Cincticostella bifurcata, Xie, Hui, Jia, Yan-Yan, Chen, Ping, Jacobus, Luke M. & Zhou, Chang-Fa, 2009

Xie, Hui, Jia, Yan-Yan, Chen, Ping, Jacobus, Luke M. & Zhou, Chang-Fa, 2009, Two new Cincticostella species from China with a larval key to species of the genus (Ephemeroptera: Ephemerellidae), Zootaxa 2299, pp. 53-61 : 54-55

Cincticostella bifurcata sp. nov.

Mature larva: (in ethanol); body length 4.0–9.2 mm. Caudal filaments 3.0–5.5 mm. Body yellowish-brown. Ocelli, clypeus dorsal surface and vertex with various small tubercles and ridges ( Figs. 1 , 14 ). Mouthparts: anteromedian emargination of labrum shallow; dorsal labial surface with scattered setae and thick row of submarginal setae, free margins with relatively longer setae; ventral surface densely and irregularly covered with setae ( Fig. 2 ). Mandible with dense row of long setae on dorsal and lateral surface; outer incisor apex trifurcated, inner incisor bifurcated; prostheca represented by tuft of long setae; right mandible with tuft of bristles on inner margin ( Figs. 3, 4 ). Superlinguae of hypopharynx with row of setae on anterior margin, dorsal and ventral surfaces with thick setae; lingua with very sparse and tiny setae on dorsal and ventral surfaces ( Fig. 5 ). Maxilla with two larger spines which ventral margin with several denticulate, four setae on inner margin, bushy golden and long hairs on apex and lateral surface, galea-lacinia with several setae on inner margin near base; maxillary palpi 2-segmented, basal segment slightly broader, apex of 2nd segment with constriction ( Fig. 6 ). Labium with round glossae; glossae and paraglossae with setae on margins and dorsal surface; labial palpi 3-segmented, basal segment length subequal to 2nd segment, 2nd segment with setae on margins and dorsal surface, apical segment with no setae and much thinner than other segments; mentum small, submentum with sparse setae and spines on margins, irregular short spines and setae on dorsal surface, but smooth on ventral surface ( Fig. 7 ).

Thorax: Pronotum expanded laterally, with anterolateral angles projecting anteriorly, mesonotum projections broad, thoracic nota with various irregular ridges and tubercles, pair of longitudinal ridges and sharp posterior projections between forewing pads ( Figs. 1 , 14 ). Femora of all legs flattened, especially those of mid- and hindfemora. Femora of all legs longer than tibiae, and tibiae longer than tarsi. Forefemora with short spines and thick setae on margin, foretibiae and foretarsi with setae on both outer and inner margins( Fig. 8 ). Midleg and hindleg similar: femora flatted, with longitudinal ridge on dorsal surface, some setae on basal outer margin; outer margin serrate; outer and inner margins with sparse setae near apex of tibiae, whole tarsi with setae on margins ( Figs. 9, 10 ). Claws of all legs with 2 denticles, basal one bigger than distal one ( Fig. 11 ).

Abdomen: Pairs of tubercles present on abdominal terga 2-10, those on terga 2, 3, 4, 10 smaller than others; those on terga 5–8 strong, bifurcated apically ( Figs. 12 , 13 ); those on tergum 9 sharp-pointed but not bifurcated. Gills present on abdominal terga 3–7, gill 3 without medial transverse band of weakened membrane, dorsal lobe of gills 3–5 similar in shape, gill 6 diminished in size compared to gills 3–5, gill 7 very small and wholly covered by gill 6; ventral lamellae of all gills separated into several lobes, those of gills 3–5 further grouped into two parts, one clear cleft between them; those of gills 6–7 fused together, not bifurcate. Gill 7 located near posterolateral corner. Caudal filaments with tiny spines at articulations.

Etymology: bifurcata (feminine), from Latin adjective bifurcatus (bifurcate), indicates tubercles of abdominal terga 5–8 are bifurcated apically on body of larva.

Diagnosis: The new species is similar to C. femorata because of their significantly flattened bodies, legs and large projections on the pronotum and mesonotum. The new species can be distinguished from the latter by the following characters: (1) smaller body size; (2) body with many ridges and tubercles dorsally ( Fig. 1 ); (3) mid- and hind femora with smaller serrated free margins ( Figs. 9-10 ); (4) body and legs less flattened; (5) projections of thorax much smaller; (6) abdominal terga 5-8 with bifurcated tubercles( Fig. 13 ) instead of simple type as the C. femorata .

Material examined: holotype: 1 larva (L), Zi-Ma river (29.00978°N, 102.28003°E, elev. 2175m), Conservation station of Zi-Ma river, Conservation area of Li-Zi-Ping, Shi-Mian County, Si-Chuan Province, July 1, 2005, Chang-Fa ZHOU. Paratypes: 2L, same data as for holotype. 1 L, San-Gang (27.45°N, 117.40°E), Fu-Jian Province, June 7, 1987. 3 L, Mei-Zi river (26°20.905΄ N, 100°01.290΄ E, elev. 2319m, error 9m), Fu- Tian village, Niu-Jie countryside, Er-Yuan County, Da-Li State, Yun-Nan Province, July 8, 2008, Hui XIE, Yan-Yan JIA and Ping CHEN. All types deposited in the Mayfly Collection, College of Life Sciences, Nanjing Normal University, P. R. China

1, habitus of mature larva; 2, labrum (dorsum on left and venter on right); 3, left mandible; 4, right mandible; 5, hypopharynx (dorsum on left and venter on right); 6, right maxilla (ventral); 7, labium (dorsum on left and venter on right); 8, forleg; 9, midleg; 10, hindleg; 11, claw; 12, tubercle present on tergum 8.

Figures

FIGURE 13. Tubercles on abdominal terga 5 – 9 of C. bifurcata sp. nov. (lateral view) (digital photo)

FIGURES 1 – 12. Mature larva of Cincticostella bifurcata sp. nov.

FIGURES 14 – 15. Mature larvae of C. szechuanensis sp. nov.