Macropelopia (Macropelopia) pergrandis Tang et Niitsuma, 2020

Tang, Hongqu & Niitsuma, Hiromi, 2020, Revision of the Chinese Macropelopia (Diptera: Chironomidae: Tanypodinae) with description of a new species, Zootaxa 4834 (2), pp. 207-218 : 208-212

Macropelopia (Macropelopia) pergrandis Tang et Niitsuma sp. nov.

( Figure 1 )

Type material. Holotype: M ( EJNU), CHINA: Yunnan Prov., Anning City, Shuishenqiao Scenic Area , alt. 1850 m, 26.v.2018 . Paratypes: 1P, CHINA: Yunnan Prov., Dehong Pref., Lianghe City, Qimu Town , alt. 1300 m, 27.x.2016; 2 Pe , Yunnan Prov., Honghe Pref., Pingbian County, Daweishan NNR, alt. 2100 m, 5.vi.2017; 4P, 2 Pe , Yunnan Prov., Nujiang Pref., Fugong City, Pihe Town , Fugong Lake , alt. 4000 m, 15.x.2017; 2P, 3 Pe , Yunnan Prov., Dali City, pond in campus of Dali University , alt. 2150 m, 20.v.2018; 2M (teneral), 3P, 4 Pe , Yunnan Prov., Dali City, Yangbi County, Shimeiguan Scenic Area , alt. 1730 m, 21.v.2018; 2 Pe , Yunnan Prov., Baoshan City, Longyang Dist., Mangkuan Ethnic Town , Gaoligongshan NNR, Baihualing Station , alt. 1550 m, 22.v.2018; 2 Pe , Yunnan Prov., Diqing Pref., Xianggelila City, Zange Town , stream, alt. 3066 m, 19.vi.2018, X. Wen; 1P , Tibet Autonomous Region, Nyingchi Pref., Medog County, Yarlung Tsangpo Grand Canyon , Zhamog-Medog Road , between mileposts 62K and 80K, alt. 2345 m, 5.viii.2015; 3 Pe , Sichuan Prov., Ya’an City, Bifengxia Scenic Area , alt. 1010 m, 21.vii.2018, W. Han & T. G. Gou .

Etymology. From the Latin pergrandis , very large, referring to the very large plastron plate in the pupal thoracic horn.

Description. Male (n = 3). Total length 4.8–7.0, 5.7 mm.

Coloration. Head dark brown. Thorax mostly brown with dark anepisternum, preepisternum and postnotum; scutal vittae indistinct. Abdomen entirely pale brown. Wing ( Figure1A ) with darkened cross-veins, and light infuscate markings on membrane. Legs mostly brown, and somewhat darker on apices of tibiae.

Head. Temporals 36–40, 38, multiserial. AR 1.6–1.8, 1.7. Clypeus with 18–20, 19 setae. Lengths (µm) of palpomeres1–5: 70–87, 77; 100–126, 109; 175–200, 190; 210–276, 249; 335–411, 382. Pm 4 /Pm 3 1.2–1.4, 1.3; Pm 5 /Pm 4 1.5–1.6, 1.5.

Thorax. Aps 18–24, 21, laterally; Ac 78–84 (2), biserial; Dc 42–45, 43, multiserial; H 16–35, 27; Su 2; Pa 48–55, 51, multiserial; As II 7–8, 7; Pes 10–16, 12; Scts 51–68, 60; Pns 11–14, 12, biserial. ScuT 15 (2) µm high.

Wing. Length 3.8–4.3 (2) mm. Squama with 61–64 (2) setae. VR 0.90–0.93 (2).

Legs. Ti I spur 100–123, 111 µm long with 19–20, 20 side teeth. Ti I comb consisting of 11–15, 13 small bristles. Ti II spurs 90–101, 97 and 60–74, 66 µm long with 16–18, 17 and 13–14, 14 side teeth, respectively; inner spur 1.4–1.5, 1.5 times as long as outer spur. Ti III spurs 90–101, 94 and 60–74, 66 µm long with 16–18, 17 and 12–14, 13 side teeth, respectively; inner spur 1.4–1.5, 1.4 times as long as outer spur. Ti III comb consisting of 11–12, 11 bristles. Lengths and proportions of leg segments as in Table 1.

Hypopygium ( Figure 1B ). T IX with 20–22, 21 posterior setae. Gonocoxite somewhat cylindrical, 300–329, 316 µm long, 2.3–2.7, 2.5 times as long as broad at middle, basally with setiferous swelling. Gonostylus 135–145, 140 µm long, gently curved inwards, with narrowed apical half. HR 2.2–2.3, 2.3.

Pupa (n = 10). Body length 8.5–10.1, 9.1 (9) mm.

Coloration. Exuviae light brown. Abdomen ( Figure 1C ) with distinct pigmentation pattern; T II–VII brown except with large pale areas around basal tubercles of D 1 -setae; scar and apophyses dark brown.

Cephalothorax. Thoracic horn ( Figure 1D ) flattened, 850–1075, 923 (9) µm long, 2.1–2.4, 2.3 (8) times as long as its broadest width; plastron plate 1.2–1.7, 1.4 (8) times as long as broad, bean-shaped, with strongly concave basal margin; PpL/ThL 0.53–0.72, 0.64 (9); internal supporting rods extending through respiratory atrium, fused with plastron plate at several points.

Abdomen. T I with elongated dark scar. Shagreen extensive on all tergites, mainly consisting of serial rows of 2–4 spinules, but posteriorly replaced by larger spines. Intersegments II/III–VIII/IX with shagreen consisting of blunted spinules. D 1 -seta ( Figure 1E ) stout, spiniform, arising from large tubercle on T II–VI, and from small tubercle on T VII; positioned 0.70–0.85, 0.77 (9) from anterior segment margin on T IV, 0.71–0.81, 0.75 (9) on T V, 0.60–0.77, 0.69 (9) on T VI, 0.57–0.67, 0.60 (9) on T VII. D 2, 3 -setae short and simple; D 3 -seta at most 1.5 times as long as D 1 -seta on T III–V. A VII ( Figure 1F ) with 6 LS-setae, VIII with 5 LS-setae; LS 1 -seta located 0.22–0.30, 0.26 (9) from anterior segment margin on A VII, 0.26–0.37, 0.32 (9) on A VIII. Anal lobe 1125–1300, 1217 (8) µm long, 2.3–2.6, 2.5 (8) times as long as broad with lateral fringe of about 100 setae; anterior and posterior macrosetae located 0.04–0.08, 0.07 (9) and 0.10–0.14, 0.11 (9), respectively, from anterior lobe margin; male genital sac 0.33–0.37, 0.35 (4) times as long as lobe.

Female and larva. Unknown.

Remarks. The adult male and pupa were associated using pharate males collected from Dali City, Yunnan Prov., May 21, 2018 by the first author. These males have a relatively low antennal ratio (less than 2.0), a foretibial comb with many tiny bristles (more than 10), a pale brown abdomen, and a hypopygium with setiferous tergite IX and gonostyli gently curved inwards and narrowed in the apical half.

The species belongs to the nebulosa group defined by the pupa with 6 LS-setae on segment VII. So far, the following five described species of this group has been known from the Holarctic region: M. (M.) nebulosa (Meigen) , M. (M.) decedens (Walker), M. (M.) fehlmanni (Kieffer), M. (M.) paranebulosa Fittkau and M. (M.) rossaroi Lencioni et Marziali. The males, as well as the larvae, of these species are very similar to each other. Therefore, the pupal morphology is important to separate species and the ratio PpL/ThL has been regarded as a discriminator by the recent authors ( Lencioni & Marziali 2005, Michalova et al. 2014). For the comparison, major pupal characters of these species are summarized in Table 2.

The pupa is similar to that of M. (M.) paranebulosa in having a thoracic horn with a plastron plate strongly concaved along the basal margin, large basal tubercles of D 1 -seta on the abdominal tergite IV, and short and simple D 3 -setae. In the former, however, the plastron plate is bean-shaped, longer than wide and the PpL/ThL is 0.53–0.72, whereas in the latter, the plastron plate is kidney-shaped, wider than long, and the PpL/ThL is lower although it differs among authors perhaps because of the geographical variation: 0.21–0.29 and 0.14–0.22 in the Russian population according to Makarchenko & Petrova (1988) and Michailova et al. (2014), respectively, and 0.30–0.49 in the Japanese population according to Niitsuma et al. (2004). Further, the pupa has an elongated dark scar on the tergite I, which is unique within the species group.

The male of M. (M.) decedens has wings bearing a dark marking only on the cross-vein r-m ( Roback 1971), and those of M. (M.) fehlmanni and M. (M.) rossaroi possess gonostyli strongly tapered in distal half (see Fittkau 1962, fig. 23 for the former; Lencioni & Marziali 2005, fig. 1 for the latter). The male of the present new species most resembles those of M. (M.) nebulosa and M. (M.) paranebulosa in the wing markings and the gonostylus somewhat parallel-sided and broadened in basal half to two thirds with an attenuated tip, but may be separable by the lower antennal ratio of 1.6–1.8. The males of M. (M.) nebulosa and M. (M.) paranebulosa tend to possess a higher antennal ratio, 2 or more: 2.0– 2.3 in M. (M.) nebulosa according to Fittkau (1962) and 2.2–2.6 in M. (M.) paranebulosa according to Niitsuma et al. (2004).

Kownacki et al. (1976) reported the pupa of an unnamed species, presumed subspecies of M. nebulosa , from Afghanistan, and Hazra & Chaudhuri (2000) redescribed Macropelopia nebulosa from India based on the all life stages. However, these species differ from European M. (M.) nebulosa (Meigen) mainly in the pupal morphology: in the former two species, the thoracic horn has a plastron plate concaved along the basal margin, the basal tubercle of D 1 -seta is relatively large on the tergite IV, and the D 3 -seta is short and simple ( Kownacki et al. 1976, figs 23, 24; Hazra & Chaudhuri 2000, fig 4A, D), whereas in the latter, the basal margin of plastron plate is more or less straight, the basal tubercle of D 1 -seta is smaller, and the D 3 -seta is long and hooked distally ( Fittkau 1962, figs. 39, 52). These Afghan and Indian species are also similar to the present new species in the plastron plate of thoracic horn, which is bean-shaped, longer than wide. Additionally, in these pupae, the basal tubercle of D 1 -seta is large on the tergite IV, and the D 3 -seta is simple, neither hooked apically and nor exceptionally longer than the D 1 -seta. However, the current pupa of the new species is distinct from both the pupae in the strongly concaved basal margin of the plastron plate, the high PpL/ThL of 0.53–0.72, and the pigmented scar on the tergite I. According to Kownacki et al. (1976) and Hazra & Chaudhuri (2000), both the pupae have plastron plates slightly concaved along the basal margin, the tergite I has no scar, and the PpL/ThL is 0.44 in the Afghan pupa ( Michailova et al. 2014) and 0.33–0.40 in the Indian pupa ( Hazra & Chaudhuri 2000). The Afghan and Indian species may be conspecific because of the similarities of the pupal morphology although the male and larva of the former are unknown.

The present new species has been collected from mountainous areas (1000–4000 m a.s.l.) in Oriental China (Yunnan, Sichuan and Hubei Provinces, and Tibet Autonomous Region). Although several larvae belonging to this genus could be also captured with many pupae of the present species in slowly flowing small streams and ponds, we could not associate the larvae with the pupae of the present species .

Figures

FIGURE 1. Macropelopia (Macropelopia) pergrandis Tang et Niitsuma sp. nov., male (A, B) and pupa (C–F).A, Wing; B, hypopygium, dorsal view; C, abdominal segments I–III, dorsal view; D, thoracic horn; E, abdominal segment IV with chaetotaxy, dorsal view; F, abdominal segments VII–IX, dorsal view. Abbreviations: L, thoracic horn length; l, plastron plate length.