Diabrotica palpalis Jacoby 1887: 520
Panama, Volcan de Chiriqui
BMNH, lectotype, female, verified
hybrida Jacoby 1887: 561, nomen nudum
Body length 6.9-7.0 mm. Body width 3.5-3.6 mm. Head basic color black. Antennae moniliform, uniformly yellow. Maxillary palpi black or chestnut, penultimate joint of maxillary palpi strongly incrassate, labrum black. Pronotum yellow or mustard yellow, quadrate, weakly bifoveate, with wide shallow foveae, shagreened with minute wrinkles. Scutellum black or amber brown. Elytra yellow or rufous, maculate, with short black lines or small spots, one sutural (near scutellum), one humeral, one in middle and two behind middle of each elytron. Elytral epipleura completely yellow, sutural angle of elytra round, punctation scattered, fine. Abdomen yellow. Legs yellow.
Jacoby (1887) wrote in the diagnosis of D. palpalis: "?. Antennae with short and robust joints; palpi strongly incrassate. ?. Antennae and palpi of normal structure." We studied the type and paratypes of D. palpalis in BMNH collection. The female type matches the Jacoby's description of male. Antennae in female type are moniliform with short and robust joints, palpi strongly incrassate. Paratypes include two females and one male. Female paratypes are quite different from the female type in antenna and palpus structure. Their antennae are filiform and palpi are not incrassate. Antennae and palpi of the male paratype are the same as in female paratypes. So, paratypes of D. palpalis definitely belong to another species. We are unable to find any specimens in the Jacoby's collections in BMNH and in MCZ matching the female type of D. palpalis .
Potential problems with identification
Diabrotica palpalis Jacoby is similar to D. pl1n. They can be separated by the following features: penultimate joint of maxillary palpi is not incrassate in D. pl1n, but strongly incrassate in D. palpalis; elytra with three black spots on each elytron, one on basal part of elytra and two behind the middle in D. palpalis, while only one small black spot is behind the middle on each elytron in D. pl1n; humeral vittae occupy nearly the full length of elytron in D. pl1n, but only short humeral spots present in D. palpalis; scutellum is yellow in D. pl1n, but black or amber brown in D. palpalis .