Bungona (Chopralla) bifida Shi & Tong, 2019

Shi, Weifang & Tong, Xiaoli, 2019, Genus Bungona Harker, 1957 (Ephemeroptera: Baetidae) from China, with descriptions of three new species and a key to Oriental species, Zootaxa 4586 (3), pp. 571-585 : 578-581

Bungona (Chopralla) bifida Shi & Tong , sp. nov.

( Figs 32–46 , 49 )

Material examined. Holotype. 1 mature nymph in ethanol, CHINA, Sichuan, Huagaoxi National Nature Reserve, Xuyong County, Shuiwei Town (24.20°N, 110.29°E, alt. 770m), 3.iv.2012, coll. Weifang Shi.

Paratypes (deposited in ethanol unless otherwise stated). 2 nymphs on slides and 4 nymphs, same date as holotype. CHINA, Guizhou: 1 nymph on mounted slides and 5 nymphs, Suiyang County, Kuankuoshui National Nature Reserve, Maoya Town , Zhongping (28.20°N, 107.04°E, alt. 640m), 26.iii.2012, coll. Weifang Shi. Hubei: 1 nymph, Yingshan County, Taohuachong Scenic (30.99°N, 116.04°E, alt. 600m), 24.vi.2014, coll. Weifang Shi. Sichuan: 1 nymph, Pingwu County, Laohegou (32.47°N, 104.67°E, alt. 1480m), 25.v.2012, coll. Weifang Shi.

Description. Mature nymph. Body length: 4.5–6mm, cerci 2.5–3mm, filament slightly shorter than cerci.

Colouration. Body with contrasting colour pattern ( Fig. 46 ) which fit well with the typical of the subgenus Chopralla .

Head. Antennae yellow-brown, approximately 1.8 x head width; pedicel slightly longer than scape ( Fig. 32 ). Labrum rectangular, width approximately 1.7 x length, anteromedial notch deeply with one small rounded lobe at base; each side of dorsal surface with one medial seta and one row of 3–4 submarginal setae sublaterally, which are all bifurcated at middle or 2/3 from base ( Fig. 37 ); ventrally bordered with feathered setae along margin and one disto-medial arc of very fine setae. Left mandible ( Fig. 34 ): incisors with 6 fused denticles, prostheca robust with 3 blunt and 3 acute denticles; spine-like setae between incisor base and molar present. Right mandible ( Fig. 35 ): incisors partially fused, inner and outer incisors with 6–7 denticles respectively, prostheca close to incisors and with slender medial process, neither bifid nor plumose but with small denticles apically; margin between incisors base and molar scattered with one tuft of spine-like setae. Hypopharynx: lingua with one median projection, covered with abundant setae. Maxillae ( Fig. 33 ): galealacinia with one row of 3–5 long basal setae and one short spine-like hump seta basally; maxillary palpus 2-segmented, slightly shorter than galealacinia and scattered with fine setae on surface, segment II approximately 2 x length of segment I. Labium ( Fig. 39 ): glossae slightly longer than paraglossae and subequal to paraglossae in width, ventrally with one row of 15–17 acute, long setae along inner margin and 3 stout setae and 1 robust setae at apex, dorsally with 5–6 acute, long setae along outer margin; paraglossae ventrally with one row of 17–19 acute, stout setae along outer margin and 5–7 long, stout setae along inner margin; labial palpus 3-segmented,segment I about 0.8 x length of segment II and III combined, scattered with numerous fine setae ventrally and pores dorsally; segment II wider than segment III, dorsally with one row of 4 long, simple setae apicomedially; segment III about 1.3 x maximum width.

Thorax. Pronotum surface smooth without tubercles. Hindwing pads minute but visible. Leg surfaces scattered with trapezoidal scale bases. Femora approximately 4 x maximum width, dorsally with one row of about 5–7 long, robust setae which approximately 1/2 femoral width and one pair of close-set stout subapical setae ( Fig. 38 ), ventrally with numerous pores; tibiae dorsally with fine setae, ventrally with one row of slightly acute stout setae and one pair of long, stout, slightly feathered setae apically; patella-tibial suture absent on fore tibia ( Fig. 40 ) and present on mid- and hind tibia submedially; tarsi dorsally with fine setae, ventrally with a row of short, acute setae. Claw with two rows of 3–4 denticles ( Fig. 41 ), apically with 4–5 furrows; two subapical setae present laterally but vestigial.

Abdomen ( Fig. 46 ): Abdominal tergal surface covered with trapezoidal scale bases and lanceolate scales densely ( Figs 42–44 ). Posterior margin of tergites II–VIII with semicircular, blunt spines which successively increasing in length backwards ( Figs 42–43 ); posterior marginal spines on tergites IX–X with wide gap medially ( Fig. 44 ); sternites generally yellowish-white, sternal surface with numerous pores and scale bases; sternites III–VI each with one pair of setal tufts anterolaterally ( Fig. 45 ); posterior margins of sternites V–IX with triangular spines; paraproct ( Fig. 49 ) subtriangular, with pores, trapezoidal scales bases and fine hairs on surface and 8–9 pointed spines along inner margin. Gills present on tergites I–VII, asymmetric lanceolate, moderately tracheated ( Fig. 46 ). Median caudal filament slightly shorter than cerci, inner margin and both sides of median caudal filament fringed with well-developed swimming bristles.

Imagoes. Unknown.

Etymology. The epithet bifida is from Latin adjective “bifidus”, meaning “cleft, divided into two parts” and referring to the shape of submarginal setae on labrum.

Distribution and biology. China (Sichuan, Hubei, Guizhou). The nymphs usually inhabit in slow-flowing mountain streams.

Comments. This new species, along with Bungona (C.) liebenauae ( Soldán, Braasch & Muu, 1987) , Bungona (C.) pontica Sroka, Godunko & Gattolliat, 2019 and Genus No. 2 sp. 1, sensu Müller-Liebenau, 1984, presents a very unique characteristic: right prostheca robust rather than bifid and plumose, which suggest that these four species may have an isolated position within the subgenus ( Soldán et al. 1987; Marle et al. 2016; Sroka et al. 2019). Bungona (C.) bifida sp. nov. is closely related to Bungona (C.) pontica from Turkey, but it can be easily distinguished from the latter by the following combination of features: (1) body colour pattern; (2) submarginal setae on labrum are forked apically ( Fig. 37 ) (vs. simple in pontica ); (3) segment I of labial palpus about 0.8 x length of segment II and III combined, segment III about 1.3 x maximum width (vs. segment I slightly longer than II and III combined, length of segment III subequal to the width in pontica ). The new species is similar to B. (C.) liebenauae in body colour pattern, while the pronotum of new species has no paired median tubercles. This new species is also similar to the ‘Genus No. 2 sp. 1’ described and illustrated by Müller-Liebenau (1984) from West Malaysia, however, body colour pattern, bifurcated submarginal setae on labrum, segment II of labial palpus dorsally with a row of 4 long, acute setae apicomedially and paraproct with 8–9 spines along the inner margin, clearly indicate that B. (C.) bifida sp. nov. is not conspecific with the Genus No. 2 sp. 1, sensu Müller-Liebenau, 1984.

Figures

FIGURES 32–40. Nymph of Bungona (Chopralla) bifida sp. nov. (32) antenna; (33) left maxilla; (34) left mandible; (35, 36) right mandible; (37) dorsal view of labrum; (38) foreleg; (39) labium (left: dorsal view; right: ventral view); (40) fore tibia.

FIGURES 41–46. Nymph of Bungona (Chopralla) bifida sp. nov. (41) mid-claw; (42) abdominal terga V and VI; (43) abdominal tergum VI; (44) abdominal terga IX and X; (45) abdominal sternum IV; (46) habitus of female nymph (dorsal view).

FIGURES 47–49. Paraprocts (47) Bungona (Centroptella) ovata sp. nov.; (48) Bungona (Centroptella) quadrata sp. nov.; (49) Bungona (Chopralla) bifida sp. nov.