Megalotomus angulus ( Hsiao, 1965 ) Yi & Wang & Zhang & Bu, 2022

Yi, Wenbo, Wang, Shijun, Zhang, Hufang & Bu, Wenjun, 2022, Notes on Megalotomus Fieber, 1860 in the Palaearctic Region (Hemiptera, Heteroptera, Alydidae), Zootaxa 5128 (2), pp. 211-224 : 212-215

Megalotomus angulus ( Hsiao, 1965) NEW COMBINATION

( Figs. 1–6 , 23–25 )

Alydus angulus Hsiao, 1965: 430 , 434. Holotype: ♂, China (Southwest), Sichuan, Xiaojin County, 2350m; NKUM. Hsiao, 1977: 271; Ren, 1992: 144–145; Dolling, 2006: 38.

Megalotomus obtusus Ghauri, 1972: 285–287 . Holotype: ♂, Pakistan (West), Shangla ; BMNH. New subjective synonym.

Diagnosis. Differs from other related species by the following combination of characters: smaller size (body length less than 12 mm); body from yellowish or reddish brown to brownish black ( Figs. 1–3, 5 ); antennal segments I and II subequal in length, or segment I slightly longer than II; pronotum with a prominent black and hairless portion medially, cuneiform and beloid ( Figs. 1 and 5 ); posterolateral angle of pronotum evaginate, but never pointed ( Figs. 1 and 5 ); surcapsular spines of genital capsule never cross over each other, and lack any projection ( Fig. 23 ); the terminal half of each paramere bifurcated into two lobes, with the inner lobe shorter, acute, and spinose, and the other longer, elongate, and strongly curved ( Figs. 24 and 25 ).

Redescription. Body ( Figs. 1–3, 5 ) relatively small, elongate, with length from 10.0 to 12.0 mm, about 5 times as long as width across the eyes. Body surface and vestiture. Body primarily brownish black; dorsum of head with a yellowish stripe longitudinally located on midline of clypeus, cephalic vertex with two symmetric yellowish maculae posterior to antennal bases, one short longitudinal yellowish brown stripe between ocelli, two symmetric yellowish maculae posterolateral to head (sometimes invisible if covered by collar of pronotum), basal parts of antennal segments I–III yellowish with brownish tips; pronotum with a prominent dark black and hairless region, triangular or cuneiform, conspicuously beloid, occupying approximately over half the area of the pronotum, edge of posterolateral angle of pronotum pale brown, posterior apex of scutellum yellowish, middle of posterior part of mesosternum yellowish, peritreme of metathoracic scent gland yellowish, corium of forewing pale brown, with small and inconspicuous yellowish macula near apex of posterior wing cell of corium, tibiae yellowish in middle and brownish at both ends, tarsus segment I yellowish at basal parts; middle of anterior of abdominal sterna with a longitudinal yellow stripe slightly surpassing anterior rim of segment IV, abdominal pleuron yellow at anterior half of segments V–VII. Body surface with dense, silver, semi-erect setae, and inconspicuous punctures. Head and cephalic appendages. Head triangular, length slightly shorter than width across the eyes; eyes prominent, projecting over cephalic vertex in lateral view; ocelli protruding, anterior margins of ocelli in line with posterior margins of eyes, interocellar distance slightly shorter than distance between ocellus and ipsilateral eye, interocellar distance also slightly shorter than or equal to the distance between two symmetric yellowish maculae on cephalic vertex; anterior margin of clypeus surpassing apices of paraclypeae (mandibular plates); antennal segments I–III straight, with segment I slightly longer than or equal to segments II and III, and segment IV longest, elongate fusiform and slightly curved; labium reaching about middle of meso-coxae, with segment I and II subequal in length, longer than segments III or IV, and segment III shortest. Thorax and thoracic appendages. Pronotum trapezoid in dorsal view, declined forward, with posterior margin of pronotum slightly wider than head through eyes, posterolateral angle of pronotum slightly upward and subacute, but not with sharply pointed apex; scutellum about 1.2–1.4 times as long as its basal width, with inconspicuous transverse wrinkles, and apex scarcely upturned; forewings conspicuously surpassing abdomen posteriorly, with anterior margin of forewing slightly constricted in the middle of costa; femora shorter than tibiae, meta-femora with 5–8 spines on inner surface of the terminal half, among them, 4–5 distinct and gradually longer from proximal to terminal, others (if existing) small and uniform, and always alternate ranking with long ones; tarsi long, with segment I twice as long as segments II and III together. Pregenital abdomen. Abdomen elongate, more slender than pronotum, approximately cylindrical, and contracted basally; female abdominal sternite VII split longitudinally in the middle, from the posterior margin to the median half. External genitalia ( Figs. 23–25 ). Genital capsule with a pair of symmetric surcapsular spines, never crossed; parameres slender and strongly curved, each one bifurcated into two terminal lobes, with inner lobe shorter and ending in a spine, and outer lobe longer but not apically pointed.

Measurements (in mm). Male (n=5). Body length 10.7–11.4; length of head 1.9–2.1, width across eyes 2.1– 2.3; length of antennal segments (I) 1.5–1.6 (II) 1.4–1.5 (III) 1.3–1.4 (IV) 3.2–3.4; length of labial segments (I) 1.1–1.2 (II) 1.0–1.1 (III) 0.5–0.6 (IV) 0.8–0.9; median length of pronotum 1.9–2.1, humeral width 2.1–2.2; scutellar length 1.1–1.2, width 0.9–1.0. Female (n=5). Body length 11.3–11.7; length of head 1.9–2.1, width across eyes 2.1–2.3; length of antennal segments (I) 1.5–1.6 (II) 1.4–1.5 (III) 1.6–1.7 (IV) 2.9–3.1; length of labial segments (I) 1.2–1.3 (II) 1.2–1.3 (III) 0.4–0.5 (IV) 0.8–0.9; median length of pronotum 2.0–2.2, humeral width 2.4–2.6; scutellar length 1.3–1.4, width 0.9–1.0.

Material examined. Type material. Holotype ( Figs. 1–4 ), ♂, China, Sichuan Province, Xiaojin County, Xinjie Village , 2350 m, 24-August-1963, Huanguang Zou leg. ( NKUM); Allotype, ♀, ibid ; Paratypes, 1 ♂, 1 ♀, ibid .

Other specimens. China, Gansu Province: 1 ♀, Yongdeng County, Liancheng , August-1973, Nan Lv leg. ; Hebei Province: 1 ♂, 2 ♀♀, Xinglong County, Wulingshan National Nature Reserve , 1700 m, 22-June-1995, Leyi Zheng leg. ; 1 ♀, same locality, 1200 m, 26-June-1995, Wenjun Bu leg. ; Inner Mongolia: 1 ♂, Alxa League, Helanshan National Nature Reserve, Halawu Management Station , Qianggangling , 1861 m, 8-August-2010, Ying Cui leg. ; 1 ♀, Alxa League, Helanshan National Nature Reserve, Gulaben Management Station , Luanchaigou , 2285-2375 m, 6-August-2010, Haixin Tang leg. ; Shaanxi Province: 1 ♀, Ningshan County, Huoditang , 1640 m, 14-August-1994, Wenjun Bu leg. ; Shanxi Province: 1 ♂, Gaosheng, Yunmengshan , 16-September-1974, collector unknown ; 1 ♂, Xinzhou City, Ningwu County, Luyashan National Nature Reserve , Chedaogou , 1700 m, 22-July-2011, Kai Dang leg. ; 1 ♂, Xinzhou City, Wutai County, Taihuai Town , Wutaishan National Nature Reserve , Xinyinsi Temple , 39.01°N, 113.63°E, 1844 m, 13-August-2020, Wenbo Yi leg. ( XZTU) ; Sichuan Province: 1 ♂, Xiaojin County, Xinjie , 2350 m, 25-August-1963, Jiang Xiong leg. ; 1 ♂, 2 ♀♀, same locality, 24-August-1963, Huanguang Zou leg. ; 1 ♂, Baoxing County, 2200–2700 m, 27-July-1963, Huanguang Zou leg. ; 1 ♂, Hechuan District (now in Chongqing), Chengguan , 2000–2300 m, 9-September-1963, Huanguang Zou leg. ; 1 ♂, Barkam , 2600–2800 m, 11-August-1963, Huanguang Zou leg. ; 1 ♂, 1 ♀, Ruoergai County, Dazha Temple , 3300 m, 29-July-1963, Leyi Zheng leg. ; Tibet: 1 ♂, 1 ♀, Zayu County, south of Zibagou , 2667 m, 8-July-2013, Wenbo Yi leg. ; 1 ♀, Nyingchi County, Bayi Town , 3000 m, 6-August-1963, Huaijun Xue & Xinpu Wang leg. ; Yunnan Province: 1 ♂, Dali Bai Autonomous Prefecture, Cangshan , 2225 m, 25-May-2009, Min Li leg. ; 1 ♂, Lijiang City , 11-August-1979, Guoqing Liu leg. ; 1 ♀, Wuding County, Shizishan , 11-August-1986, Liu leg. ; 1 ♀, Kunming City , 25-June-1989, collector unknown ; 1 ♀, Yulong Mountain , 2700 m, 11-August-1979, Liu leg. ; 1 ♀, Mangshi , 24-August-1979, Huanguang Zou leg. ; 1 ♀, Baoshan City, Taibaoshan , 20-August-1974, Huanguang Zou leg. (All above specimens housed in NKUM if not specified.).

Distribution. China (Gansu, Hebei, Inner Mongolia, Shaanxi, Shanxi, Sichuan, Tibet, Yunnan), Pakistan. ( Fig. 7 )

Remarks. The type material of M. angulus ( Hsiao, 1965) comb. nov. along with other materials were rechecked and re-measured during the study. The following features were identified, which are shared with species in the genus Megalotomus rather than Alydus : antennal segment I slightly longer than segment II, or both segments equal in length; posterolateral angles of the pronotum upward and pointed; surcapsular spines on the genital capsule not crossed, with parameres strongly curved and bifurcated; and female abdominal sternite VII split. The above features indicate M. angulus ( Hsiao, 1965) comb. nov. should be placed in the genus Megalotomus . As a result, the new combination is herein proposed. In addition, the holotype of Megalotomus obtusus Ghauri, 1972 deposited in BMNH was also examined and photographed ( Figs. 5 and 6 ). Megalotomus obtusus resembles M. angulus ( Hsiao, 1965) comb. nov. in diagnostic features, as also mentioned in the original description on page 285 and illustrations on page 286 in Ghauri (1972), such as the “hind femur with five spines…; paramere bifurcate…, etc.”. All above characters were confirmed. Although M. obtusus is reported as endemic to Pakistan and M. angulus to China, this may be due to the limited number of specimens and lack of published data, and it is therefore easy to consider the two nominal species as synonymous when considering the same Palaearctic distribution and the identical characters shared by both.

The host plant and the biology of M. angulus ( Hsiao, 1965) comb. nov. remain unknown.

Figures

FIGURE 7. Distribution of Megalotomus angulus (Hsiao, 1965) comb. nov..

FIGURES 1–6. Holotypes and their labels. Figs. 1–4, M. angulus (Hsiao, 1965) comb. nov.; Figs. 5–6, M. obtusus Ghauri, 1972 syn. nov.; Figs. 1 and 5, dorsal view; Fig. 2, lateral view; Fig. 3, ventral view; Figs. 4 and 6, labels. Scales in mm.

FIGURES 23–43. Male genitalia of Megalotomus spp. and Alydus calcaratus (Linnaeus, 1758). Figs. 23–25, M. angulus (Hsiao, 1965) comb. nov.; Figs. 26–28, M. junceus (Scopoli, 1763); Figs. 29–31, M. ornaticeps (Stål, 1858); Figs. 32–34, M. castaneus Reuter, 1888; Figs. 35–37, M. zaitzevi Kerzhner, 1972; Figs. 38–40, M. acutulus Liu & Liu, 1998; Figs. 41–43, Alydus calcaratus (Linnaeus, 1758); Figs. 23, 26, 29, 32, 35, 38, 41, genital capsules, dorsal view, parameres removed, pilosity only shown on left side; Figs. 24, 27, 30, 33, 36, 39, 42, left parameres, dorsal view; Figs. 25, 28, 31, 34, 37, 40, 43, same, lateral view. Scale in mm.