Ersachus erichsonianus Sharp, 1902

Arce-Pérez, Roberto, Arriaga-Varela, Emmanuel, Cifuentes-Ruiz, Paulina & Escobar, Federico, 2014, Rediscovery of the GenusErsachusErichson in Veracruz, Mexico, with a Description of the Female ofErsachus erichsonianusSharp (Coleoptera: Byrrhoidea: Limnichidae), The Coleopterists Bulletin 68 (4), pp. 765-769 : 765-769

Ersachus erichsonianus Sharp, 1902 ( Figs. 1 – 10 )

Diagnosis. Ersachus erichsonianus is distinguished from the other Ersachus species known from Mexico and Central America because it lacks a densely punctate protuberance or gibbosity on the medial portion of the pronotum, which is present in E. mexicanus ; also, it has larger dimensions, 3 mm long by 1.5 mm wide, and a proportionally wider form, about two times longer than wide, while E. mexicanus is 2 mm long and 1.1 mm wide. From E. lugubris , it can be separated by its size ( E. lugubris is 2.5 mm long and 1 mm wide) and by its lighter colored integument ( E. lugubris is almost black in color).

Description. Female. Body ( Figs. 1 – 3 ) oval, 2.95 mm long, 1.45 mm wide at humeral region; integument dark brown, only antennae, palpi, and tarsi yellowish; covered by a short, fine vestiture; elytra with oval patches formed by light colored setae; ventral surface, legs, and antennae covered with short, silver-gray setae. Head ( Fig. 4 ): Opisthognathous, about as wide as the anterior part of pronotum, partially retracted in it; eyes large, circular, widely separated; antennae thin, inserted below the inferior margin of eyes, first 2 articles globose, markedly wider than the articles that follow; articles 3 – 6 narrow and subconical, last 5 articles forming a moderately compact club with apical article acuminate; labial palps short; maxillary palps with 4 articles, the first 3 articles short and subconical, apical article large, slightly globose, acuminate, ending in a small tip. Thorax: Pronotum trapezoidal, 0.58 mm long at midline, 1.16 mm wide at posterior margin; posterolateral angles markedly acute and projected; anterior margin rounded, posterior margin sinuate, with a slight medial emargination before scutellum that bears a small tooth on each side and a smaller one at the center. Surface of head and pronotum densely punctate, each puncture 1 diameter apart from the next; covered by fine, golden setae.

Scutellum triangular, equilateral, with golden setae. Ventral surface covered by short, silvergray setae. Prosternum wide ( Fig. 4 ); hypomeron flat, without excavation for reception of legs; prosternal process triangular, wide, elongate, weakly margined, without carinae or sulci, only slightly depressed near lanceolate apex. Mesoventrite narrow, with a deep, subhexagonal cavity for reception of prosternal process. Metaventrite wide and lightly convex, without sulci or carinae, slightly depressed in anterior margin. Elytra: Long, completely covering the abdomen; the humeral callus extremely prominent, forming a constriction of elytron; apex of each elytron acute; surface with punctures not arranged in striae, punctures larger and sparser than on pronotum, separated from each other by 3 – 4 diameters; covered with 2 types of decumbent setae ( Fig. 6 ), one dark brown, situated at the center of punctures, about 4 times longer than diameter of punctures, other smaller, wider at base, silvergray or golden, forming transverse series of patches arranged as follows: small, longitudinal, golden band at each side of scutellum, between suture and humeri, followed by a series of 4 oval, gray-silver patches, then a series of 2 larger golden patches, 4 gray patches, 2 larger golden patches, 4 gray patches, 2 golden patches, 4 smaller gray patches, and 1 gray patch near apex. Faint golden stripe along suture, absent in apical 1/4; elytron with epipleuron wide and complete ( Figs. 2, 3 ). Legs: Procoxae slightly globose and transverse; mesocoxae globose; metacoxae flattened and widely transverse; trochanters short; femora, tibiae, and tarsi thin, without teeth or spines; tarsi 5-segmented, 5 th tarsomere subtriangular, larger than any of those that precede, but shorter than tarsomeres 2 – 4 together. Abdomen: Subtriangular, with 5 visible sternites ( Fig. 5 ) without modifications; 2 nd sternite wider than others. Genitalia: Spiculum ventrale ( Figs. 8, 10 ) thin at base,Y-shaped, deeply emarginate apicomedially, with long setae at margin. Ovipositor ( Figs. 7, 9 ) long (1.44 mm), strongly sclerotized, gonocoxites long and acute.

Material Examined. MEXICO: Veracruz, Ixhuacán de los Reyes, Buenavista (19°24 ′ 12.6 ″ N, 97°05 ′ 16.1 ″ E), Fragment of Mountain Cloud Forest , 1788 masl., April 2012, Winkler extractor, Col F. Alvarado ( IEXA: ♀) .

Distribution. This species was previously known only from the localities cited in the original description ( Sharp 1902): Caldera in Panama, San Jerónimo in Guatemala, and Xalapa in Mexico. However, such records lack information about the date and method of collection and vegetation type at the sites. The present work is the first precise geographical record for the species. Our locality is in the mountain zone of Ixhuacán de los Reyes, Veracruz, about 23 km southwest of Xalapa, only the second known Mexican locality for the species.

Figures

Figs. 1–10. Ersachus erichsonianus. 1) Dorsal view; 2) Ventral view; 3) Lateral view; 4) Head and prosternum, ventral view; 5) Abdomen; 6) Surface of elytron; 7) Ovipositor; 8) Spiculum ventrale; 9) Ovipositor; 10) Spiculum ventrale.