33 



The Mechanism of Evolution in Leptinotaesa 



These species are unmistakably distinct, easily separable in life, and while 

 some of them might be further divided to increase the number of species, I 

 can not at present find adequate basis therefor. 



In the working over of the literature of the taxonomy only important 

 references and synonyms are retained. Many references are vague, and so 

 many purposeless, incorrect citations and determinations appear that I have 

 omitted all but those necessary to trace clearly the correct name and synonymy 

 of each species. 



In the description of these species use must be made of a more precise 

 nomenclature than has hitherto been employed, especially of the elements of 

 the color-pattern which are constant and useful as differentials. In my 1906 

 paper (p. 60, figs. 1 and 2 ; p. 143, fig. 7) I give the arrangement and nomen- 

 clature of the centers of pattern-formation, which are designated in the main 

 from the selerite or portion thereof occupied, with the exception of the pronotum, 

 where an empirical lettering is used. 



DESCRIPTION OF THE SPECIES. 



UNDECIMLINEATA DIVISION. 



Elytral markings edged with an irregularly placed double row of impressed 

 punctations. 



LEPTINOTARSA UNDECIMLINEATA Stal. 



Myocoryna 11-lineata Stai. Ofv. af. K. Vet. Ak. Forh., 1858, p. 316.2. 



Chrysomela undecimlineata Stai. Monog. Chrys. d. Am., 1862, p. 163; 

 Chevolat, Dej. Cat. 3d ed. p. 421; Krantz, Berl. Zeit., 1874, t. I, f. 5. 



Leptinotarsa undecimlineata Stai in Gemminger et Herold, 1874, Catalog. 

 Coleop. t. XI, p. 3441; Jacoby, 1883, Biol. Centr. Am., vol. VI, pt. 1, 

 p. 234; Tower, 1906, Inv. Evol. Chrys. Beetles Gen. Lept., pp. 5-14. 



I have retained the name undecimlineata for the species inhabiting the 

 savannahs and foot-hills around the Gulf of Campeche in Mexico. This is the 

 form originally described by Stal. The habitat Mexico and the flavo-testaceous 

 basal joints of the antennae possessed by this form indicate clearly that Stal's 

 name should be retained for this species and that L. diversa, L. gtiatemalensis 

 n. sp., and L. panamensis should be given equal systematic rank. Stal's 

 description is as follows (Monog. Chrys. d. l.'Am., p. 163) : 



"Nigra, supra pallide flavescens; basi, apice maculaque media triangulari 

 capitis, maculis liturisque prothoracis nigris ; margine inflexo, sutura vittisque 

 quinque elytrorum aeneo-nigris. Long. 8J — 13, Lat. 5^ — 7 millim. 

 " Patria: Mexico, Costa Eica, Bogota, Bolivia. (Mus. Holm., etc.) 

 " Statura praecedentis. Ovalis, sat convexa, nigra, nitida, supra paUide 

 fliavescens vel straminea. Caput parce punctulatum, disco laevisculum, basi, 

 apice maculaque magna media triangulari nigris. Antennae apicem versis 

 sensim nonnihil incrassatae, articulis quinque ultimis subquadratis, clavam 

 vix formantibus. Prothorax elytris nonnihil angustior, antrorsum sensim 

 leviter angustatus, pone medium interdum parallelus, disco parce, subtiliter, 

 utrimque nonnihil densius et distinetius punctatus, litura media ut littera V 

 formata maculisque pluribus lateraUbus parvis nigris, angulis antieis mucro- 

 natis. S'cutellum laeve, seneo-nigrum. Elytra lateribus parallelis, subacervato- 

 seriatim distinete punctata, serie punctorum prima pauUo ultra tertiam partem 

 elytrorum extensa, margine inflexo, sutura, vitta suturali anteriore nee non 



