38 The Mechanism of Evolution in Leptinotaksa 



the stripe, with dense black spots on the edge, and more rarely the stripe breaks 

 longitudinally into two, not unlike L. angustovittata Jacoby. All stages occur 

 in the same restricted localities and frequently have been reared in the progeny 

 obtained from a single pair of parents. Sexes distinguished as in diversa. 



Distribution: Mexico: Desert areas in headwaters of Eio Balsas Valley. 

 Eecorded: Teuhuacan, El Kiego, Pantzingo, Venta Salada, Mihuatlan (Estado 

 de Puebla), in Guerrero. 



Food: S. lanceolatum. 



Juvenile stages: Like those of L. diversa. 



Habitat: A strictly desert form inhabiting some of the most extreme desert 

 areas in America. It is always limited in its habitat to edge of water-courses, 

 either natural or artificial, and its distribution is, therefore, extremely local in 

 character. It has the capacity for surviving through long periods almost free 

 from desiccation by hibernating in earthen cells, which condition, while it 

 apparently allows air to enter, prevents evaporation from the cell, thus retaining 

 the necessary water to enable the animal to pass the critical season. 



Source of Materials: All materials in experiment have come from a point 

 1 kilometer south of El Riego near Teuhuacan in Puebla. Stocks were obtained 

 as follows: No. 900 in May 1907; No. 901 in June 1909. 



LEPTINOTAKSA PANAMENSIS N. SP. 



Leptinotarsa undecimlineata Stai, 1862, Monog. Chrys. d. Am., p. 163. StS,l 

 gives Costa Rica, Bogota, and Bolivia as localities for undecimlineata. 

 In Panama I have not found undecimlineata, but an allied form here 

 described, and in the lower portion of Costa Rica panamensis is also 

 the only species present. Dr. Calvert, from Cantago, Costa Rica, sent 

 me all stages of panamensis. All references to undecim,lineata from 

 these regions are therefore probably to panamensis as here described. 

 Also quoted by Jacoby, 1882 (Tower, 1906), and many museum speci- 

 mens in Europe and America from Panama and Costa Rica are so 

 labeled. 



Imago (plate 1, fig. 4; plate 2, fig. 9). — Above: Head and pronotum bright 

 yellow, Avith black markings ; mouthparts black with yellowish hairs ; elytra 

 ivory white, often with greenish tinge marked with black longitudinal unbroken 

 stripes, 5 or 6 on each elytra, with costal border strongly inflexed, punctate, 

 black. Below : All parts deep, shiny black ; hind wings well developed, polished, 

 blackish, deepest on costa and toward base ; antenna?, basal four or five joints 

 brownish to yellow, variable, terminal joint short, conical. Seventh to eleventh 

 broad as long and minutely pubescent. Palpi, basal and first joint brownish to 

 yellow, variable; third joint enlarged distally to breadth equal to its length, 

 terminal joint short, conical, black. Head : Anterior lateral epicranial spots 

 fused into heart-shaped spots and prolonged caudad to meet fused portion of 

 lateral epicranial spots. Posterior epicranial border and lateral border to eyes, 

 punctate. Pronotum with all elements present, small, variable, with little or no 

 fusions. 



Size: On average smaller than L. undecimlineata Stal. Male 6.5 to 11 mm. 

 long, 4 to 6 mm. broad ; female 7 to 12 mm. long, 4.5 to 7 mm. broad. 



Sexes: Female with sternal sclerite of last abdominal segment rounded, 

 slightly truncate ; male with same sclerite sharply truncate, with median groove, 

 variable in length reaching anteriorly. In general the males smaller than the 

 females, and less broadened posteriorly. 



Food: Solanum diversifolium. 



