half moderately wider than apical half; internal sac conspicuous ( Fig. 23b ). Variability . In addition to the variation in measurements and ratio included in the description, and variation due to sex and size of specimens, frequent variation was observed in the number of punctures in each dorsal row of pronotum: 5:6, 6:5, 7:6, 6:7; the punctures on scutellum may be slightly denser than on elytra; sixth visible abdominal segment may present an irregular border between black and reddish color, but the proportion is always close to basal 3/4 black and apical 1/4 reddish. Taxonomic comments . This species can be confused with B. mixtecus , B. pollens and B. rufipennis , due to its similar coloration pattern and the presence of two rows of spines on the male posterior femora. It is distinguished from B. pollens and B. rufipennis by having 6–7 punctures in at least one dorsal row of pronotum and abdomen with only the sixth visible segment black (with the anterior border reddish); while the two previous species have five punctures in each dorsal row of pronotum and part of the fifth visible abdominal segment and entire sixth black. With B. mixtecus it shares having six or seven punctures in at least one dorsal row of pronotum, male pregenital sternite deeply emarginate at posterior margin, and shape and size of genital sternite and aedeagus, although the latter two characters are quite similar but not identical in these species. They can be distinguished because B. erichsoni has the sixth visible abdominal segment black (with the anterior border reddish), metafemora of males not flattened in basal half of external surface, metatibiae of males straight, fourth visible abdominal tergite with posterior basal transverse carina as indistinct line laterally and absent medially, and because its aedeagus is of oval-elongate shape, with the median lobe evenly converging to apex. While in B. mixtecus , most of fifth and entire sixth visible abdominal segments are black, metafemora of males are somewhat widened and flattened in basal half of external surface, metatibiae of males are faintly curved at half length, fourth visible abdominal tergite does not have the posterior basal transverse carina, and its aedeagus is oval-shaped, more widened and with the median lobe parallel-sided for most of its length. The holotype was studied and compared with non-type specimens earlier, but was not available when the detailed descriptions of the species were made, so this redescription is based on non-type specimens. Type material examined: Holotype (male, FMNH ): “ Mexiko , Bang Haas / erichsoni Brh. , Mexiko , Type , Det. Bernhauer / Bernh., Type unic / Chicago NHMus, M. Bernhauer Collection / Belonuchus erichsoni Bernhauer ” . Additional material examined ( 23 males , 23 females ): Mexico : Estado de México : “ Otumba , Belem , N19°37´47” , W98°48´7” , en cultivo de nopales, trampa cebada con nopales fermentados, 20-VIII a 4-IX-2017 , A. Hernández y A. Rojas cols.” (26, CC-UAEH ) . Hidalgo: “ Acatlán , Loma Larga , El Llano , cultivos, matorral xerófilo y encinos, 2097 m , N20°16’13” , W98°28’18” , NTP-80 (calamar) 13 al 20-VII-2010 , J. Márquez y J. Asiain cols.” (2, CC- UAEH ). “ Huasca de Ocampo , Sta. María Regla, a los rededores del rio, cultivos y Juniperus , en nopales podridos, 27-VIII-2014 , J. Márquez col.” (2, CC-UAEH ). “ Santiago de Anaya , El Encinal, N20°26’56.0” , W98°55’ 20.5” , matorral xerófilo y encinos, trampa cebada con nopales fermentados, 22 a 29-VII-2018 , F.M. Gómez e I.S. Hernández cols.” (1, CC-UAEH ). “Zempoala, Sierra de Pitos , cerca de Mina San Juan Tepemazalco, bosque de encino, 2680 m , N19°54’ , W98°43’ , en nopales podridos, 10-IX-2002 , J. Márquez col.” (1, CC-UAEH ). “Zempoala, La Trinidad , matorral xerófilo, 2451 m , N19°57’75.9”, W98°43’58.7” , NTP-80 (carne de cerdo), 4 al 18- VIII-2004 , T14, G. Pajas y J. Márquez cols.” (2, CC-UAEH ). Same data, except: “4 al 25-VIII-2004 , T9” (2, CC-UAEH ). “Zimapán, P. N. Los Mármoles , Trancas, bosque de pino-encino, 2444 m , N20°48’12.22” , W99°14’41” , en nopal podrido, 18-IX-2007 , J. Márquez , J. Asiain y S. Sierra cols.” (2, CC-UAEH ). Same data, except: “coprotrampa, 12- VII a 17-VIII-2007 , J. Asiain , S. Sierra y J. Márquez cols.” (2, CC-UAEH ). Same data, except: “NTP-80, 22-VII a 17-VIII-2007 ” (1, CC-UAEH ). Same data, except: “ 17-VIII a 19-IX-2007 ” (1, CC-UAEH ). Same data, except: “NTP-80, 13-X a 17-XI-2007 ” (1, CC-UAEH ). Same data, except: “nopal podrido, 18-IX-2007 ” (1, CC-UAEH ). Querétaro: “Ezequiel, Montes, Bernal, El Descanso, matorral xerófilo, 2100 m , 5-III-1999 , en nopales podridos, S. Arenas y J. Márquez cols.” (1, MAAS ). Same data, except: “ 3-III-1999 , J. Márquez col.” (1, MAAS ) .