Eleodes (Melaneleodes) anthracinus Blaisdell, 1909

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 : 237-240

Eleodes (Melaneleodes) anthracinus Blaisdell, 1909 Figs 3B , 6A , 7A , 8

Material examined.

Larval Eleodes anthracinus specimens were reared from adults with the following collecting information: "USA: AZ: Maricopa Co. / Eugie Ave & 7th St. / 25 Oct. 2011, R. Dornburg." A total of 28 eggs and larvae were reared and examined for this study, of which all survived until the 3rd instar or later. The following description is based on a detailed examination of four 8-11th instar specimens.

Description.

TL: 23.8-28.1 mm, HW: 2.3-2.4 mm, PL: 2.0-2.4 mm, PW: 2.5-2.8 mm.

Head. Prognathous or weakly declined; weakly dorsoventrally flattened; width nearly equal to prothorax; sides rounded; strongly constricted before occipital fo ramen; color medium brown to brown-grey, nearly as on body segments; minute punctation moderately dense dorsally. Epicranial stem approximately one-third head capsule length; frontal arms U-shaped, not obscured by sculpturing. Frons and dorsal portion of epicranial plates faintly rugose; lacking non-primary setae. Lateral portions of epicranial plates moderately setose; setae golden, erect, length equal to or longer than antennal segment 2; ventral portions of epicranial plates with a row of four long setae along anterior margin near buccal cavity with a patch of short setae medially forming a triangular pattern with its base near the anterior margin; two stemmata present on each plate, pigmented spots often faded. Clypeus trapezoidal; not swollen, moderately punctate, darker medially in basal half. Labrum not swollen, basal half more darkly pigmented; sides rounded; two transverse rows of seven to eight erect setae present medially and subapically; anterior margin straight. Epipharynx ( Fig. 3 ) anterior setal row with six stout spiniform setae, anterolateral margins with micro-setation; six anterior sensory papillae present, arranged in two irregular diagonal rows; four subanterior sensory papillae present, arranged as a transverse row subtended by two spinose setae; eight posterior sensory papillae present, arranged in two irregular rows.Tormae asymmetrical, left torma smaller. Ligula with four long setae near apex. Hypopharyngeal sclerome trapezoidal. Gula distinct, trapezoidal, widest in basal half. Antenna three segmented, cylindrical; first segment longer than second.

Thorax. Grey-brown to medium brown dorsally and anterior to legs on prothoracic sternite, tan on rest of sternites; lighter transverse striated band present along anterior fourth of prothoracic tergum; thin darkly sclerotized transverse line present on anterior fifth of meso- and metathoracic tergites; striated bands present along posterior 5th of all thoracic tergites, color forming a gradient from darker brown anteriorly to lighter brown along posterior border. Eight evenly arranged setae present on dorsal surface of each thoracic terga, lateral margins more densely setose. Prothoracic tergum subquadrate, 1.5 × length of meso- or metaterga; lateral margins lacking pigmented band. Meso- and metaterga wider than long, lacking pigmented bands along lateral margins; mesothoracic spiracle simple, ovate, approximately 1.5 × size of abdominal spiracle; reduced metathoracic spiracle visible, less than one-fourth size of mesothoracic spiracle. Prothoracic leg slightly longer, much thicker than meso- and metathoracic legs; prothoracic tarsungulus strongly sclerotized, sickle-shaped; trochanter with row of two stout spines and two longer setae ventromedially, tibia with ventromedial row of two spines and four to five longer setae, tarsus with ventromedial row of four spines. Dorsal surface of protibia (at rest) with faintly indicated basal sclerotized band; dorsal surface of protarsus slightly more sclerotized than ventral surface.

Abdomen. Tergites grey-brown to medium brown dorsally, lightening towards lateral margins, sternites light to dark tan; transverse striated bands not visible on abdominal sternites, barely visible on posterior 5th of terga I-VIII, nearly concolorous with rest of tergites. Abdominal sternite I sparsely clothed in long erect setae from anterior margin to near midline, abdominal segments II-VIII each with two sparse transverse bands of long erect setae, posterior margin of segment 8 denser setal band. Abdominal laterotergites concolorous with tergites, lacking distinct pigmented margins. Abdominal segment IX (pygidium) triangular in dorsal view, gradually reflexed to apex, sparsely clothed in short and mid length erect setae, dorsally more sclerotized in apical two-thirds with faint maculations; marginal row of 14-18 socketed spines present apical half, apex not forming distinct sclerotized projection. Pygopods short, subconical, each with 11-15 erect spines.

Variation. Little variation was observed between specimens beyond the number of spines on the legs and pygidium, and the overall degree of sclerotization.

Diagnosis.

Eleodes anthracinus larvae can be separated from most currently known Eleodes species based on their darker dorsal coloration on all segments, the absence of pigmented bands along the lateral margins of the thoracic terga, and the lack of a distinct sclerotized tooth at the apex of the pygidium. They can be distinguished from Eleodes carbonarius larvae by their lighter ventral segments and lack of distinct posterior pigmented bands on the abdominal terga. Larvae of Eleodes tricostatus (Say), another species in the subgenus Melaneleodes , are mentioned as being "nearly black" by McColloch (1918). However, no other diagnostic characters are mentioned that would separate them from the other Eleodes anthracinus or Eleodes carbonarius .

Figures

Figure 3. Dorsal habitus of four Eleodes species: A Eleodes (Litheleodes) extricatus B Eleodes (Melaneleodes) anthracinus C Eleodes (Melaneleodes) carbonarius D Eleodes (Tricheleodes) pilosus. Scale bar = 5 mm.

Figure 6. Lateral habitus of three Eleodes species: A Eleodes (Melaneleodes) anthracinus B Eleodes (Melaneleodes) carbonarius C Eleodes (Tricheleodes) pilosus. Scale bar = 5 mm.

Figure 7. Lateral habitus of the head and thoracic segments of three Eleodes species: A Eleodes (Melaneleodes) anthracinus B Eleodes (Litheleodes) extricatus C Eleodes (Promus) subnitens. Scale bar = 5 mm.

Figure 8. Eleodes (Melaneleodes) anthracinus, epipharnyx. asp = anterior spines, msp = medial spines, mst = microsetae, pap = sensory papillae, tor = tormae. Scale bar = 1 mm.