Thyreocephalus jalapaensis Bordoni, 2002

Márquez, Juan & Asiain, Julieta, 2016, Taxonomy of the Mexican species of Thyreocephalus Guérin-Méneville (Coleoptera: Staphylinidae, Xantholinini), Zootaxa 4169 (2), pp. 251-285 : 260-262

Thyreocephalus jalapaensis Bordoni, 2002

( Figs. 2 a, b, 5c, 6f, 9c, 11c, 12b)

Saurohypnus nigerrimus Sharp, 1887: 791

Thyreocephalus nigerrimus ; Smetana, 1982: 70 (name pre-occupied by Kraatz, 1859 in Xantholinus ) Thyreocephalus jalapaensis Bordoni, 2002: 248

Total body length 14.2–17.2 mm. Body black, except antennomeres 4–11, maxillary and labial palps, and tarsi reddish.

Head oval shaped, slightly wider posteriorly, 1.1 times longer than wide, 1.17 times wider than pronotum ( Fig. 2 a). Dorsal surface moderately convex in lateral view, glossy, with sparse umbilicate punctures and heterogeneously distributed, at middle level of eyes posteriorly is denser that anteriorly, front almost smooth, posterior half with the umbilicate punctures separated up to 4 times their width ( Fig. 2 a). Ventral surface almost plane, with sparse, deep and conspicuous umbilicate punctures, almost homogeneously distributed ( Fig. 2 b). Eye almost 0.25 times as long as head. First antennomere almost two times as long as second and third antennomeres combined, second shorter than third, antennomeres 4–10 slightly transverse. Labrum with three pairs of apical teeth, the central pair less acute than lateral pairs ( Fig. 5 c). Mandibles 0.56 times as long as head, left mandible with one large and one small tooth, right mandible with one large tooth. Neck with one sunken area formed by two lateral cavities interconnected by an anterior suture ( Fig. 2 a).

Pronotum 1.37 times as long as wide, 1.17 times wider at anterior corners than posterior corners. Lateral punctures with similar pattern as in remaining species ( Fig. 2 a). Scutellum with 6–8 fine punctures and microsculpture as wavy lines. Elytra almost as long as pronotum, with dense, large and conspicuous punctures homogeneously distributed, except for the smooth belt parallel to lateral border. Prosternal sclerite faintly divided by a longitudinal line. Prosternum with posteromedian carina poorly developed and acute intercoxal process ( Fig. 6 f). Mesosternum and metasternum as in remaining species.

Abdomen glossy, with microsculpture as wavy lines and covered by clear setae that are moderately dense. First four visible tergites with a transverse area slightly sunken parallel to the anterior border. Aedeagus small, length 1.0– 1.1 mm, longer-oval, wider at base; apical area of median lobe acutely conical, 0.28 times as long as median lobe; parameres symmetrical, homogeneously curved and acute toward apex, large (0.39 times as long as median lobe); internal sac few conspicuous, short, occupying almost 1/2 of the length of median lobe, microsculpture visible only at apex ( Figs. 9 c, 11c).

Variation. Most of the analyzed specimens have the elytra brown to dark brown, and 5 of 12 have both elytra and ventral surface of the body dark brown. Some variation of the density of umbilicate punctures on the head, in the developed of mandibular teeth and development of the posteromedian carina of the prosternum also was observed. The proportion length/width of the head varies from 1.06 to 1.15 times, and the proportion width of the head/width of pronotum from 1.11 to 1.28.

Diagnosis. Due to its black coloration, T. jalapaensis can be confused with T. unicolor and T. sp. aff. subtilis . In diagnosis of T. unicolor we commented how to distinguish it from T. jalapaensis . Thyreocephalus jalapaensis is easily distinguished from T. sp. aff. subtilis by the lack of metallic blue reflection on the elytra, a different density and distribution of the umbilicate punctures on the ventral surface of the head, the presence of three pairs of apical teeth on the labrum and a different aedeagus. Thyreocephalus sp. aff. subtilis has metallic blue reflections on the elytra, ventral surface of the head with dense umbilicate punctures at posterior corners combined with roughness, labrum with two pairs of apical teeth and aedeagus slightly longer, with internal sac visible.

Discussion. This is one of the two species occurring in the United States, together with T. arizonicus , that was transferred from Saurohypnus to Thyreocephalus and redescribed by Smetana (1982; as T. nigerrimus ). Bordoni (2002) noticed that the name Thyreocephalus nigerrimus was pre-occupied by Kraatz, 1859, and proposed the new name T. jalapaensis . There are no important problems for identification and the characters mentioned by Sharp (1887) and Smetana (1982) were observed in the examined specimens. In this work the most relevant characters are pointed out, the species are distinguished from other Mexican species, and their geographical distribution is extended.

Distribution ( Fig. 12 b). This species is recorded for Mexico (Hidalgo and Veracruz) and the United States of America (Texas) ( Table 2 ) ( Sharp 1887, Smetana 1982, Navarrete-Heredia et al. 2002, Márquez 2006).

Material examined. "Mexico: Hidalgo, Metztitlán, Reserva de la Biosfera Barranca de Metztitlán, Río Venados , N 20° 49´52", W 98° 40´17", 1452 m, matorral xerófilo con vegetación secundaria, en troncos caídos, 1- X-2002, J. Asiain y J. Márquez cols." (3♂, 2♀, CC-UAEH); same data as previous, except: " Pilas y Granadas, hojarasca cernida, 4-VI-2007 " (1♀, CC-UAEH); " Mexico : Hidalgo, Cardonal, Grutas de Tolantongo , matorral xerófilo y cultivos, ex plátano podrido, 6 a 17-VII-1994, J. Márquez col." (1♂, MZFC) ; "Mexico: Veracruz, Coatepec, La Pitaya , N 19° 29´28.6", W 96° 56´59.1", selva mediana subcaducifolia, 1246 m, en troncos, 24-XI- 1998, Q. Santiago col." (1♂, MZFC) ; "Mexico: Veracruz, Xalapa, La Herradura, bosque mesófilo de montaña, en troncos podridos, 21-II-1999, Q. Santiago y J. Márquez cols." (1♀, MZFC) ; "Mexico: Veracruz, Xalapa , Rancho Guadalupe, 1460 m, trampa de plátano, VI-1999, R. Arce col." (1♀, CZUG) ; " Veracruz, municipio Xalapa, Xalapa, Colonia Zapata , N 19° 30´32", W 96° 55´10", 1360 m, en suelo, P. Carrillo-Reyes leg., V-2005." (1♀, CZUG) ; " Veracruz, Xico, Cascadas de Texolo (Teocelo), bosque mesófilo de montaña, bajo rocas, 5-IV-1996, J. Márquez col." (1♀, MZFC) .

Figures

FIGURE 2. Thyreocephalus jalapaensis: a) dorsal view of the head and pronotum; b) ventral view of the head (mandibles excluded). Thyreocephalus scutellaris: c) dorsal view of the head and pronotum; d) ventral view of the head (mandibles excluded). Thyreocephalus cribripennis: e) dorsal view of the head and pronotum; f) ventral view of the head (mandibles excluded). Scale = 2 mm.

FIGURE 5. Dorsal view of the labrum of: a) Thyreocephalus unicolor, b) T. sp. aff. subtilis, c) T. jalapaensis, d) T. scutellaris, e) T. puncticeps, g) T. rufipennis, h) T. halffteri, i) T. arizonicus.

FIGURE 6. Ventral view of the pronotum showing the posteromedian carina (lacking in b) and the postcoxal process in: a) Thyreocephalus puncticeps, b) T. sp. aff. subtilis. Lateral view of the pronotum showing the develop and variation of the posteromedian carina in: c) T. puncticeps, d) T. arizonicus, e) T. scutellaris, f) T. jalapaensis, g) T. unicolor.

FIGURE 9. Ventral view of the aedeagus of: a) Thyreocephalus unicolor, b) T. sp. aff. subtilis, c) T. jalapaensis, d) T. scutellaris, e) T. cribripennis, f) T. rufipennis, g) T. halffteri. Scale = 0.5 mm.

FIGURE 12. Geographic distribution and individual track of: a) T. puncticeps (black squares) and T. unicolor (black circles); b) T. arizonicus (gray squares), T. jalapaensis (black circles) and T. rufipennis (white circles).