Siphlonurus dongxi Li & Tong, 2023

Yang, Kun, Li, Xian-Fu, Tong, Xiao-Li & Cai, Qing-Hua, 2023, A new species of Siphlonurus Eaton, 1868 (Ephemeroptera, Siphlonuridae) from Yunnan, China, ZooKeys 1166, pp. 121-139 : 121

publication ID	https://dx.doi.org/10.3897/zookeys.1166.102847
publication LSID	lsid:zoobank.org:pub:6FF7402B-CCC7-4C28-B6D4-E919E2817F7C
persistent identifier	https://treatment.plazi.org/id/27AA2276-1CF5-4CA9-A6ED-5FCC5EC9F691
taxon LSID	lsid:zoobank.org:act:27AA2276-1CF5-4CA9-A6ED-5FCC5EC9F691
treatment provided by	ZooKeys by Pensoft
scientific name	Siphlonurus dongxi Li & Tong
status	sp. nov.

Treatment

Siphlonurus dongxi Li & Tong sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10 , 11 View Figure 11 , 12 View Figure 12 , 13 View Figure 13 , 14 View Figure 14 , 15 View Figure 15 , 16 View Figure 16 , 17 View Figure 17

Material examined.

Holotype: male imago, with final nymphal instar exuvia (in ethanol), China, Yunnan Province, Shangri-La City, Jiantang Town, Dugang river , 27°47′50.4″N, 99°48′43.3″E, 3361 m a.s.l., 12.VI.2022, coll. Xian-Fu Li GoogleMaps . Paratypes: 13 nymphs, 30 imagoes and 8 subimagoes reared from nymphs with same data as holotype. 5 nymphs from same location as holotype, but 1.VI.2021, coll. Yi-Hao Fang. GoogleMaps

Diagnoses.

The new species is similar to S. davidi . It can be distinguished from S. davidi by the colour of the imago, the morphological structure of egg, the forking point of MP, the transversal sclerite of the penis with two dorsal elongations, the dorsal elongation of the penis basally expanded, the elongations of the ventral sclerite, the posterolateral spines of tergum IX of imagoes and the first abdominal terga of the nymph, as well as the structure of the egg.

Descriptions.

Male imago (in ethanol). Body length 18.4-20.5 mm (excluding cerci), head width 3.3-3.5 mm, forewing length 17.3-18.6 mm, hindwing length 7.8-8.1 mm, antennae 1.4-1.6 mm. Ratio of hindwing: forewing length about 0.43.

Head: compound eyes contiguous (Fig. 1A View Figure 1 ), each of them spherical, upper portion and lower portion grey, without clear line between them (Fig. 1B View Figure 1 ).

Thorax: generally light yellow and dark brown, mesonotum anterior and legs basal with light yellowish stripes or rings (Figs 1A-C View Figure 1 , 2A-C View Figure 2 ). All legs light yellowish to dark brown, with distinct markings at both ends of femur and tibia (Fig. 2A-C View Figure 2 ). Length of femur: tibia: tarsus of foreleg = 1.3: 1.0: 2.4, tarsal segments from basal to apical = 2.2: 2.0: 1.8: 1.4: 1.0; femur: tibia: tarsus of midleg = 1.4: 1: 1.6, tarsal segments from basal to apical = 3.7: 2.5: 1.8: 1.0: 1.4; femur: tibia: tarsus of hindleg = 1.5: 1.0: 1.6, tarsal segments from basal to apical = 4.3: 2.8: 1.9: 1.0: 1.8. Inner margin of foreleg tarsus densely covered with circular bulges (Fig. 2A, G View Figure 2 ), and that of midleg and hindleg with stout setae (Fig. 2B, C, H View Figure 2 ). Outer margin of foreleg femur and tibia relatively densely covered with stout setae (Fig. 2A-F View Figure 2 ). Similar to other Siphlonurus species, all legs end with one blunt and one hooked claw. Forewings (Fig. 1D View Figure 1 ) generally hyaline except outer 1/3 of C and Sc, Sc and RA fields, base of forewing distinctly pigmented with black inlaid with yellow. Cross veins between C, Sc, RA, and RSa1 surrounded with distinct pigments, with dark spots. The forking point of MP is more proximal from that of fusion point of MA and RS. Anterior margin of forewing with small setae (Fig. 1F View Figure 1 ). Base of hindwing (Fig. 1E View Figure 1 ) distinctly pigmented with black inlaid with yellow, an additional large dark patch in the middle of Sc and RA cells, RA, and RS cells. Distal half of hindwing washed with black, making this area semitransparent, areas near centre and near margin of hindwing darker than others. Ratio of width: length about 0.79. Anterior margin without setae (Fig. 1G View Figure 1 ).

Abdomen (Fig. 1A-C View Figure 1 ) light yellow and dark brown, dorsal (Fig. 1A View Figure 1 ) and lateral sides (Fig. 1B View Figure 1 ) of terga II-X each with “W” shaped dark stripes; the ventral side (Fig. 1C View Figure 1 ) of terga II-VIII each with two dark symmetric spots and dark stripes, part and all of terga VIII-X distinct pigmented. Posterolateral spines of tergum IX well developed (Fig. 3D-F View Figure 3 ). Middle filament lost, terminal filament vestigial. Cerci lengths 29.5 mm, densely covered with long setae (Fig. 2I, J View Figure 2 ).

Genitalia. Penis relatively long (Fig. 3A-C View Figure 3 ), brown with dark brown markings, visible in distinct views (Fig. 3D-F View Figure 3 ); transversal sclerite with two elongations (Fig. 3A View Figure 3 , indicated by red arrow) and two semicircular white plates shown in dorsal and lateral views (Fig. 3A, B View Figure 3 ); dorsal elongation of penis arched without spines, basally expanded (Fig. 3A View Figure 3 , indicated by black arrow) apical half slim, penis lobe white fused without spines; elongations of ventral sclerite long, gradually widen from basal to subapical; styliger (Fig. 3D-F View Figure 3 ) 4-segmented, dark brown with stout setae, basal segment shortest but broadest, second segment about twice the length of third and apical ones together, the latter two subequal in length, each slightly longer than basal one. Styliger plate (Fig. 3F View Figure 3 ) slightly notched in middle.

Male subimago (in ethanol) (Fig. 4A-G View Figure 4 ) similar to male imago except for following characters: thorax and terga VIII-X overall lighter than the male imago (Fig. 4A-C View Figure 4 ); forewing (Fig. 4E View Figure 4 ) and hindwing (Fig. 4F View Figure 4 ) subhyaline; forewing without intercalaries at MP1 to iMP, with tiny setae on outer and hind margins; length of femur: tibia: tarsus of foreleg (Fig. 5A View Figure 5 ) = 1.4:1.0: 2.0, tarsal segments from basal to apical = 1.8: 1.6: 1.3: 1.0: 1.0; femur: tibia: tarsus of midleg (Fig. 5B View Figure 5 ) = 1.5: 1.0: 1.7, tarsal segments from basal to apical = 3.2: 2.1: 1.4: 1.0: 1.4; femur: tibia: tarsus of hindleg (Fig. 5C View Figure 5 ) = 1.5: 1.0: 1.5, tarsal segments from basal to apical = 3.9: 2.3: 1.6: 1.0: 1.8; inner of tarsus of foreleg with circular bulges and setae (Fig. 5D View Figure 5 ). The sclerite structure of penis incomplete (Fig. 6A-C View Figure 6 ). Styliger plate only shallowly curved, posterior margin waved; styliger with relative densely thick setae (Fig. 4G View Figure 4 ). Forewing length 17.0-17.5 mm, hindwing length 7.8-8.1 mm, cerci length 15.4-16.5 mm (Fig. 5E, F View Figure 5 ).

Female imago (in ethanol). Colour pattern similar to male; body length 19.6-22.2 mm, head width 3.1-3.4 mm, caudal filaments 20.7-24.4 mm, forewing 18.5-21.3 mm, hindwing 9.0-9.4 mm (Fig. 7A-F View Figure 7 ). Length of femur: tibia: tarsus of foreleg = 1.3: 1.0: 1.8, tarsal segments from basal to apical = 3.0: 2.3: 1.7: 1: 1.3; femur: tibia: tarsus of midleg = 1.5: 1.0: 1.6, tarsal segments from basal to apical = 3.2: 2.3: 1.6: 1: 1.4; femur: tibia: tarsus of hindleg = 1.5: 1.0: 1.6, tarsal segments from basal to apical = 3.8: 2.8: 1.7: 1.0: 1.6. Subgenital plate produced to 1/3 length of sternum VIII (Fig. 7B View Figure 7 ). Compared with male, forewing of female imago with sparse cross veins between C and Sc; all of Sc and RS fields, and outer part of RA and RS cells subhyaline (Fig. 7D View Figure 7 ). Inner margins of tarsus of foreleg, midleg and hindleg densely covered with spines (Fig. 8A-C, I View Figure 8 ).

Female subimago (in alcohol). Similar to male subimago except the tarsal segments of foreleg with more spines and usual sexual differences (Figs 8D-I View Figure 8 ). Length of femur: tibia: tarsus of foreleg = 1.4: 1.0: 1.6, tarsal segments from basal to apical = 3.1: 2.1: 1.5: 1: 1.6; femur: tibia: tarsus of midleg = 1.4: 1.0: 1.5, tarsal segments from basal to apical = 4.1: 2.6: 1.7: 1: 2.3; femur: tibia: tarsus of hindleg = 1.4: 1.0: 1.4, tarsal segments from basal to apical = 4.0: 2.5: 1.7: 1.0: 1.9. Inner margins of tarsus of foreleg, midleg and hindleg densely covered with spines (Fig. 8D-F, J View Figure 8 ). Forewing length 17.7-20.2 mm, hindwing length 8.9-9.1 mm, cerci length 13.2-14.2 mm.

Winged stages of Siphlonurus dongxi Li & Tong, sp. nov. (living) are shown in Fig. 9A-D View Figure 9 .

Eggs. Oval with irregular flat areas (Fig. 10A View Figure 10 ), length of 224-240 um, and width of 168-175 um. Chorion without obvious reticulation, with micropyle with or without reticulation (Fig. 10A-D View Figure 10 ). No accessory attachment structure apparent, but the egg surface has convex rough structures (Fig. 10A, B View Figure 10 ). The eggs were stuck tightly together, and the mass remained intact when placed in the water or ethanol.

Persistent mouthparts of winged stages.

The new species presents persistent mouthparts in winged stages; in ventral view of head, the labial and maxillary are present and clearly visible (Fig. 11A-D View Figure 11 , indicated by white arrow).

Final nymphal instar

(in ethanol) light yellow with red and dark markings (Fig. 12A, B View Figure 12 ), body length 14.1-16.7 mm (excluding cerci); head width 2.6-2.8 mm, cerci lengths 6.7-7.7 mm, median filament 5.6-6.8 mm, antennae 1.8-2.1 mm. Morphology and structure of the head (Fig. 12A, B View Figure 12 ) and mouthparts (Fig. 13A-H View Figure 13 ) of the new species similar to that of S. davidi . All legs similar (Fig. 14A View Figure 14 ), surface with short thick sparse setae, the apex of femora, tibiae, and tarsi with black spots or rings; femora broad, median marking black band; midleg with one clear patellar-tibial suture and hindleg with two ones on the tibiae (Fig. 14A View Figure 14 , indicated by red arrow). Length of femur: tibia: tarsus of foreleg = 1.8: 1.0: 1.3, femur: tibia: tarsus of midleg = 1.9: 1.0: 1.3, and femur: tibia: tarsus of hindleg = 1.8: 1.0: 1.2. Claws simple, without teeth (Fig. 14A View Figure 14 ). Abdomen with each tergite with one pair of parallel stripes near median line and tracheae with distinct pigmentation (Fig. 12A View Figure 12 ), posterolateral spines present on terga II-IX, surface with short, thick, sparse setae (Fig. 15A View Figure 15 ). Abdominal sternum (Fig. 14C View Figure 14 ) light yellow with dark spots and oblique dashes similar to that of winged stages; surface with short thick sparse setae (Fig. 14D View Figure 14 ); posterior margin of sternum IX of male and female concave (Fig. 15B, C View Figure 15 ). Middle instars light yellow without pigmentation (Fig. 14B View Figure 14 ). Caudal filaments with dark bands at the top of each segment, each segment with whorls of short, thick setae apically and long, hair-like setae laterally (Fig. 15D View Figure 15 ). Gills double on segments I and II; dorsal lamella of gill I (Fig. 16A View Figure 16 ) triangle, small, anterior rim relatively short, posterior margin straight. Dorsal lamella of gill II (Fig. 16C View Figure 16 ) leaf-shaped, anterior rim relatively short, posterior margin round, apically pointed. Ventral lamellae of gills I (Fig. 16B View Figure 16 ) and II (Fig. 16D View Figure 16 ) heart-shaped and their posterior margin slightly notched. Gills III (Fig. 5E View Figure 5 ), single, leaf-shaped, anterior rim relatively long, posterior margin round, apically slightly pointed. Gills IV-VII (Fig. 16F-J View Figure 16 ) single, oval, apically round, anterior rim relatively long; posterior margin round. Anterior rims of each gill with very short stout setae (Fig. 16J View Figure 16 ). Gill size gradually increased from gill I to gill III and decreasing from gill III to gill VII.

Etymology.

The specific epithet Siphlonurus dongxi , is named after the Chinese abbreviation of the Institute of Eastern-Himalaya Biodiversity Research, Dali University (https://www.eastern-himalaya.com.cn/contents/16/923.html). We hope that the Institute of Eastern-Himalaya Biodiversity Research can become an important platform for biodiversity research in the world. At the same time, we hope to cooperate with scientists from all countries through the International Centre of Biodiversity and Primate Conservation (http://www.icbpc.org/index.html).

Distribution.

China (Yunnan).

Ecology.

Nymphs of this new species prefer to live in pools or slow current areas with aquatic plants close to the bank in clear, high-altitude, wide streams (Fig. 17A View Figure 17 ). The last instar nymphs molted at noon and stayed on the grass for a relatively long time (Fig. 17B View Figure 17 ). In the laboratory, the larvae showed a behaviour of tearing water grass and collecting sediment (Fig. 17C View Figure 17 ). The emergence time is consistent with that observed in the field, the mature larvae crawled out of the water, the subimago stopped for a short time to drain a little water from the end of the abdomen before taking off (Fig. 17D View Figure 17 ). The subimago stage persisted until the third night while the observed lifespan of imagoes was about 4 days.