44 The Mechanism of EvoLUTioisr in Leptinotarsa 



BlOTYPE NIGBOPUNCTATA StUBM. 



Similar to signaticolUs (plate 2, fig. 2), but with elytra having numerous 

 large black puuctations, which may or may not show arrangement in pattern of 

 ten irregular double rows ; punctures often confluent, giving the appearance of 

 longitudinal vittae. Appears also in experiment, most often as a dominant, and 

 when isolated breeds true; female sex-linked, but not uniformly so. (See also 

 Jacoby, 1883, p. 232, who had Sturm's specimens for study.) Eecorded from 

 Cuernavaca, Cuautla, Estado de Morelos, Atlixco, Estado de Puebla. 



MULTIT/ENIATA DIVISION. 

 LEPTINOTARSA MULTIT^NIATA StIl. 



Myocoryna multitwniata St§,l, 1859. Ofv. af K. Vet. Ak. Forh., p. 317.4. 



Chrysomela multitwniata St§,l, 1862. Monog. Chrys. Am., p. 164. 



Leptinotarsa multitwniata St§,l. Gemminger et Harold, 1874, Catalog. 

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

 p. 253; Tower, 1906, Inves. Evol. Chrys. Beetles, Gen. Lept., Carnegie 

 Inst. Wash. Pub. No. 48, pp. 7, 18. 



This species has given me more trouble in the effort to untangle its taxonomic 



relations than all of the others combined. It is a plastic, variable, polymorphic 



form, showing curious phenomena of heterogeneity which I shall discuss later. 



From present data I have arranged the species and its minor forms as follows : 



L. multitwniata StS.1. 



Habitudinal variation: multitwniata StM. 

 Recurrent mutation: melanothorax St&.l. 

 Saltation: tacubayaensis nov. var. 

 Biotypes: 



multilineata Stil. 

 obscura nov. var. 

 Habitudinal variation: intermedia nov. var. 



Saltation, melanothorax St§,l. 

 Habitudinal variation: variabilis nov. var. 

 Recurrent mutation: melanothorax Sta.1. 

 Biotypes: 



Red hypodermal color. 

 Orange hypodermal color. 

 Yellow hypodermal color. 

 White hypodermal color. 



Habitudinal variety L. MULTiT^NiATA-MXJi.TiT.a:NiATA Stal. 



Stal's description of the typical muUitceniata form, taken from his monograph 

 (1862), is as follows : 



" Ovalis, supra flavescens, subtus cum antennis, pedibus, maculis prothoracis, 

 limbo scutelli, sutura vittisque quinque, exteriore intramarginali, elytrorum, 

 nigra ; maculis pectoris limboque apicali segmentorum ventris flavis ; elytris 

 minus regulariter seriatim punctatis. Long. 10, Lat. 6| millim. 



" Patria: Mexico (Mus. Berol., Coll. Dohrn). 



" C. multilineata simillima, prothorace latiore, elytris regularius seriatim 

 punctatis differt. Ovalis, sat convexa, nigra, nitida. Caput sat dense, distincte 

 punctatum, vittis duabus obliquis, basi conjunctis, flavis. Antennae articulis 

 quinque apicalibus transversis, clavam sat distinctam formantibus. Prothorax 

 elytris nonnihil angustior, sat convexus, antrorsum sensim, augustatus, disco 

 parce, subtiliter, utrimque densius, subfortiter punctatus, flavescens, maculis 

 compluribus lateralibus lituraque media ut littera V formata, plus minus con- 

 fluentibus, nigris ornatus. Scutellum flavescens, plus minus late nigro-limba- 



