Zethus taiwanus, Lu, 2017

Lu, Sheng-Shan, 2017, New record of the genus Zethus Fabricius from Taiwan, with the description of Z. taiwanus sp. nov. and a key to the species of trimaculatus - group (Hymenoptera: Vespidae: Eumeninae), Zootaxa 4324 (3), pp. 529-540 : 533-536

Zethus taiwanus sp. nov. Yeh & Lu

( Figs. 7–15 , 21, 23, 25 & 26)

Material examined. All types except one male were collected by WCY from Guishan , Xindian District , New Taipei City, E24°53'6.01" N121°34'19.59", a. s. l. 500m. Holotype: ♀, V/25/2012 . Paratypes: 1♂, V/23/2012; 1♂ 1♀, V/25/2012; 6♂, V/14/2013; 1♀, V/25/2013. 1♂, V/19/2010, Machia, a.s.l. 180m, Pingdong County, leg. I. H. Sung.

Holotype and most of paratypes to be deposited at the Forest Arthropoda Collection Taiwan ( FACT), TFRI. The pair collected in V/25/2012 will be donated to the National Museum of Natural History , Taichung .

Diagnosis. Bi-coloured species with black body and yellowish brown legs. Female clypeus minutely tridentate, male clypeus strongly bi-dentate with apical notch deep and 1/5 as wide as clypeus. Male mandible with three large teeth, basal tooth formed a rectangular plate with basal angle of mandible and separated from middle tooth by a broad notch. Female ocelli small with OD distinctly shorter than the radius of antennal socket. Aedeagus of male genitalia with ventral lobe of penile valve erect and thin, cockscomb-shaped in profile, basal plate triangular with attenuate and pointed apex.

Holotype (female, Fig. 15 )

Structure. Head: Clypeus gently convex, transversely oblong and slightly less than two time as wide as long, apex widely truncate with three blunt teeth, middle tooth smaller and indistinct, apical truncation about 1/3 as wide as clypeus (fig. 7). Antennal scapes broadened toward apex and slightly shorter than mandibles, inter-antennal area gently raised. Ocelli small with OD distinctly smaller than the radius of antennal socket, ocellar area not raised. Gena distinctly wider above than below in profile, postero-ventral corner strongly angulate, broadest part distinctly wider than upper part of compound eye ( Fig. 10 ). Occiput carina strong and complete, distinctly ridge-like and bordered anteriorly with one row of short pits. Mandible with three blunt teeth, basal one small and indistinct; out surface of mandibles with irregular longitudinal depressions and ridges, basal part shallowly macropunctate.

Mesosoma: Anterior margin of pronotum straight, humeral angle distinctly angulate, pronotal lamella strong laterally and weak dorsally. Subhumeral area moderately depressed. Notaulix complete and straight, broad and deep apically and slightly attenuate toward base. Tegula as in Z. trimaculatus but more elongate, with posterior lobe distinctly longer than half length of anterior part ( Fig. 9 ). Mesopleura with medial part gently convex, pleural suture defined by a row of large, deep and transversely elongate pits, epipleural suture discernible only by depressed line of punctures. Scutellum rectangular with a weak medial longitudinal furrow, anterior margin adorned with a transverse row of six large pits. Metanotum rectangular with postero-lateral corners angulate, posterior side vertical. Posterior depression of propodeum broadly concave with interspaces of rugose punctation tend to from transverse ridges, median ridge strong and raised, dorsal propodeal aperture elliptical; dorsal side of propodeum slightly inclined outward and separated from lateral side by indistinct lateral carina; submedian carina distinct at anterior half, invisible posteriorly. Propodeal lamella well developed and strongly protruding upward ( Fig. 14 ); propodeal valvula rectangular and well segregated from propodeal lamella. Hind tibia with only three or four irregularly spaced short spines on posterior side.

Metasoma: T2, T3 and S2 with smooth and shining apical lamella, weak on S2 and well developed and protruding posteriorly on T2 and T3, apical lamella of T3 two times as long as that of T2. T1 a little shorter than T2, dorsal margin smoothly curved between basal stem and apical expansion; apical expansion elliptical in dorsal view with lateral sides smoothly curved, dorsal side with a straight and weak dorsal ridge. Dorsal side of T1 less depressed sub-apically than in Z. trimaculatus , apical margin weakly swollen, smooth and shining. Ventral side of T1 and S1 as in Z. trimaculatus ( Fig. 11 ). Second metasomal segment sessile, distinctly longer than wide, smoothly and gently curved both dorsally and ventrally. T2 & T3 slightly depressed sub-apically, S3 gently and broadly protruding posteriorly, apical margin with thin and smooth flange.

Integumental sculptures. Foveate to reticulate macropunctures densely present on head, dorsal side of pronotum except its median narrow area, basal 1/3 of scutum, upper half of mesopleura and T1, sparser and shallower on posterior half of gena, scutellum and metanotum. Clypeus densely and shallowly foveate, antennal scape smooth ventrally and obscurely micropunctate dorsally. Subhumeral area broadly and transversely sulcate, scutal area between notaulix smooth with sparse and shallow macropunctures, tegula smooth. Mesopleura moderately and shallowly macropunctate below pleural and epipleural sutures with epicnemium and posterior part coriaceous. Propodeum coriaceous on dorsal and lateral sides, obscurely macropunctate along upper margin of lateral side; posterior depression with upper 1/3 rugose and lower 2/3 obscurely sulcate. T1 with VFB coarsely foveate but smooth close to inner margin, S1 with BS foveate and AE obscurely rugose. T2 sparsely micropunctate, T3 coriaceous with sub-apical depressed area moderately macropunctate dorsally and deeply and densely macropunctate laterally, S3 densely macropunctate.

Body markings. Body black, legs mainly yellowish brown with dark brownish femora. A yellow spot on dorso-inner margin of antennal socket, a tiny and faint pale spot on gena above. A pair of transverse yellow lateral spots on apical margin of T1. Tegula yellowish brown. Wings transparent, very palely enfumed with brown.

Pilosity. Long yellowish brown hairs (more than three times of OD) present moderately on entire body except antennal flagella, very dense on clypeus and shorter on scutum. Hind tibia with dense and yellowish pubescence on inner side.

Male. General morphology of male is similar to the holotype female, differences are noted as follows: Ocelli larger, OD about as wide as the radius of antennal socket. Clypeus strongly bi-dentate, with apical notch deep and broad, about 1/5 as wide as clypeus; foveate punctures of clypeus deeper. Mandible with three large teeth, basal tooth shorter and blunt, formed a rectangular plate with basal angle of mandible and separated from middle tooth by a deep and broad notch, middle tooth close to and forming a fork with apical tooth ( Fig. 8 ); base of mandible usually with a transverse yellow mark (absent in one male). Antenna as in holotype female ( Fig. 13 ), FXI conical, distinctly longer than FX, roundly obtuse at apex and coloured yellowish brown to dark brown ( Fig. 12 ). Humeral angle more strongly angulate, anterior margin of scutellum adorned with a row of eight large pits in two males. Submedian carina of propodeum weak. Legs nearly wholly yellowish brown in six of nine males, dark brown in the other three.

Genitalia (Figs. 21, 23, 25 & 26): Ventral lobe of gonocoxite protruding and horn-like, basal lobe of volsellar ridge horn-like and slightly curved apically, ventral root of digitus long, straight and pointed. Volsella adorned with dense and long hairs on cuspis and digitus, short hairs on middle part adjacent to digitus and short setae on volsellar ridges. Cuspis sub-triangular in shape with a pack of about 13 dark teeth of variable size close to ventral margin and some denticles on medial lobe. Basal lobe of digitus deeply curved and saddle-like with many denticles along dorsal margin of its outer side opposed to denticles on median lobe of cuspis. Distal lobe of digitus ribbon-like, attenuate toward apex and slightly twisted (23). In lateral view, aedeagus with ventral lobe of penile valve erect and basally curved angularly and basal apodeme strongly curved at middle (Fig. 25); basal plate of aedeagus triangular with attenuate and pointed apex (Fig. 26).

Variations of paratype females. No distinct differences were discovered between the holotype and the two paratype females.

Measurements (in mm). ♀ BL 13.8–14.8, FWL 7.5–8.8. ♂ BL 11.4–13.6, FWL 7.5–10.8.

Etymology. This species is named after its type locality in Taiwan.

Remarks. The site where the specimens of Z. taiwanus were collected from Guishan is located at the margin of secondary forest close to the agricultural fields of villagers. The collecting site in Machia is a recreational park partly surrounded nearby also by secondary forest. This species is probably very rare, as a three-year survey of eumenine fauna of Taiwan conducted between 2012–2014 did not yield other additional records.

Figures

FIGURES 7 – 15. Zethus taiwanus sp. nov. 7, female clypeus; 8, male clypeus 9, left tegula, dorsal; 10, head, lateral; 11, metasomal petiole, ventral; 12, apex of male antenna, ventral; 13, male antenna, lateral; 14, propodeum, lateral; 15, female habitus, lateral. AE, apical expansion of S 1. BS, basal stem of S 1. VFB, ventral flat bottom of T 1.