Pseudocotalpa sonorica, Hardy, 1974

Van Dam, Matthew & Van Dam, Alex, 2006, Description of the Larva of Pseudocotalpa sonorica Hardy (Scarabaeidae: Rutelinae: Rutelini) with Notes on Life History, The Coleopterists Bulletin 60 (1), pp. 31-36 : 31-35

Adults of Pseudocotalpa sonorica

were collected north of the Osborne Overlook in the Algodones Sand Dunes, Imperial Co., California, USA (32859.2639N 115808.1019W) on 22 March 2002. An adult female was placed in a coffee can filled with moist sand from the dunes and subsequently deposited about 25 eggs. The resulting larvae were raised to the third instar on oak leaf mulch. The following description is based on two of these larvae. Specimens of adults and larvae are deposited to the Los Angeles County Museum of Natural History and Entomological Research Museum University of California Riverside.

Description. Head. Cranium ( Fig. 11 ) Greatest width of head capsule 6.8 mm. Epicranium light reddish-brown; surface smooth with setose punctures. Frontal suture absent. Epicranial suture only present at occiput. Setae spinelike or thin hairlike ( Fig. 11 ), becoming longer laterally. Two distinct pits on side of cranium. Genal margins marked with fine setae. Ocellus absent. Clypeus: Form subtrapezoidal. Preclypeus smooth pale, tan, with row of minute setae bordering top; postclypeus same color as cranium. Labrum: Form subovate, right side with indentation on edge. Surface convex, except distal third flattened, setigenous punctate. Only distinct setae on surface are fine, hairlike setae, all in deep pits; two on upper half near center; one seta on each side of upper half near edge; one seta on each side of lower half near edge and two near center. Epipharynx: Form subovate. Haptomerum beaklike with about 29 heli. Epizygum present. Corypha and acroparia merged bearing 20 setae. Acanthoparia bearing 21 left, 20 right recurved spines. Plegmatium lacking. Gymnoparia narrow. Chaetoparia with many thick setae near center and thinner setae laterally ( Fig. 1 ). Pedium present, well defined. Haptolachus with four sensory cones; crepis absent, sulcus present where crepis would be. Dexiotoma elongate. Laeotorma with rounded, posteriorly produced pternotorma. Right Mandible: Scissorial region with two scissorial teeth ( Fig. 3 ). Dorsoexterior mandibular region distinctly concave; top of region with one seta; medially with distinct pit with seta. Dorsal surface with 18 dorsomolar setae. Lateral face with 24 setae. Ventral surface, with ovate stridulatory area, rows progressively smaller towards apex ( Fig. 3 ). Molar area with three molar lobes, brustia with seven setae, with 12 basolatera setae. Left Mandible: Scissorial area with two teeth. Dorsoexterior mandibular region distinctly concave; top of region with one seta; immediate right distinct pit with seta. Dorsal surface, with 20 dorsomolar setae. Lateral surface with 29 setae. Ventral surface with ovate stridulatory area, ridges progressively smaller towards apex. In molar region, M1 a raised transverse lobe, M2–3 inverted V shape and M3 larger than M2, brustia with ten setae U shaped; acia present. Maxilla: Cardo with two rows fine setae. Stipes in ventral view with one row of about eight setae continuing to dorsal area; in dorsal view with dense fine setae especially near large truncate stridulatory process, setae becoming thicker near palpus. Stridulatory area with three to five flattened curved spines and broad truncate process distally ( Fig. 5 ). Lacinia with many stout setae ( Fig. 6 ) and two unci. Galea with one conical uncus. Palpus four segmented; segment four with concavity near middle; third segment with two long setae; one long seta near base of palpus. Labium: Interior surface of glossa with many stout spines, which are longer near palpus. Hypopharyngeal sclerome slightly concave, with greatly raised process on right. Lateral lobe with many fine setae ( Fig. 2 ). Antenna: Five segmented, scape round, about three times diameter of pedicel. Segment three about two times as long as pedicel; fourth segment with distinctive raised lobe structure; fifth with about 12 sensory spots, five dorsal, six ventral and one on outer side, and sense cone present ( Fig. 4 ). Thorax. Sparsely setose with fine setae. Thoracic sclerite weakly formed, color pale tan. Spiracle respiratory plate C-shaped, 0.75 mm in diameter; bulla raised. Legs: Femur, trochanter and tibiotarsus of all legs with many fine setae ( Fig. 8 ). Protibiotarsus with three distinctly flattened setae near apex, almost fossorial ( Fig. 10 ). Protarsungulus with two setae tips elongate. Meso and metatarsunguli progressively reduced in length, both with two setae present. Abdomen. Spiracles 1–4 diameter 0.95 mm; spiracle 5 diameter 0.65 mm; spiracles 6–8 diameter 0.35 mm. Segment I: Prescutum with 81 setae, of those 11 long, hairlike, same diameter as others; subscutum with 13 long setae; scutum with about 85 setae; spiracular area with 34 setae; scutellum with about 75 setae. Segments II–VII: Prescutum with about 100 setae; scutum and scutellum with same dense setae. Segments VIII-IX ( Fig. 9 ). Segment X with dorsal impressed line present; palidia absent; many hamate setae near anal slit ( Fig. 7 ).

Biology

P. sonorica were collected flying at dusk between 7:30 and 8:00 pm. Hardy (1976) also noted the crepuscular habits. They were collected on evenings with an air temperature of about 21–248C with light wind. Windy evenings disturbed the beetles, producing few individuals of P. sonorica . Specimens were taken on 22-iii-02 (31specimens), 31-iii-03 (14), 29-iii-05 (7), 5-iv-05 (39). They fly out of bushes of Croton wigginsii Wheeler , Eriogonum deserticola S. Watson and Dicora canescens A. Gray. Both C. wigginsii and E. deserticola are endemic to the Algodones Sand Dune system. P. sonorica can also be collected with a mercury vapor bulb or any florescent light. Females were located on the sand by the sound of males buzzing their wings in a mating swarm, consisting of a female and several males fighting over her. Females do not seem to be strongly attracted to light sources.

The sand dunes are divided by HWY 78 and on the north side of the HWY there is plenty of vegetation and on the south side there is hardly any. This is due to the off roading of motor vehicles. There are almost no beetles on the south side of the HWY. Pseudocotalpa larvae may be feeding on bushes that have been buried by sand or are feeding on the roots of the plants. More investigation needs to be done to identify what their natural food source is.

P. sonorica is not completely allopatric with P. andrewsi , both ranges overlap slightly in the dunes. P. sonorica is collected at or near the peaks of the dunes whereas P. andrewsi is primarily collected in the habitat at the base of the dunes. The two species may be feeding on different host plant species. The vegetation at the base of the dunes is different from the top.

Remarks. The larvae of Pseudocotalpa may be distinguished from other similar larvae based upon the following differences. Pseudocotalpa is placed in the tribe Rutelini and differs from similar tribes in the Rutelinae according to Ritcher’s key (1966) on the basis of P. sonorica having two or more dorsal sensory spots on the terminal segment of the antenna. With in this tribe Pseudocotalpa is most similar to Cotalpa Burmeister. Pseudocotalpa differs from Cotalpa by having short spinelike setae on the head. Also there are two pits on the head capsule that Cotalpa does not have. The anterior annulet in abdominal segment VII is also covered in a dense covering of short setae whereas Cotalpa is without such coverage. Pseudocotalpa sonorica runs to Cotalpa in both the keys of Ritcher (1966) and Jameson and Morón (2001). Pseudocotalpa differs from Parastasia Westwood and Macraspis Macleay because it does not have palidia. It differs from Rutela because Pseudocotalpa lacks plegmata on the epipharynx. Pseudocotalpa differs from Pelidnota Macleay and Chrysina Kirby in that Pseudocotalpa has a head densely covered with setae and the haptomerum is beaklike and it has three to five maxillary stridulatory teeth. Pseudocotalpa differs from Paracotalpa Ohaus in that the setae on the head of Pseudocotalpa are short and the labrum is without two crescent-shaped ridges. Also in Pseudocotalpa the spiracles on abdominal segments VII–VIII are much smaller than the preceding segments.

Figures

Figs. 7–11. Pseudocotalpa sonorica, third-instar larva. 7) Ventral view abdomen seg. X; 8) metathoracic leg; 9) lateral view abdomen; 10) protarsungulus-tibiotarsus; 11) head, frontal view.

Figs. 1–6. Pseudocotalpa sonorica, third instar larva. 1) Epipharynx; 2) labium; 3) mandibles left, right dorsal view, mandibles ventral view left, right; 4) last antennal segment, dorsalview; 5) maxillary stridulatory area; 6) left maxilla, central view.