Polemistus divaricatus Ma et Li, 2020

Ma, Li & Li, Qiang, 2020, The genus Polemistus de Saussure in China with descriptions of four new species (Hymenoptera: Crabronidae), Zootaxa 4852 (4), pp. 475-484 : 478-480

2. Polemistus divaricatus Ma et Li , sp. nov.

( Figure 2 )

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Material examined. Holotype: ♀, China: Yunnan: Jinghong: Xishuangbanna National Forest Park, 21°58'N 100°51'E, 2003.VII.31, coll. Tingjing Li ; Paratype: 1♀, same to the holotype; 1♀, China: Yunnan: Jinghong, 21°59'N 100°46'E, 2003.VII.30, coll. Peng Wang. All specimens are deposited in the Insect Collections of Yunnan Agricultural University, Kunming, Yunnan Province, P. R. China .

Diagnosis. Unlike the other Chinese Polemistus , this species and P. dudgeoni have triangular or subtriangular clypeus. P. divaricatus differs from P. dudgeoni (Nurse, 1903) by the following combination of characters: interantennal tubercle somewhat broad and long, divaricated apically ( Fig. 2b ); lower frons with well-defined frontal median carina; scape long, length of scape: length of flagellomeres I–IV = 17: 13; free margin of clypeus markedly produced, forming a long triangular tooth medially ( Fig. 2a ).

P. dudgeoni (Nurse, 1903) has the following characters: frons without tubercle; frontal median carina absent; length of scape equal to flagellomeres I–IV combined; free margin of clypeus subtriangular, anterior margin rounded.

Description. Female. Body length 4.0– 4.3 mm. Black. Mandible apically, palpi, antenna beneath largely reddish brown; labrum, antenna above and last gastral segment dark brown; tegula fulvous to dark brown; forewing veins fulvous; base and apex of fore femur, fore and mid tibiae, tarsi, and outer margin of hind tibia reddish brown. Clypeus with sparse, short and silvery setae, mixed with several long, brown setae apically.

Mandible bidentate apically, outer tooth large, acute, inner tooth broad, blunt ( Fig. 2a ). Labrum triangular. Clypeus flat, with midsize, sparse punctures, free margin markedly produced, forming long triangular tooth medially, slightly reflected ( Fig. 2a ). Interantennal tubercle somewhat broadened, long, divaricated apically ( Fig. 2b ). Median and lower frons distinctly concave, lower frons with conspicuous frontal median carina ( Fig. 2a ), and with sturdy, dense and transverse rugae medially, laterally with irregular rugae; median frons with several inconspicuous, curving rugae. Upper frons with midsize to large, sparse punctures. Ocellar triangle slightly convex, with midsize, dense punctures medially, and with fine, sparse punctures laterally. Vertex behind ocelli with dense, slender and transverse striation, laterally with conspicuous transverse carina on each side, connecting hindocellus and orbital furrow ( Fig. 2b ). Gena and head underside with midsize, dense punctures, slightly coriaceous. Occipital furrow narrow dorsally, somewhat broadened ventrally, conspicuously crenulate. Inner eye orbits slightly convergent toward clypeus, furrow between sturdy marginal carina and eye narrow, conspicuously crenate; outer orbital furrow with carina same as inner one, except inconspicuously crenate ventrally. Ratio of HW: HLD: HLF = 57: 31: 58. HW: EWd: IOW: EW: OOW: TW: OCW: EL = 57: 16: 2: 21: 2: 19: 1: 52. AOD: WAS: IAD = 3: 5: 8. POD: OOD: OCD = 7: 7: 13. Length of scape: of pedicel: of flagellomere I: width of flagellomere I: length of flagellomere II: width of flagellomere II = 23: 5: 3: 4: 4.5: 5.

Pronotal collar simple and incomplete, just lateral corner present. Mesoscutum coarsely coriaceous, with contiguous, large punctures, anterior slope nearly vertical and very high, posteriorly with several, irregular, longitudinal rugae, longer in middle; admedian line conspicuous, only present anteriorly on mesoscutum; notaulus shallowly grooved and crenate, reaching one third of mesoscutum length; parapsidal line impressed. Mesopleuron coarsely coriaceous, with midsize and dense punctures, episternal sulcus, omaulus and hypersternaulus distinctly crenate, scrobal sulcus lacking ( Fig. 2d ). Propodeal enclosure long, without delimiting carina, median area with sturdy reticulation, lateral area with sparse, slender and oblique longitudinal rugae ( Fig. 2c ); posterior surface with much narrowed median groove, shiny, sides of groove large, nearly smooth, with fine, sparse punctures and some inconspicuous striation or slightly coriaceous, laterally and posteriorly irregularly reticulate ( Fig. 2c ). Lateral surface of propodeum with dense, sturdy and longitudinal rugae.

Petiole slightly longer than wide, dorsal surface with shiny, broad and longitudinal groove medially, and one conspicuous lateral carina on each side ( Fig. 2e ). Gastral terga I–II shiny, with fine, sparse punctures, remainder half mat, finely coriaceous and with fine, dense punctures. Gaster somewhat constricted between segments I and II. Pygidial area lacking.

Male. Unknown.

Distribution. China (Yunnan).

Etymology. The name, divaricatus , is the Latin past participle of the verb divaricare (to stretch apart, to spread out), referring to the interantennal tubercle somewhat broadened and long, divaricated apically, one of the main recognition characters of this species.

Figures

FIGURE 2 Polemistus divaricatus Ma et Li, sp. nov. (Holotype, female). a. Frontal view of head; b. Dorsal view of head; c. Dorsal view of propodeum; d. Mesopleuron; e. Dorsal view of petiole and gastral tergum I (scale line for d: 1 mm; for a–c and e: 1.31 mm).