Lithosaphonecrus mindatus Ide, Aung & Tanaka, 2020

Ide, Tatsuya, Aung, Mu Mu & Tanaka, Nobuyuki, 2020, First record of Cynipidae from Myanmar with description of a new species of Lithosaphonecrus (Hymenoptera: Cynipidae: Synergini), Zootaxa 4810 (2), pp. 344-350 : 345-348

Lithosaphonecrus mindatus Ide, Aung & Tanaka , sp. nov.

( Figs. 1–13 )

urn:lsid:zoobank.org:act:78DF0272-2B0C-468E-9CE9-6C1A9D2483AB

Material examined. Holotype (designated here): 1 adult female, about 20km west from Mindat, Chin State, Myanmar, 21°23'36.25"N, 93°46'45.03"E, elevation about 2,400m; collection of gall: 28.xi.2017, emergence of adult: 2.xii.2017; T. Ide leg.; deposited in National Museum of Nature and Science, Tokyo, Japan ( NSMT) with accession number NSMT-I-Hym 77508.

Description. Head and mesosoma black; antenna brown, except for darker terminal flagellomere; palpi yellow; mandible brown, except for darker margin; tegula yellow; legs yellow, except for darker metacoxa and tarsal claws. Metasoma mostly dark and ventrally reddish brown; hypopygial spine yellow.

Head ( Figs. 1–4 ) rounded in frontal view, almost as broad as mesosoma in dorsal view. Vertex and occiput coriarious; occipital carina only present laterally, posterior of the genae. Median ocellus transversely oblong; lateral ocellus round; POL:OOL:LOL = 20:11:10. Frons coriarious with delicate longitudinal strigae from antennal rims. Diameter of antennal rim 3.0 times as broad as distance between inner margins of rims, almost as broad as distance between lateral margin of antennal rim and inner margin of compound eye. Inner margin of compound eye concave; distance between inner margins of compound eyes 1.1 times as broad as height of compound eye. Lower face including malar area and clypeus covered with setae, with facial strigae radiating from ventral margin of clypeus; facial strigae reaching beyond area between antennal rim and compound eye and partly connecting to longitudinal strigae on frons; anterior tentorial pit small; subocular impression absent; epistomal sulcus and clypeo-pleurostomal line indistinct; ventral margin of clypeus almost straight. Gena coriarious, not broadened behind compound eye. Antenna ( Fig. 10 ) 13-segmented; scape excluding base 1.4 times as long as pedicel, almost as long as first flagellomere; relative lengths of flagellomeres 1–11: 18, 9, 10, 11, 13, 14, 15, 16, 16, 15, 30.

Mesosoma ( Figs. 5–7 ) slightly longer than high in lateral view. Pronotum rugose, covered with setae; submarginal pronotal impression narrow, marked by ledge posteriorly; pronotal plate smooth, distinctly set off, with anterolateral corners, ventral and lateral margin marked; lateral pronotal carina present but indistinct. Mesoscutum slightly broader than long in dorsal view, coriarious with broad transverse rugae, covered with sparse setae, except for anterior area transversely rugulose, covered with dense setae; impression mesad parascutal carina anteriorly continuing to anterior end of notaulus; notaulus complete but frequently separated by parallel rugae; anteroadmedian signum absent; parapsidal signum present but indistinct; median mesoscutal impression present posteriorly as short triangle impression. Dorsal axillar area coriarious. Mesoscutellum coriarious but rugose toward margins, covered with sparse setae; scutellar fovea with longitudinal carinae, separated by broad foveal septum; posterolateral margin of scutellar fovea indistinct with posterior rugae. Mesopleuron coriarious with parallel longitudinal strigae; mesopleural triangle covered with dense setae; ventral border of mesopleural triangle marked throughout by distinct ventral carina. Metascutellum subrectangular; metanotal trough with vertical carinae, with setae. Metepimeron marked by distinct ledge posteriorly. Propodeum ( Fig. 7 ) smooth, covered with short setae; lateral propodeal carina broad, parallel to another side.

Marginal cell of forewing ( Fig. 11 ) open, 3.2 times as long as broad. R1 and Rs not reaching wing margin. Areolet absent. Rs+M indistinct. Apex of metatarsal claw distinctly bent; base not expanded to lobe. Length of forewing 2.03 mm, and of hind tibia 0.57 mm.

Metasoma ( Figs. 8, 9 ) smooth; metasomal terga II and III fused, with sparse setae basolaterally, with band of rows of minute punctures posteriorly. Subsequent terga and hypopygium with band of minute punctures. Lateral flap of hypopygium rounded in lateral view; projecting part of hypopygial spine only slightly protruded in lateral view, tapered to apex in ventral view, 1.6 times as long as high in lateral view, 1.3 times as long as wide in ventral view; subapical setae sparse, slightly reaching beyond apex of spine.

Diagnosis. The new species resembles L. arcoverticus Liu, Zhu & Pang more closely than other congeners, sharing the following morphological features: 1) veins of R1 and Rs of the forewing do not reach the wing margin ( Fig. 11 ); 2) the surface of the metanotal trough has longitudinal carinae ( Fig. 7 ); and 3) F1 is at least 2.0 times as long as F2, F3–F10 gradually elongate apically, and F11 is 2.0 times as long as F10 ( Figs. 1 , 10 ). However, the new species is differentiated from L. arcoverticus by the following morphological features: 1) the scutellar fovea of the mesoscutellum is separated by a broad foveal septum in the new species ( Fig. 6 ), but by a narrow carina in the latter; 2) the anteroadmedian signum is absent in the new species ( Fig. 6 ), but present in the latter; and 3) the median mesoscutal impression is present as short triangular impression in the new species ( Fig. 6 ), but present in the posterior one fourth of the mesoscutum in the latter. The syntergite (metasomal terga II + III) does not cover the remaining tergites in the holotype of the new species ( Fig. 8 ), but we do not include this in the diagnosis because this might be due to sample preparation.

Geographic distribution. Chin State, Myanmar.

Biology. An adult female emerged from a bud gall induced on Lithocarpus thomsonii on December 2, 2017 ( Figs. 12–13 ). Several exit holes were observed on the surface of the gall at collection. The gall is almost sphereshaped, being 10.2 mm in diameter.

Etymology. The specific epithet is derived from the type locality, Mindat Township, located on the northeastern side of Mt. Victoria (Natma Taung), the highest peak of the Chin Hills in northwestern Myanmar.

DNA Barcoding. Pairwise distances among available COI sequences of Lithosaphonecrus species are shown in Table 1. The sequence of the new species shows a 14–15% difference from congeners based on 614 bp of the COI region.

Notes. Most of the morphological characteristics and molecular data support the treatment of the new species as Lithosaphonecrus . However, the following morphological characteristics are inconsistent with the diagnosis of this genus by Bozsó et al. (2013): 1) F1 of the female antenna is 2.0 times as long as F2 (not 1.5–1.9 times as long as F2 as in the diagnosis); and 2) the foveal septum is broad (not absent or indistinct as in the diagnosis). These inconsistencies are found in other Lithosaphonecrus species: F1 is 2.1 times as long as F 2 in L. arcoverticus ( Yang et al. 2019) and the foveal septum is broad in L. vietnamensis ( Abe et al. 2014) . Therefore, the diagnosis of the genus Lithosaphonecrus should be broadened to include these characteristics.

The life history of the new species is mostly unknown. As a genus of the inquiline tribe Synergini , Lithosaphonecrus species were treated as inquilines by Bozsó et al. (2013). In fact, an unidentified Lithosaphonecrus species was observed to lay its eggs in a developing host gall (Fig. 67 in Bozsó et al., 2013). However, the inducer of the host gall of each Lithosaphonecrus species has never been confirmed ( Bozsó et al. 2013; Yang et al. 2019; Pujade-Villar et al. 2020). Yang et al. (2019) suspected that this genus contains both inquilines and gall inducers, mainly based on the observation that two Lithosaphonecrus species, L. arcoverticus and L. decarinatus Liu, Zhu, & Pang , and one Saphonecrus species emerged from the same kind of gall, and no other candidate gall inducers, except for a few parasitic chalcidoid wasps, were collected from the gall, despite the large numbers of galls collected in long-termed sampling. Since Synergus itoensis Abe, Ide & Wachi is a known gall inducer within Synergini ( Abe et al. 2011) , the possibility that the Lithosaphonecrus species may be a primary gall inducer should be considered in further studies of the biology of these species. Faunal studies of cynipid inquilines and gall inducers throughout the distribution of Lithocarpus will provide essential information to understand their biology.

Lithosaphonecrus mindatus sp. nov. is the first record of Cynipidae from Myanmar. In Myanmar, which has a distinct north-south polarity from lat. 35° N to lat. 10° N, and where elevation ranges from 0–5,881 m, there are species-rich forests of Quercus , Castanopsis , and Lithocarpus ( Kress et al. 2003) , suggesting potentially high cynipid diversity in Myanmar.

Figures

FIGURES 1–9. Holotype female of Lithosaphonecrus mindatus sp. nov.: 1 head, frontal view (scale bar = 100 μm); 2 surface sculpture of frons (scale bar = 50 μm); 3 head, lateral view (scale bar = 100 μm); 4 head, dorsal view (scale bar = 100μm); 5 mesosoma, lateral view (scale bar = 100μm); 6 mesosoma, dorsal view (scale bar = 100 μm); 7 propodeum, dorsal view (scale bar = 100 μm); 8 metasoma, lateral view (scale bar = 200 μm); 9 surface sculpture of posterior area of metasomal terga (scale bar = 50 μm).

FIGURES 10–11. Holotype female of Lithosaphonecrus mindatus sp. nov.: 10 antenna, (scale bar = 100 μm); 11 forewing (scale bar = 1 mm).

FIGURES 12–13. 12 Bud gall from which Lithosaphonecrus mindatus sp. nov. emerged (scale bar = 1 cm); 13 holotype female of Lithosaphonecrus mindatus sp. nov., habitus (scale bar = 1 mm).