Diestostemma bicristata, McKamey, 2020

McKamey, Stuart H., 2020, Description of a new, unusual species of Diestostemma Amyot & Serville (Hemiptera, Cicadellidae) from Ecuador, ZooKeys 908, pp. 31-37 : 31

Diestostemma bicristata sp. nov. Figs 1-4 , 5-12

Diagnosis.

A small narrow species with a long head, pronotum with two long, weakly converging raised ridges, forewing with extra crossveins but only weakly reticulate. Aedeagus of male in lateral view with gradually recurved basiventral process.

Material examined.

Holotype male. "Ecuador. Napo. Km23, | Via Sta. Barbara-La | Bonita. 2400m. | 7-9 April 1986", "collected by | S.H. McKamey", and a red "HOLOTYPE | Diestostemma | bicristata | McKamey" (USNM). The left forewing and hind wing are damaged.

Measurements (mm).

Total length (from anterior of head to tip of forewings in repose) 13.8; crown length 2.6; transocular distance 2.8; interocular distance 2.0; distance between compound eye and mesal line 1.0; distance between ocellus and mesal line 0.5; pronotal disc maximum width 3.4; pronotal disc maximum length 3.0; forewing length 9.5; length of metathoracic femur 2.4; metathoracic tibia 4.8.

Description of the male holotype.

Body (Figs 1 , 2 ) lacking conspicuous, white powdery brochosomal coat when collected. Head (Figs 3 , 4 , 6 , 7 ). Crown maximum length 0.9 transocular distance and longer than interocular distance (ratio of 1.3) in dorsal view; anterior margin rounded with small apical, scarlike concavity (Fig. 7 ); epicranial suture indistinct; frons with deep muscle impressions laterally and planar medially, dorsal surface planar, weakly upturned distally; frontogenal suture extending onto crown to ocellar level. Ocellus located at level of anterior limit of compound eye, distinctly closer to eye than mesal line (ratio of distances between ocellus and eye with eye to mesal line of 0. 39). Epistomal suture indistinct. Clypeus anterior margin in lateral view at level of frons.

Thorax (Figs 1-4 , 6 ). Pronotum maximum width at posterolateral angles 1.1 times wider than transocular distance; maximum length 1.2 times longer than crown length; lateral margins convergent anteriorly; disc sculptured dorsally by punctures and callosities, punctures numerous and closer to each other in posterior half; pair of small transverse anterolateral pits just posterior to anterior margin, followed by smooth polished elevated area with pair of low, parallel median ridges; anteromesal area with elevated polished areas (callosities); posterior two-thirds developed into pair of ridges, gradually higher and more separated posteriorly (Figs 4 , 6 ); posterior margin sinuous with widened W-shaped outline; dorsolateral carina complete; lateral lobe of pronotum punctate, with median ridge, posterior margin projected into short thumb-like process. Mesonotum not punctate; scutellum dorsally smooth, lacking longitudinal carina; high and bluntly rounded until abrupt declivity just before acuminate apex. Forewing (Figs 1 , 2 ) coriaceous; surface strongly punctate, punctures minute distally; venation sclerotized and strongly elevated throughout; basal two-thirds with extra crossveins, distal third weakly reticulate. Hind wing membranous and lacking conspicuous brochosomes. Metathoracic leg with femoral setal formula 2:0:0:0 (AD1 and PD1); tibia with anteroventral row (AV) complete with cucullate (sensu Deitz 1975) macrosetae; anterodorsal (AD) and posteroventral (PV) rows complete with uniform non-cucullate macrosetae; posterodorsal (PD) row with smaller, more closely spaced, uniform, non-cucullate macrosetae; ratio of length of each individual tarsomere by total tarsus length (excluding pretarsus) equal to 0.5, 0.4 and 0.3, respectively.

Coloration. Head and thorax including legs pale brown except median of frons orange and forewings dark brown and hind wings smoky translucent. Abdomen dark brown.

Male terminalia. Pygofer (Fig. 10 ) dorsal margin convex, projecting dorsoposteriorly; inner surface without lobe in ventral view; posterior margin slightly concave at middle; microsetae distributed only on posterior lobe surface. Valve, in ventral view, transverse, subrectangular; fused laterally to pygofer lobe; articulated to subgenital plate. Subgenital plate (Fig. 9 ) 1.4 times longer than wide at base in ventral view; dorsal surface with tooth-like process near outer margin, associated with distal portion of style; posterior margin broadly rounded; microsetae distributed throughout ventral surface, tuft of longer setae at dorsoposterior angle. Style (Fig. 8 ), in dorsal view, with preapical lobe; apex of apophysis weakly acute, directed posteriorly; ventral margin without preapical dentiform processes. Connective (Fig. 8 ) 3.9 times longer than maximum width, sublinear posteriorly, narrowing anteriorly with anterior arms weakly separated in dorsal view; stalk much longer than arms. Aedeagus (Figs 11 , 12 ) strongly sclerotized; basally wide, narrowing distally into cylindrical, curved, sickle-shaped shaft in lateral view; shaft posterodistal portion membranous; basiventral process bulbous basally, abruptly constricted adjacent to where aedeagal shaft narrows, extending as narrow single process for half of remaining length before bifurcating and expanding into pair of long needle-like rami; rami of basiventral processes curved anterolaterally, distally divergent in posterior view (left fork broken in holotype).

Female unknown.

Distribution.

Known only from the type locality at the Kilometer 23 post along the road between Santa Barbara and La Bonita, at 2400 m elevation, in Napo Province, Ecuador. Biology and ecology unknown.

Etymology.

The specific name is feminine and based on the Latin " crista," for crest, in reference to its unique double-crested pronotum.

Discussion.

The new species is externally most similar to D. truncatipenne Schmidt, which also has an extended vertex and strongly raised forewing veins that are not very reticulate compared to most species of the genus; D. truncatipenne has been recorded only from Peru. The aedeagus is most similar to D. bituberculatum , which has more abruptly curved basiventral processes; D. bituberculatum is recorded from Brazil, French Guiana, and Guyana.

Figures

Figures 1 - 4. Diestostemma bicristata, sp. nov., holotype. 1 Habitus in lateral view (right side, image horizontally flipped) 2 habitus in dorsal view (scale = 2 mm) 3 Head and partial thorax, lateral view 4 head, pronotum, and partial pleura, oblique view. Scale bar: 5 mm.

Figures 5 - 12. Diestostemma spp. 5 Diestostemma sp., nymph, from Merida, Venezuela (courtesy of D. Takiya) 6 - 12 Diestostemma bicristata, sp. nov., holotype 6 head and partial thorax, ventroanterior view 7 head and pronotum, dorsoanterior view 8 connective and styles, dorsal view 9 pygofer base and subgenital plates, ventral view 10 pygofer and subgenital plate, lateral view 11, 12 aedeagus and basiventral process in lateral and posterior views, respectively (left ramus broken).