Research Article |
Corresponding author: Weifang Shi ( swf1102@163.com ) Academic editor: Eduardo Dominguez
© 2015 Weifang Shi, X.L Tong.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Shi W, Tong X (2015) First record of the genus Gratia Thomas (Ephemeroptera, Baetidae) from China with the description of a new species. ZooKeys 478: 129-137. https://doi.org/10.3897/zookeys.478.8995
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A new species of Baetidae, Gratia baibungensis sp. n., is described and illustrated based on nymphal stage collected from the southeastern Tibet (Xizang) and the genus is reported for the first time from China. This new species can be readily differentiated from its congeners by the absence of a protuberance on the posterior margin of the abdominal tergum X, glabrate simple submarginal setae on the labrum, and the posterior margin of sterna VI–IX having much longer spatulate setae.
Mayfly, Gratia , new species, Oriental Region, Eastern Himalayas, Tibet
The Eastern Himalayas is situated between the west of central Nepal and east of Myanmar, through southeastern Tibet in China to northeastern India. The area has been declared as a biodiversity hotspot (
In 2010, we conducted an exploration on the aquatic insect fauna in southeastern Tibet. The preliminary results revealed that mayflies have high species diversity, especially in Baetidae. Except for some species which are probably endemic to this region, most of mayfly fauna elements belong to the Indo-Malayan ecozone.
The genus Gratia was originally erected by
Nymphs were collected by kick-net from the riffles with cobble and gravel substrates in a 2nd-order shallow stream (approximately 1 m wide) at the Baibung Town, Medog County, southeastern Tibet. The specimens were directly placed into vials with 95% ethanol in the field and transferred into glass vials with 85% ethanol in the laboratory for preservation. Some were dissected under the stereomicroscope and were mounted on slides in Hoyer’s solution for examination and illustration. Mounted structures were examined and photographed under the microscope with a digital camera attached, and the images subsequently processed with Adobe Photoshop CS6. Type specimens are housed in the Collection of Aquatic Insects and Soil Animals, Department of Entomology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, China. The comparative specimens of G. sororculaenadinae and G. narumonae were provided by Dr Boonsoong of Kasetsart University, Thailand.
1 | Posteromedial dorsal protrusion presents on abdominal terga I to IX, submarginal setae on labrum simple and glabrate [China] | G. baibungensis sp. n. |
– | Posteromedial dorsal protrusion presents on abdominal terga I to X | 2 |
2 | All but the innermost two submarginal setae on labrum branched, second segment of labial palp with an inner-apical lobe [Thailand] | G. narumonae Boonsoong & Thomas |
– | All but the innermost two submarginal setae on labrum feathered, second segment of labial palp without an inner-apical lobe [Thailand] | G. sororculaenadinae Thomas |
Holotype. 1 mature nymph in ethanol, China, Tibet, Medog County, Baibung Town (29°14.65'N, 95°10.59'E, alt. 860m), 29.ix.2010, coll. Xianfu Li.
2 nymphs on slides and 2 nymphs in ethanol, same data as holotype.
Gratia sororculaenadinae Thomas: 3 mature nymphs, Thailand, Chiang Mai, Mae Hlang Stream, 16.i.2007; G. narumonae Boonsoong & Thomas: 3 mature nymphs, Thailand, Loei Province, Tarn Sawan waterfall, 12.ii.1999.
Mature nymph (Fig.
Head. Capsule yellowish-brown with transverse irregular markings on vertex and frons. Antennae approximately 1.5 times the width of head; dorsal surface of scape and pedicel scatter with fine setae, and with 3–4 and 2–3 scale-like setae respectively (Fig.
Thorax. Coloration pale brown with indistinct darker patterns. Surface of pronotum with four blunt tubercles. Metanotum with a finger-like protuberance medially (Fig.
Abdomen. Generally yellowish-brown. Mediodorsal posterior margin of terga I–IX each with a finger-like protuberance, successively decreasing in length backwardly (Figs
G. baibungensis sp. n. (a–e, g, h), G. narumonae (f) and G. sororculaenadinae (i). a habitus of lateral view b protrusion on abdominal terga VI–VII c paraproct d abdominal terga I–X e inner marginal bristles on cerci f inner marginal bristles on cerci g terminal filament h posterior margin of abdominal sterna VIII i sterna VII–VIII.
Unknown.
This new species is named after Baibung, the small town near the type locality.
China (southeastern Tibet).
Comparison with Thai specimens of two Gratia species (Table
all dorsal submarginal setae on labrum are glabrate and simple (vs. all but two innermost setae are branched and fimbriate in G. narumonae);
posterior margin on sterna VI–IX each with a row of continuous long spatulate setae approximately 2–4 times longer than wide (Fig.
gill margin with blunt setae, absent in G. narumonae.
Character | G. baibungensis sp. n. | G. narumonae | G. sororculaenadinae |
---|---|---|---|
Body length | 4–4.5 mm | 6.4 mm | 4.7–5.8 mm |
Number of scale-like setae on scape and pedicel | 5–7 | 7–9 | Approx. 30 |
Number of submarginal setae on labrum | 1+(7–8) | 1+(10–12) | 1+(15–16) |
Shape of submarginal setae on labrum | Simple and glabrate | Branched | Feathered |
Width/length ratio of labrum | 1.96 | 1.92 | 1.93 |
Inner-apical lobe on 2nd segment of labial palp | Present | Absent | |
Number of denticles on claw | 8–9 | 8–10 | 7–9 |
Finger-like protuberance on terga | I–IX | I–X | |
Ratio of scale-like setae length/width on posterior sterna VI–IX. | 2.0–4.0 | 1.0–2.0 | |
Number of scale-like setae on the inner margin of paraproct | 9–14 | 11–16 | 20–25 |
Bristles on inner margin of cerci | Each segment with 1–4 bristles (increasing in number towards terminal) |
Nymphs of G. baibungensis sp. n. inhabit the riffles area with cobble and gravel substrates in a 2nd-order shallow subtropical stream (approximately 1 m wide). However, both Thai species are found clinging to rock surfaces of tropical cascades: G. sororculaenadinae lives in limimadicolous zones and G. narumonae is more abundant in petrimadicolous zones.
The genus Gratia resembles Jubabaetis Müller-Liebenau in appearance by the presence a regular row of ciliate bristles on the dorsal margin of the femur, the protuberance on the posterior margin of abdominal terga, and the terminal filament reduced to one segment (
In comparison with the related genera, the genus Gratia is most closely related to the genus Baetiella in nymphal stages by sharing many similar morphological characters (Table
submarginal setae on labrum branched and fimbriate or simple and glabrate;
hind wing pads reduced or vestigial;
terminal segment of labial palpus conical with a tip on apex;
femora on dorsal margin with a regular row of ciliate (feathered) bristles, tibiae and tarsi with irregular row of fine glabrate setae;
femoral villopore present;
claws with a pair of subapical setae;
abdominal terga I–X (sometimes on I–IX) each with a finger-like protrusion on posterior margin, sterna and paraproct with conspicuous scale-like setae;
terminal filament reduced to one segment, inner margin of cerci with sparse bristles.
Character | Gratia | Baetiella |
---|---|---|
Antennae length | Approx. 1.5 times width of head | |
Scale-like setae on scape and pedicel | Present | Absent or present |
Submarginal setae on labrum | Branched and fimbriate or simple and glabrate | Simple and glabrate |
Shape of terminal segment of labial palpus | Conical with a tip on apex | Conical with or without a tip on apex |
Hind wing pads | Vestigial | Vestigial or well developed |
Metanotum with a protrusion medially | Present | Present or absent |
Bristles on dorsal margin of femur | In a regular row with ciliate (feathered) bristles | In a dense and irregular row with glabrate bristles |
Femoral villopore | Present | |
Ventral subapical bristle on tarsus | Absent | |
Claw with a pair of bowed subapical bristles | Present | |
Posteromedial dorsal protrusion on terga | Single, on I–X (or I–IX) | Single or double or absent, at most on I–IX |
Median caudal filament | One segment (conical) | One to multi-segment |
This work was supported by the National Natural Sciences Foundation of China (No. 30170121). Special thanks are due to Dr Boonsatien Boonsoong for providing the specimens of two Gratia species. The authors are grateful to Xianfu Li for collecting the specimens and to anonymous referees for their constructive comments.