Sharpheaded Sharpshooter

Differentiated from D. robinsoni on the basis of the form of the male 2S apodemes: Apodemes 2S produced most strongly mesad on lower halves vs. robinsoni : Apodemes 2S produced most strongly mesad near apex or with both lobes subequal (Hamilton, 1985) Characters as in D. robinsoni , but 2S apoclemes expanded on lower halves, overlapping when mature and aedeagus shorter. - Hamilton, 1985 Given the ambiguity and contested validity of this species, most images that could be either D. robinsoni or D. zeae (excluding other members of the complex and the externally similar D. mollipes ) are placed under D. robinsoni on BugGuide, for now. This is a cryptic species which may not be differentiable from D. robinsoni without dissection or DNA barcoding. Treated as a jr. syn. of Draeculacephala robinsoni Hamilton, 1967 in Dietrich, 1994 . Revalidated in Chandler & Hamilton, 2017 on the basis of DNA barcoding. Dietrich considered D. zeae and D. sphagneticola Hamilton to be junior synonyms of D. robinsoni , while continuing recognition of D. portola Ball and D. paludosa Ball & China as valid species. Molecular work using the COI gene for barcoding (Fig. 31) has revealed that there are two clusters for these species, separated by a genetic divergence value of 1%, with the first cluster containing specimens placed as D. robinsoni and D. sphagneticola that are intermixed (indicating a single species, D. robinsoni ), and the second cluster holding representatives of the other names that cluster genetically tightly at a value less than 1%, but separately as three species: D. zeae , D. portola , and D. paludosa . Since D. zeae is in a separate cluster from D. robinsoni , and clusters tightly but separately with the two species recognized as such based on external characters by Dietrich, it is here treated as a species on this basis, and supported by the differences in morphological characters and color patterns discussed by Hamilton (1985b). This low level of divergence in the COI gene has been documented for other groups where morphological characters can be used for separation (Hebert et al., 2004; Gibbs, 2010). (Chandler & Hamilton, 2017)