Psenulus pallens sp. nov.

Figs 4F-4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17F, 18K, L, 19K, L, 20F, 21F, 22A-D

Diagnosis.

Psenulus pallens sp. nov. is readily distinguishable from most other species of its genus by its remarkably light coloration with black patches restricted as described below (Figs 4F, 5F, 22A-22D). From other similarly light-coloured species, it differs from P. lamprus van Lith, 1972 of Sulawesi by its less reticulated propodeum with polished area dorsally (Figs 14F, 15F); in the female of the latter (the male is unknown), the back and most of the sides of the propodeum are densely and coarsely reticulate. The female of P. pallens also differs from P. lamprus in its cluster of denticles on the apex of hind tibia (Fig. 18K) as opposed to three reddish spines in the latter. It shows also considerable difference in the shape of the ventral clypeal margin (Figs 20F, 21F) with that of similarly coloured P. lamprus and P. interstitialis, the latter two with small teeth, reduced to denticles and no emargination in-between. Psenulus impressus van Lith, 1976 of Luzon has the episternal sulcus foveolate. Psenulus singularis van Lith, 1962 also from Luzon has a distinctly shaped clypeus with the median section of the ventral margin bluntly protruding.

Material examined.

Holotype: China, Hong Kong • ♀; Mang Kung Wo; 22°22'06"N, 114°15'12"E; 60 m a.s.l.; 18 May-01 Jun. 2019; C. Barthélémy leg.; Malaise trap, ref.: M416CHy1A; CAS . Paratypes: China, Hong Kong • 2♀; Sam A Tsuen; 22°30'55"N, 114°16'16"E; 11-27 Dec. 2017; C. Taylor and U. Chang leg.; Malaise trap; HKU • 1♀; Sam A Chung; 22°30'33"N, 114°16'20"E; 17-30 May 2018; ibid; HKU • 1♀; Mang Kung Wo; 22°22'06"N, 114°15'12"E; 60 m a.s.l.; 18 May-01 Jun. 2019; C. Barthélémy leg.; Malaise trap, ref.: M416CHy1B • 1♀; ibid; 29 Jun.-13 Jul. 2019; ibid; ref.: M423CHy1; CBC • 1♀; ibid; 05-19 Oct. 2019; ibid.; ref.: M443CHy1; CAS • 1♀; ibid.; 19 Oct.-03 Nov. 2019; ibid.; ref.: M447CHy3; CAS • 1♀; ibid.; 03-16 Nov. 2019; ibid.; ref.: M449CHy1; CAS • 1♀; ibid.; 16-30 Nov. 2019; ibid.; ref.: M453CHy1; CBC • 2♀; ibid.; 14-28 March 2020; ibid.; refs: M477CHy1A and 1B; CBC • 1♀; ibid.; 11-25 Apr. 2020; ibid.; ref.: M483CHy1; CBC • 1♂; Pak Sha O; 22°26'59"N, 114°19'04"E; 70 m a.s.l.; 15-29 Sep. 2018; ibid.; ref.: M368CHy1; CBC • 1♀; ibid; 24 Aug. 07- Sep. 2019; ibid; ref.: M434CHy5; CBC • 1♀; ibid.; 21 Sep.-05 Oct. 2019; ibid.; ref.: M440CHy4; CBC • 1♀; ibid.; 28 Mar.-11 Apr. 2020; ibid.; ref.: M480CHy1; CBC .

Standard ratios.

Males (n = 1): L = 4.6 mm; CR = 1.35; OOR = 0.46; FLR = 1.13; FRR = 0.59; MR = 1.65; OMR = 0.94; PR = 0.81; PFR = 0.81. Females (n = 16): L = 4.9-6.0 mm (mean = 5.45 mm); CR = 1.22-1.42 (mean = 1. 32); OOR = 0.47-0.65 (mean = 0.58); FLR = 1.22-1.67 (mean = 1.38); FRR = 0.42-0.63 (mean = 0.58); MR = 1.33-1.77 (mean = 1.55); OMR = 0.83-0.97 (mean = 0.89); PR = 0.82-1.29 (mean = 1.08); PFR = 0.75-0.97 (mean = 0.85).

Description.

Male: Antenna without tyloids. Clypeus (Fig. 21F) with two well-developed ventral teeth separated by triangular emargination, remainder of clypeal margin straight. Subantennal carina well developed; interantennal carina narrow, not broadened dorsally (Fig. 7F). Mesosoma mostly polished, mesoscutum lightly and minutely punctate (Fig. 11F), punctures very sparse elsewhere on mesosoma; prescutal sutures short, extending shortly beyond anterior level of tegula; episternal sulcus simple (Fig. 13F); propodeal enclosure with several pairs of longitudinal carinae; rear of propodeum (Fig. 15F) dorsally smooth, ventrally and laterally coarsely reticulate with reticulations encroaching on posterior part of side of propodeum. Petiole subcylindrical, T1 relatively low (Fig. 5F). Fore wing (Fig. 19L) with first recurrent vein more or less interstitial with first and second submarginal cells, second recurrent vein meeting third submarginal cell at about one-eighth of cell length from base.

Head black with silvery appressed pubescence (Figs 7F, 9F); antenna with scape, pedicel and base of flagellum ventrally yellow, dorsum and terminal segments of flagellum black; mandible yellow with black tip. Mesosoma and legs mostly yellow, hind legs reddish from trochanter to tarsus, the following black: three small spots on mesoscutum, along posterior margin of mesoscutum and scutellar groove; mesosternum, encroaching onto base of mesopleuron; propodeal enclosure posteriorly. Petiole basally yellow, becoming reddish apically; remainder of metasoma reddish.

Female: Clypeus with small ventral teeth separated by shallow emargination (Fig. 20F). Subantennal carina distinct but not protruding beyond pubescence (Fig. 6F). Mesosoma mostly polished, mesoscutum lightly and minutely punctate (Fig. 11F), punctures very sparse elsewhere on mesosoma; prescutal sutures short, extending shortly beyond anterior level of tegula; episternal sulcus simple (Fig. 13F); mesopleural suture narrowly foveolate (Fig. 12F); propodeal enclosure with several pairs of longitudinal carinae; propodeum (Fig. 14F) polished and impunctate posteriorly and laterally, coarse reticulations restricted to marginal ridge along transition between posterior and lateral surfaces. Hind tibia with longitudinal cluster of dark denticles dorsobasally (Fig. 18K). Petiole subcylindrical, T1 relatively low (Fig. 5F). Pygidial plate narrow, delineated by distinct posteriorly parallel carinae (Fig. 16F). Fore wing (Fig. 19L) with first recurrent vein more or less interstitial with first and second submarginal cells, second recurrent vein meeting third submarginal cell at about one-eighth of cell length from base.

Head black with silvery appressed pubescence (Figs 7F, 9F); antenna with scape, pedicel and base of flagellum ventrally yellow, dorsum and terminal segments of flagellum black; mandible yellow with black tip. Mesosoma and legs mostly yellow, hind legs reddish from trochanter to tarsus, amount of black coloration on mesosoma varying from almost entirely absent with only black marks on scutellar groove and mesosternum (including base of mesopleuron) remaining to slightly more extensive than in male with black marks also present anteroventrally on epicnemium, on lower half of metapleuron, and over entire propodeal enclosure. Petiole basally yellow, becoming reddish apically; remainder of metasoma reddish.

Etymology.

From the Latin for ‘pale’, in reference to this species’ distinctive coloration.

Notes.

Because of its marked differences with other known lightly coloured Psenulus we have concluded that this is a new species. We have collected females that show a great deal of discoloration and are even paler than the holotype, with hardly any black at all, save for a reduced band at intersection of the mesoscutum and scutum (Fig. 22B) and the head (Fig. 22A, B).

This species has been consistently collected at Mang Kung, the site with the highest anthropogenic disturbance, and was also found in mangroves (13.6% occurrence). It has the second longest (after P. continentis) recorded activity period, spanning from March (W10) to December (W50).