Eleodes (Eleodes) tribulus Thomas, 2005

Smith, Aaron D., Dornburg, Rebecca & Wheeler, Quentin D., 2014, Larvae of the genus Eleodes (Coleoptera, Tenebrionidae): matrix-based descriptions, cladistic analysis, and key to late instars, ZooKeys 415, pp. 217-268 : 234-235

Eleodes (Eleodes) tribulus Thomas, 2005 Figs 2D , 5B , 9D

Material examined.

Larval Eleodes tribulus specimens were reared from adults with the following collecting information: "USA: AZ: Pinal Co. / I-10W Rest Area, mm183 / 33.029288, -111.771716 / 02 May 2011, ADSmith". A total of 824 eggs and larvae were reared and examined for this study, of which 134 survived until the 2nd instar or later. The following description is based on a detailed examination of ten 8-11th instar specimens.

Description.

TL: 13.0-19.0 mm, HW: 1.5-2.2 mm, PL: 1.2-2.7 mm, PW: 1.3-2.7 mm.

Head. Prognathous or weakly declined; weakly dorsoventrally flattened; width nearly equal to prothorax; sides angular; strongly constricted before occipital foramen; color light tan to medium brown, more heavily pigmented than body segments; punctation minute, moderately dense, separated by 2-4 puncture diameters. Epicranial suture stem length approximately one-third head capsule length; frontal arms sinuate, not obscured by sculpturing. Frons rugose. Epicranial plates weakly rugose dorsally; lateral portions moderately setose; ventral portion of each plate with row of six or more long setae along anterior margin near buccal cavity confluent with setae on lateral portions of plates, and a patch of short setae medially, forming a triangular pattern with its base near the anterior margin. Two stemmata present on each epicranial plate, pigmented spots often faded. Clypeus trapezoidal, swollen, darker medially in basal half, minutely punctate, punctation moderately dense, separated by 2-4 puncture diameters. Labrum swollen, sides rounded, basal half more darkly pigmented, medial setal row with six to seven erect setae subapical setal row with six to seven erect setae, anterior margin straight to weakly emarginate. Epipharynx ( Fig. 9D ) anterior setal row with six stout spiniform setae, anterolateral margins with micro-setation; five to six anterior sensory papillae present, arranged in two irregular longitudinal rows or an irregular cluster; four subanterior sensory papillae present, arranged as a transverse row subtended by two spinose setae; seven to eight posterior sensory papillae present, arranged in an irregular cluster. Tormae asymmetric, left torma larger. Ligula apex and subapical dorsal surface densely micro-setose, two long subapical setae present ventrally. Hypopharyngeal sclerome pentagonal, tricuspidate. Gula distinct, trapezoidal, widest in basal half, length subequal or greater than maximum width. Antenna three segmented, cylindrical, first segment length subequal to second.

Thorax. Thoracic tergites light tan, prothoracic sternite anterior to legs medium brown, thoracic sternites posterior to prolegs light brown. Prothoracic tergum subquadrate, 1.5 × length of meso- or metaterga; lateral margins with distinct granulated band, darker than protergal disc; anterior transverse striated band present, darker than tergal disc. Posterior transverse striated band present on all thoracic tergites, unicolorous brown. Meso- and metathoracic tergites wider than long, each with a faintly indicated sclerotized transverse line present on anterior fifth. Thoracic tergites sparsely setose on dorsal surfaces, lateral margins more densely setose. Mesothoracic spiracle simple, ovate, approximately 1.5 × size of abdominal spiracles; reduced metathoracic spiracle visible, less than one-fourth size of mesothoracic spiracle. Legs. Prothoracic leg slightly longer, much thicker than meso- and metathoracic legs; prothoracic tarsungulus strongly sclerotized, sickle-shaped; prothoracic trochanter with two stout spines ventromedially; prothoracic femur with ventromedial row of two spines and three to five longer setae, dorsal surface with faintly indicated basal sclerotized band; prothoracic tibia with ventromedial row of three to four spines, dorsal surface slightly more sclerotized than ventral surface. Mesotibia with three ventromedial spines.

Abdomen. Abdominal tergites and sternites light tan with darker transverse striated bands present along posterior margins of segments I-VIII, forming near contiguous unicolorous band around segments. Abdominal sternite I moderately clothed in long erect setae from anterior margin to near midline. Abdominal laterotergites with lateral margins distinctly pigmented. Abdominal segment IX (pygidium) triangular in dorsal view, gradually reflexed to apex, urogomphi absent, apex not forming a distinct tooth, moderately clothed in short and mid length erect setae, sclerotized uniformly throughout, lacking maculations; marginal row of 8-14 socketed spines present, arranged as single row around posterior two-thirds to one half of segment. Abdominal sternites I-VIII lacking longitudinal tomentose bands along lateral margins. Pygopods short, subconical, each with 11-15 erect setae.

Diagnosis.

Eleodes tribulus larvae can be separated from the other currently known Eleodes species based on the pentagonal hypopharyngeal sclerome, lack of a caudal tooth on the pygidium, presence of 8-14 marginal spines on the pygidium, and the angular, nearly straight sides of the head capsule.

Figures

Figure 2. Dorsal habitus of four Eleodes species: A Eleodes (Caverneleodes) wheeleri; B Eleodes (Eleodes) armatus C Eleodes (Eleodes) caudiferus D Eleodes (Eleodes) tribulus. Scale bar = 5 mm.

Figure 5. Lateral habitus of three Eleodes species: A Eleodes (Eleodes) caudiferus B Eleodes (Eleodes) tribulus C Eleodes (Litheleodes) extricatus. Scale bar = 5 mm.

Figure 9. Epipharynges of four Eleodes species: A Eleodes (Melaneleodes) carbonarius B Eleodes (Eleodes) armatus C Eleodes (Eleodes) hispilabris D Eleodes (Eleodes) tribulus. Scale bars = 1 mm.