Microtendipes globosus sp. nov. (Diptera: Chironomidae) from Xishan Island, China is described and illustrated from a male imago. The new species is characterized by a spherical median volsella with 9–10 long setae, the basal lobe of the superior volsella with 10–12 setae, tergite IX without median seta, and the absence of pigment marks on the wings. An identification key to the males belonging to the genus Microtendipes in China is provided.
The genus Microtendipes Kieffer, 1915 includes 62 species distributed all over the world (Qi et al. 2012). Among them, 10 species have been reported from China (Wang 2000; Qi & Wang 2006; Qi & Wang 2010; Qi et al. 2012). The males of Microtendipes can be distinguished from all other Chironomini by one or two rows of stout, proximally directed setae on the fore femur. Additionally, the hypopygium of some species generally has a tubercle-like or wart-shaped median volsella often bearing a tuft of setae.
Six species of Microtendipes have been recorded from Zhejiang Province: M. britteni (Edwards, 1929), M. chloris (Meigen, 1818), M. pedellus (De Geer, 1776), M. truncatus Kawai & Sasa, 1985, M. yaanensis Qi & Wang, 2006, and M. zhejiangensisQi, Lin & Wang, 2012 (Qi & Wang 2010; Qi et al. 2012). Xishan Island, located in the southeast to Zhoushan City, Zhejiang Province, China has a subtropical climate. The island covers an area of 0.37 km2 and is surrounded by the East China Sea. In this paper, a new species of the genus is described from the island based on male imagines caught by sweep-net. A key to the males of Microtendipesin China is also provided.
Materials and Methods
All specimens were preserved in 75% ethanol until laboratory processing. For detailed examination, all specimens were dissected, cleared of musculature in 8% KOH, mounted on microscope slides following the procedure outlined by Sæther (1969), and then studied using a Nikon 80i microscope. The morphological nomenclature follows Sæther (1980).
Abbreviations of anatomical parts measured are as follows:
Total length - length of abdomen + length of thorax; Abdomen was measured from the concave anteriomedian margin of segment I to the apex of the gonostylus; the thorax was measured from the posterior margin of the postnotum to the anterior apex of the scutum in lateral view.
Wing length was measured from arculus to apex of wing.
Length of profemur.
Antennal ratio, length of 13th flagomere/length of flagellomeres 1–12.
5th/3rd: Length of 5th Palpomere/length of 3rd Palpomere.
Venarum ratio, length of Cubitus (Cu)/length of Media (M).
Length of (femur + tibia + ta1) /length of (ta2+ ta3 + ta4 + ta5)
Leg ratio, length of ta1/length of tibia.
Length of (femur + tibia)/length of ta1.
Hypopygium ration, length of gonocoxite /length of gonostylus.
Hypopygium value, total length/length of gonostylus times ten.
Fore leg; P2: Mid leg; P3: Hind leg.
femur; ti: tibia; ta1…tan: tarsus1…tarsusn.
Radius; R1: Radius 1 vein; R4+5: Radius 4+5 vein.
Male (n = 2)
TL 3.0–3.3 mm. WL 1.6–1.7 mm. Ratio TL/WL 1.80–1.95. Ratio WL/Pfe 1.86–1.89.
Coloration. Head yellow. Thorax greenish yellow with scutum, postnotum, median anepisternum II and preepisternum brown. Abdomen pale green, joints of tergites III–IX and hypopygium brown. Legs: femora, tibiae and fore ta1-2 with apical brown ring, remaining parts of fore, mid, and hind legs greenish yellow.
Head (Fig. 1). AR 1.23–1.29. Temporal setae 12–13 including 4–5 inner verticals, 4–5 outer verticals, and 3–4 postorbitals. Clypeus with 17–19 setae. Tentorium 138–140 µm long, 45–50 µm wide. Stipes 65–70 µm long, 30–32 µm wide. Palpomere lengths (in µm): 50–55, 30–32, 120–130, 215–220, 290–300. Ratio L: 5th/3rd 2.30–2.41.
Thorax (Fig. 2). Dorsocentrals 13–14, acrostichals lacking, prealars 3–4. Scutellum with 11–13 setae.
Wings (Fig. 3). Wing transparent, without markings. VR 1.20–1.23. Brachiolum with 2–3 setae and 6–9 sensilla campaniformia; R with 17–20, R1 with 14–16, R4+5 with 26–29 setae. Squama with 12–14 setae.
Legs (Fig. 4). Distal half of fore femur with 11–15 proximally directed setae in 2 rows, 200–230 µm long (Fig. 5). Spur on mid tibiae 35–45 µm long including 20–25 µm long comb, unspurred comb 20–23 µm long (Fig. 6); spur on hind tibia 33–40 µm long including 20–25 µm long comb, unspurred comb 20–25 µm long. Width at apex of fore tibia 44–50 µm, of mid tibia 40–50 µm, of hind tibia 42–50 µm. Lengths (in µm) and proportions of legs in Table 1.
Hypopygium (Fig. 7). Anal point 47–55 µm long, slender, tapering from base, and apically pointed. Tergite IX with 14–18 setae along posterior margin. Phallapodeme 38–45 µm long; transverse sternapodeme 35–50 µm long. Gonocoxite 135–150 µm long. Superior volsella 68–75 µm long, with 1 long lateral seta and basal lobe bearing 10–12 setae. Median volsella 13–15 µm long, spherical, with 9–10 long setae (Fig. 8). Inferior volsella digitiform, 85–100 µm long, with 19–24 setae. Gonostylus 103–110 µm long, with 9–11 setae along inner margin in distal ½. HR 1.31–1.36, HV 2.87–3.02.
Female, pupa and larva are unknown.
HOLOTYPE male, CHINA: Zhejiang Province, Zhoushan City, Xishan Island, N 29° 89.38′ E 122° 30.78′, 30-V-2013, coll. Y. F. Li. Paratype, 1 male, same as holotype. Specimens are deposited in the College of Life Science, Taizhou University, China.
Xishan Island, Zhejiang Province, China
The adult male of M. globosus sp. nov. can be distinguished from known species of the genus by the following combination of characters: a spherical median volsella with 9–10 long setae, the basal lobe of the superior volsella with 10–12 setae, tergite IX without median seta, and the absence of pigment marks on the wings.
Derived from the Latin “globosus”, meaning spherical, referring to the round shape of the median volsella.
The shape of the median volsella of M. globosus sp. nov. is characteristic within the genus. M. globosus sp. nov. is similar to M. numerosus Lehmann, 1979, M. schuecki Reiss, 1997, M. tuberosus Qi & Wang, 2006 and M. yaanensis Qi & Wang, 2006 in the presence of a basal lobe on the superior volsella. The main differences between these 5 species are given in Table 2.
Lengths ( m) and proportions of legs of Microtendipes globosus sp. nov.
Main differences between Microtendipes globosus sp. nov., M. numerosus, M. schuecki, M. tuberosus and M. yaanensis.
Key to the males of Microtendipes in China
1. Hypopygium with median volsella 2
—. Hypopygium without median volsella 7
2. Superior volsella with basal lobe 3
—. Superior volsella without basal lobe 5
3. Tergite IX without median seta M. globosus sp. nov.
—. Tergite IX with median setae 4
4. Fore femur with small tubercle; anal point parallel-sided, with 3 small lateral setae medially M. tuberosus Qi & Wang, 2006
—. Fore femur without small tubercle; anal point tapering from middle to truncated apex, with 2 small lateral setae medially M. yaanensis Qi & Wang, 2006
5. Superior volsella broad, rounded apically M. truncatus Kawai & Sasa, 1985
—. Superior volsella hook-like 6
6. Abdominal tergites I-V pale green, remainder black; fore tibiae pale medially, darkened at base and tip; anal point subtriangular M. pedellus (De Geer, 1776)
—. Abdominal tergites I-V dark green or blackish; fore tibiae blackish; anal point parallel sided M. chloris (Meigen, 1818)
7. Inferior volsella abruptly narrowed in apical half 8
—. Inferior volsella digitiform 9
8. Anal point apically slightly swollen and rounded; superior volsella with 4 dorsal setae and 2 basal setae M. angustus Qi & Wang, 2006
—. Anal point parallel-sided, slender, apex rounded; superior volsella with 7–10 dorsal setae and 4 long basal setae M. zhejiangensis Qi, Lin & Wang, 2012
9. Wing with dark markings M. quasicauducas Qi & Wang, 2006
—. Wing transparent, without markings 10
10. Superior volsella with 1 long basal seta and 3–7 dorsal setae; tergite IX with 13 setae along posterior margin M. britteni (Edwards, 1929)
—. Superior volsella with 3–4 dorsal setae; tergite IX with 4 setae along posterior margin M. confinis (Meigen, 1830)
Financial support from the National Natural Science Foundation of China (NSFC, grant No. 31301908, 31272284), the Zhejiang Provincial Natural Science Foundation of China (grant No. Y3100486), and Fauna of China (FY120100) is acknowledged with thanks. We also thank four anonymous reviewers for providing valuable comments on a previous version of the manuscript.