Aphodius (Heptaulacus)

Frolov, Andrey V., 2009, Larval morphology of Aphodius sus (Herbst) and A. variicolor Koshantschikov (Coleoptera: Scarabaeidae: Aphodiinae), Zootaxa 2169 (1), pp. 45-54 : 45-50

Aphodius (Heptaulacus) sus (Herbst, 1783)

Figs. 1 –15, 20, 21, 31, 33, 35, 37, 39

Aphodius sus ( Fig. 2 ) is widely distributed in the south of European part of Russia up to Smolensk, Tula, Saransk, Ul'yanovsks and Ufa in the north ( Kabakov & Frolov 1996). In Dosang environs, it is a common species with adults occurring in large numbers in horse dung in the fall .

FIGURES 8–23. Aphodius , anal sternite. Figs. 8–15, 20, 21— A. sus. Figs. 16–19, 22, 23— A. variicolor . Figs. 8 – 19. Variability of raster pattern. Figs. 20, 22. Raster setae. Figs. 21, 23. Anal segment in caudal view. Scale bar 0.5 mm.

FIGURES 31–40. Aphodius , details of larval morphology. Figs. 31, 33, 35, 37, 39— A. sus. Figs. 32, 34, 36, 38, 40 – A. variicolor . Figs. 31, 32—maxillae and hypopharynx in dorsal view. Figs. 33, 34—labrum in ventral view. Figs. 35, 36—schematized chaetotaxy and of left lacinia and galea in dorsal view. Figs. 37, 38—middle legs. Figs. 39, 40—antennae.

Material examined. Forty-six third-instar larvae were collected on 16.V. 2007 in grass roots at the depth of 10–15 cm in riverine secondary forest near Dosang village . All larvae were about the same size and similar exteriorly. Twenty living larvae were taken to the ZIN laboratory and in a month eight adults were obtained .

Third-instar larval description. Larva of typical C-shape form ( Fig. 1 ). Head width: 1.16±0.04 mm, length (without labrum): 1.01±0.05 mm. Head surface shiny, yellowish-brown with unclear pattern of small, brown spots on pleural sclerites near frontal sutures ( Fig. 3 ). Medial part of pleural sclerites and base of frons a bit darker than remaining part of the head capsule. Frontal sutures are visible as very fine, darker lines.

Epicranial suture approximately 2 times shorter than frons height. Each pleural sclerite with 5 long setae: 3 near palpifer, 1 in the center, and 1 near epicranial suture. A number of shorter setae located on pleural sclerite without an obvious definite pattern. Frons with 5 pairs of setae: 2 short in the center of frons, 1 short medially, and 2 long laterally.

Clypeus trapezoidal, yellowish-brown, with 2 pairs of long setae and 1 pair of short setae laterally. Basal part of clypeus (3/4 length of clypeus) is darker than apical quarter. Surface of clypeus without prominent tubercles.

Labrum trilobed, with 2 pairs of long setae on dorsal surface, and 24 short to relatively long setae on the distal margin. Ventral side of labrum with 1 pair of short setae basally (Fig. 33).

Mandibles triangular, asymmetrical. Left mandible slightly longer than right mandible, scissorial part of left mandible wider than in right mandible ( Figs. 4–7 ). Base of mandibles light brown, scissorial and molar part almost black.

Maxillae symmetrical with respect to each other (Fig. 31). Cardo with 4 short setae: 2 on ventral side and 2 on lateral margin near base of stipes. Ventral side of stipes with long proximal and short distal setae, dorsal side with a row of 7–9 stridulatory teeth and 2 short setae near base of palpifer. Palpifer without stridulatory teeth, with 1 short seta ventrally. Maxillary palpus with 4 palpomeres; 1st and 4th palpomeres with 1 seta each, 3rd with 2 setae. Ventral side of galea with longitudinal row of 6 short setae. Dorsal side and apex of galea with 5 relatively long setae. Dorsal side of lacinia with 5 long and thick setae and 1 short setae, ventral side with 1 long and thick seta apically and 1 short seta basally. Apex of lacinia tridentate.

Legs are about the same size, anterior legs slightly shorter than others (Fig. 37).

Anal sternite with 30–40 relatively long, strongly sclerotized spinules flattened and strongly widened apically (Fig. 20). The spinules are not arranged in rows or, in some specimens, medial spinules appear to be arranged in 2 or even 4 irregular longitudinal rows of 6–7 spinules each (Figs. 8–15). Lower anal lobe sinuate in the middle (Fig. 21).

Lateral bulges of abdominal segments with 2 setae. Each fold of abdominal tergites with transverse row of short, thick setae.

Diagnosis. The larvae of A. sus can be separated from the majority of other described larvae by the combination of characters of the maxilla, anal sternite, abdominal segment chaetotaxy, and head coloration. In the Krell's (1997) key to Central European Aphodius larvae, the larvae of A. sus goes to the couplet with A. lividus (Olivier) , but the characters provided are not enough to distinguish these two species. They probably differ in thorax and abdomen chaetotaxy or shape of galea apex but, due to lack of A. lividus larvae, I cannot examine these characters.

Figures

FIGURES 1–7. Aphodius sus. Fig 1. Larva in lateral view. Fig. 2. Imago in dorsal view. Fig 3. Head of larva. Figs 4–7 Mandibles of larva (4, 5—in dorsal view, 6, 7—in ventral view; 4, 7—left, 5, 6 —right).