Xyela exilicornis Maa, 1949

Blank, Stephan M., Shinohara, Akihiko & Altenhofer, Ewald, 2013, <strong> The Eurasian species of <em> Xyela </ em> (Hymenoptera, Xyelidae): taxonomy, host plants and distribution </ strong>, Zootaxa 3629 (1), pp. 1-106 : 31-33

Xyela exilicornis Maa, 1949

Xyela exilicornis Maa 1949: 30–32 , ♂, type locality: China, Fujian Sheng, Shaowu, Wuku .

Description. Female. Color. Head yellow with brown and black pattern: face predominantly pale brown leaving small stripe along eye and on vertex yellow, two diffuse black stripes along frontal furrows meeting black ocellar and postocellar area, black longitudinal spot in middle of frons present; kidney-shaped spots on vertex separate from black postocellar area. Antenna pale brown. Thorax dorsally brown with more or less yellow pattern on pronotum, mesonotal lobes and mesoscutellum, tegulae pale, mesepisternum largely pale brown. Abdominal terga brown, lateral parts of terga 8 and 9+10 paler, valvifer 2 completely pale brown, membrane between valvifer 2 and valvula 3 white, valvula 3 brown (darker than valvifer 2). Legs pale brown, posterior coxae dark brown with distal 0.3–0.5 pale. Wing membrane slightly infuscate, venation and pterostigma pale brown.

Morphology. Fore wing 4.0– 4.3 mm long, 1.95–2.05 times longer than ovipositor sheath, vein Rs+M 125–150 µm long, 2r-m meeting Rs proximal to furcation of Rs1 and Rs2. Synantennomere 3 640–760 µm long, antennomere 4 130–150 µm long and 4.0–5.0 times longer than wide distally. Article 3 of maxillary palp 440–480 µm long, 1.35–1.50 times longer than scape and about as wide as synantennomere 3. OOL: POL = 1.70–1.90: 1. Ovipositor sheath 2.0– 2.1 mm long, valvula 3 1.70–1.80 times longer than valvifer 2 and 6.5–7.0 times longer than wide at base. Valvula 3 of ovipositor strongly compressed in cross section, pale membranous area along ventral edge of valvula 2 about as long as width of valvula 3 at base, dorsal edge of valvula 3 sloping down to round tip in distal fifth, valvula 3 with sensilla field exposed and directed caudally, bearing 8 setae. Ovipositor bent downwards. Valvula 1 compressed, aulax terminating preapically, small preapical tooth of dorsal edge present, dorsal edge sloping down and ventral edge sloping up to tip, with ca 13 oblique closely spaced annuli in distal 0.2, without serrulae, olistether with ca 7 setae. Left and right valvulae 2 fused along dorsal edge up to distal 0.1, dorsal margin almost smooth, distal 0.1 abruptly narrowing to tip. Valvula 1 in distal third with 10 almost vertical annuli, slightly proximal to annuli groups of 2 sensilla campaniformia enclosed by an indistinct sclerotization. Posterior tibia 0.9–1.0 mm long, all claws with delicate subapical tooth.

Male. Color. Head yellow with pale and dark brown pattern: ocellar and postocellar area and kidney-shaped spots dark, frons pale or indistinctly diffuse pale brown (faded holotype possibly with brown stripes along supraantennal furrows and dark longitudinal stripe in middle of frons, male from Hong Kong without indication of dark pattern on frons). Antennae pale brown. Thorax dorsally brown with distinct pale pattern on pronotum, mesonotal lobes and mesoscutellum, tegulae pale, mesepisternum largely pale brown. Abdominal terga brown, sterna possibly paler than terga (faded?), hypopygium completely pale. Legs including posterior coxae pale brown (faded?). Wings slightly infuscate, venation and pterostigma pale brown.

Morphology. Fore wing ca 3.4 mm long, Rs+M 50–90 µm long, 2r-m meeting Rs proximal to furcation of Rs1 and Rs2. Synantennomere 3 740–790 µm long, antennomere 4 210–220 µm long and ca 7.0 times longer than wide distally. Article 3 of maxillary palp ca 450 µm long, ca 1.45 times longer than scape and about as wide as synantennomere 3. OOL: POL = 1.60–1.90: 1. Longitudinal apodeme of basiparamere curved, basal portion in lateral position, harpe ca 1.3 times longer than wide distally in lateral view. Lower ergot on valvular stalk small but evident. Valviceps 1.50–1.65 times longer than wide on medial lobe, lateral lamella vertical with proximal edge convex and distal base concave, proximal lobe of penis valve ca 0.21–0.22 times as long as valviceps and 0.90–0.95 times as high as medial lobe, excision on lower edge triangularly shaped and 0.30–0.33 as deep as width of medial lobe, valviceps on medial lobe ca 1.17 times wider than on distal lobe, 2 distal flagella present, tip of longer flagellum reaching 0.95–1.00 width of distal lobe ( Fig. 137 ). Valviceps with distinct median longitudinal sclerotization absent (indistinct shadow present), medial lobe broad and slightly rounded on upper edge, with 5–9 cone-like sensilla on proximal portion of medial lobe, upper edge between medial and distal lobe with numerous setae. Posterior tibia 0.90–0.95 mm long, all claws with delicate subapical tooth.

Type material. Holotype ♂: “Wuku [...; 2 Chinese characters for Wuku], Shaowu, Fukien, 400 m, 15.iii.1945, K. S. Lin (indoor)”; [pink with a red edge:] “ Xyela exilicornis sp. n. Holotype ♂ T. Maa, 1948”; “ Xyela exilicornis Maa, 1949 det. S. M. Blank 2001”. Specimen partly covered by mould and psocopteran excrement, antennomeres 4–12, right fore wing and right hind leg missing. Apparently faded since time of original description, because the dark color is pale brown (e.g., abdomen) and pale color of body is brownish yellow (e.g., most of face). Genitalia glued to piece of cardboard and stored on pin of holotype. TARI.

Host plant.? Pinus massoniana Lamb.

Geographic distribution. China (Fujian Province, Xianggang) ( Fig. 12 ).

Remarks. The ovipositor is longer than that of the similarly colored Xyela curva . The penis valve is triangularly excised, similar to that of X. japonica and X. occidentalis , but the latter two species have a dark head.

A “punctuation” of the body surface as mentioned in Maa’s original description of X. exilicornis is not present, but the holotype exhibits coriaceous microsculpture as is typical for Xyela . The color of the holotype specimen is possibly strongly modified. The dark pattern may have become paler and the yellow pattern partly pale brown. Also 2 of the 3 studied females from Hong Kong are possibly faded, and the above description of the color pattern in female sex is taken from the third, dark specimen. The pale females have the dark pattern generally pale brown. Their face is predominantly pale brown, and they lack the dark stripes along the frontal furrows and the dark medial spot of frons.

Maa (1949) emphasized that X. exilicornis “is only comparable to X. kamtshatica Guss. (Kamtshatka) in its wing venation”, and accordingly, Rasnitsyn (1965) placed it in the alpigena group. The presence of a vertical lateral lamella on the penis valve with a concave excision and the proximal lobe of the valviceps not protruding above the medial lobe refer it to the X. curva group.

The hitherto unknown female was associated with the help of material collected in Hong Kong on the same site and period of time. Xyela exilicornis was found there together with X. sinicola .

Pinus massoniana is supposed to be the host plant, because it is the only pine species whose native geographical and altitudinal distribution range coincides with the known collection records of X. exilicornis ( Mirov 1967; see also X. sinicola ). Among the material of both species 4 specimens are labeled as being collected on “ 10.V.1965 ” and 6 on different days of “[...]. II.1965 ”. The date May is regarded as a type error for February, because blooming of P. massoniana in February is more likely due to the rather southern geographical position of the collection locality Hong Kong.

Figures

FIGURE 12. Records of Chinese and Taiwanese Xyela species, X. exilicornis (5 specimens from 2 collection sites), X. meridionalis (4 specimens from 1 collection site) and X. sinicola (10 specimens from 4 collection sites), and natural distribution of their supposed host plants, Pinus massoniana (solid line, according to Kindel (1995) and P. morrisonicola (dashed line, according to Mirov 1967).

FIGURES 136–145. Penis valves of Xyela species: X. curva group, X. julii group (part). Figs 138–139 and 141 reproduced from Blank et al. (2005).