22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



"species groups." Were these nine species described solely with refer- 

 ence to one another, a separation would be effected on the basis of 

 group characters, not on specific characters, and the descriptions would 

 likely be inadequate for separating these species from their close allies. 

 Larvae of the same "species group" usually differ mainly in a cer- 

 tain set of characters which cannot be determined in advance. For 

 example, in the Ludiiis fallax group specific identification depends 

 primarily upon the relative length of the urogomphal prongs, the 

 number of "sensory" appendices on the second segment of the antenna, 

 and the shape of the posterior part of the frons, whereas in the aeri- 

 pennis group such characters have no specific value and identification 

 is made largely through the number of setae on the central dorsal area 

 of the ninth abdominal segment. In describing a larva that has no 

 known close allies there is no guide as to the structures that hold the 

 greatest specific value and, therefore, there is less chance of pre- 

 paring a description of lasting worth. 



LARVAL CHARACTERISTICS OE THE FAMILY ELATERIDAE 



The elaterid larvae are diverse in form, as shown in figure 8, but 

 family recognition is possible, in almost every instance, by the fol- 

 lowing combination of characters : Thoracic legs present, well devel- 

 oped, subequal, five-segmented (counting the terminal claw as a 

 segment) ; labrum absent or fused with clypeus and anterior margin 

 of frons into a rigid nasale (n, figs, i, a; 9, a, j) ; frontoclypeal area 

 usually lyre-shaped {fcl, fig. i, a; fig. 9, a, j) ; maxillae and labium 

 elongate, and fused into a single unit (figs, i, h; 9, c, h) with bases 

 inserted far behind the articulation of mandibles ; body straight with 

 9 abdominal segments visible dorsally, the ninth with or without 

 paired terminal processes (urogomphi) ; the tenth abdominal segment 

 bears the anus and lies ventrad (usually ventrocephalad) to the ninth 

 and may or may not be armed with sclerotized structures; spiracles 

 bifore. In the Cardiophorinae (fig. 8, o) each of the second to seventh 

 abdominal segments is divided transversely into 3 pseudosegments. 



A more extensive general description of an elaterid larva is given 

 by Henriksen (1911, pp. 226-231 ; translated into English on pp. 278- 

 283), and the family is separated in the larval keys of Roberts (1930) 

 and of Boving and Craighead (1931). A working knowledge of the 

 general morphology of elaterid larvae is given by Glen, King, and 

 Arnason (1943). 



