APPENDIX. 



TAXONOMY AND MORPHOLOGY OF THE LARVAL STAGES OF SCOBICIA DECLIVIS 



LECONTE. 



By Adam G. Boyixg. 



Scobida declivis LeConte belongs, according to the characters of 

 the larval stages, to the family Bostrichidae. In the recently pub- 

 lished Catalogue of the Coleoptera of America North of Mexico, 

 1920, by Charles William Leng, the genera Polycaon and Psoa are 

 placed in the tribe Psoini of the Bostrichidae but, according to the 

 larvae, these genera form, together with the genus Stephanopachys 

 (species investigated: S. substriatus Payk. arid S. pacificus Csy.). 

 which Leng place- in the tribe Bostrichini, a well defined family, the 

 Psoidae. This latter family is close to the Lyctidae and, like this 

 family, distinct from the Bostrichidae by having a strong epipharyn- 

 geal chitinization. a mandible with a large pseudomolar process, and 

 a large fleshy retinaculum. The larvae of the other genera listed by 

 Leng in the Bostrichidae substantiate the correctness of his concep- 

 tion of that family. 



The larvae of the Bostrichidae (in the present limitation) may be 

 characterized as follows : 



Bostrichidae. 19 



Habitus: Generally rather small, whitish, fleshy. Cyrtosomatic (curved like 

 a scarabaeid larva) in all stages except the first in which it is orthosomatic 

 (straight, with dorsal and ventral surfaces approximately of the same size). 

 Legs, or in first stage rudiments of legs, present ; no movable claw separated 

 from tarsus. With plicate, never shield-bearing thoracic and abdominal terga. 

 Ampullae not present ; terga never asperate, with or^ without soft hairs. Ten 

 visible abdominal segments. Ninth abdominal segment well developed, rounded, 

 unarmed in all stages, except the first in which it is armed with an unpaired, 

 chitinous. mucronate tail appendage or spur. No paired cerci. Tenth ab- 

 dominal segment small, entirely below ninth ; anal opening longitudinal. 



Head capsule: Head deeply retracted into prothorax, porrect ; with subrect- 

 angular outline, free portion subglobular. Occipital foramen ventral and op- 

 posite frontal region. Frons indistinct ; clypeus and labrum present, labrum 

 movable. Epicranium with rather short and curved hypostoma between man- 

 dibular condyle and end of cardo ; part behind cardo large. Definite gular 

 region not developed, submentum and the prothoracic presternal skin continu- 

 ous. 



Buccal rarity: Hypopharyngeal bracon absent. Hypopharynx fleshy; maxil- 

 lular areas elongate, soft, each with a longitudinal series of setae. Epipharynx 

 soft. 



Tentorium: Broad and strong. 



Ocelli: Not developed. 



Antenna: Of medium size or small. 



Mouthparts: Mandible gouge-shaped, inner surface subtetragonal, neither 

 with a true molar structure nor with pseudomolar process ; no retinaculum ; 

 no accessory mandibular condyle. Ventral mouthparts somewhat retracted. 

 Maxillary articulating area present. Cardo flat, quadrangular, not divided, 

 retracted below stipes. Stipites maxillae anteriorly convergent, connected with 

 maxillary articulating area and hypostoma. Maxillary mala divided into a 



19 This family characterization, as well as the taxonomic remarks given above, is part 

 of a joint study en the characterization of the coleopterous families according to their 

 larval stages, undertaken by Dr. F. C. Craighead and the author. 



49 



