Notacanthella jinwu Li & Jacobus, 2022

Li, Xian-Fu, Sun, Ye-Kang, Liu, Zi-Ye, Jacobus, Luke M. & Xiao, Wen, 2022, A new species of Notacanthella Jacobus & McCafferty, 2008 (Ephemeroptera, Ephemerellidae) from Yunnan, China, ZooKeys 1103, pp. 25-44 : 25

Notacanthella jinwu Li & Jacobus sp. nov.

Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10

Material examined.

Holotype: male, with final nymphal instar exuvia (in ethanol, deposited in MBDU), China, Yunnan Province, Dali City, Mt. Cangshan, Mocan Stream , 25°39'22.2"N, 100°11'10.1"E, 2020 m a.s.l., 23.X.2021, coll. Xian-Fu Li . Paratypes: 10 nymphs, 6 imagos and 3 subimagos reared from nymphs with same data as holotype; 10 nymphs and 4 imagos reared from nymphs from same location as holotype, but 23.X.2021, coll. Xian-Fu Li; 20 nymphs and 5 imagos reared from nymphs from type locality, but 19.IX.2021, coll. Xian-Fu Li; 1 nymph, Dali City , Mount Cangshan , Qingbi Stream , 25°39'05.5"N, 100°9'08.4"E, 2316 m a.s.l., 14.V.2021, coll. Kun Yang; 3 nymphs, Qingbi Stream, 25°40'11.0"N, 100°11'02.7"E, 1974 m a.s.l., 3 nymphs, Qingbi Stream, 25°39'20.2"N, 100°9'44.1"E, 2098 m a.s.l., 16.VIII.2021, coll. Kun Yang; 3 nymphs, Qingbi Stream, 25°39'08.6"N, 100°9'27.3"E, 2221 m a.s.l., 21.VIII.2021, coll. Kun Yang; 2 nymphs, Yunnan, Bincuan City, Mount Jizushan , Shazhi River , 25°56'54.4"N, 100°21'40.0"E, 1947 m a.s.l., 21.VIII.2021, coll. Rong-Long Yang and Kun Yang. All the specimens are deposited in MBDU .

Diagnoses.

The new species is similar to N. commodema because both have nymphs with two pairs of flattened tubercles on the head, genae that are not produced into sharp projections, seven prominent tubercles on the pronotum, seven tubercles on the mesonotum, claws of all legs with five or six basal denticles, and posterolateral projections of abdominal segment IX that are not elongate. The new species can be distinguished from N. commodema by the shape and orientation of its longer and sharper abdominal tergal tubercles and by the structure of abdominal sternum IX in males, which is subquadrate with rounded posterolateral projections (see identification key, below). The ecological distribution of our new species is in subtropical high-altitude areas, in contrast to N. commodema , which is found in areas below 1000 m elevation. The imagos of other Notacanthella species are not known, so a diagnosis is not possible. Likewise, a meaningful diagnosis of the egg stage is not possible, either. See discussion for further information and remarks.

Descriptions.

Final nymphal instar (in ethanol). Body length 12.08-12.30 mm (excluding tails); head width 2.15-2.54 mm, cerci lengths 9.04-10.50 mm, median filament 9.57-10.60 mm. Body coloration brown with dark brown markings (Fig. 1A, B ).

Head. Brown, with two pairs of tubercles; large occipital tubercles and small suboccipital tubercles (Fig. 2A ). Maxillae with maxillary canine length greater than relative width (Fig. 2B ), and with lateral serration (Fig. 2C ); three-segmented maxillary palp covered with hair-like setae, segment length ratio from base to apex = 3.1: 2.4: 1 (Fig. 2D ). Left mandible (Fig. 2E ) and right mandible (Fig. 2F ), with three outer incisors and two inner incisors, with tuft of short setae present in concavity close to molar area, and densely covered with irregularly ordered hair-like setae on dorsolateral surface. Labrum densely covered with setae, anterior margin somewhat concave medially (Fig. 2G ). Hypopharynx: sublingua rounded with anterolateral hair-like setae, lingua oval with anterolateral, short setae (Fig. 2H ). Labium densely covered with hair-like setae and with transverse stripes; glossae length greater than width; labial palp three-segmented, first and second segments subequal in length, third segment smaller (Fig. 2I ).

Thorax. Pronotum without anterolateral projections; lateral margins convex; dorsal surface with seven tubercles: one medially, two submedially, two laterally, and two sublaterally; lateral tubercles prominent, but sublateral tubercles inconspicuous (Fig. 3A, B ). Mesonotum with paired small and rounded anterolateral projection; lateral margins convex; dorsal surface with seven tubercles: two anteromedially, two medially, and three posteromedially (Fig. 3A, B ). Foreleg: femur brown with dark brown bands medially and distally; dorsal margin with chalazae, short fine setae, and a few stout, pinnate, and clavate setae; ventral and outer margins densely covered with short, fine setae and few stout pinnate and clavate setae; dorsal and ventral aspects of tibia and tarsi brown with short, fine setae, few short, stout, pinnate, and clavate setae; apex of tibia and inner margin of tarsi with set of acute setae; ratio of femur: tibia: tarsus = 2.0: 1.9: 1 (Fig. 3C ). Middle leg similar to foreleg, but ratio of femur: tibia: tarsus = 2.3: 2.5: 1 (Fig. 3C ). Hind leg similar to foreleg and middle leg, but ratio of femur: tibia: tarsus = 2.5: 3.0: 1 and outer margin of tibia with row of long, stout, pinnate, and clavate setae (Fig. 3F ). Long hair-like setae densely distributed at base of outer margin of each femur. Various stout setae of different lengths, some pointed and some rounded, present at apex of each tarsus (Fig. 3G-I ). All claws with one row of five or six denticles (Fig. 3G-I ).

Abdomen. Abdominal terga brown, convex; terga III-VIII with prominent wing-like lateral projections (Fig. 4A ); paired dorsal tubercles on segments I-X, tubercles short and tips parallel at base of segments I-IV, longer and tips progressively divergent on segments V-IX, long and divergent tubercles on segment IX, shorter and tips parallel on segment X; lateral projections of segment IX not extending beyond segment X (Fig. 4A, C ). Lateral projections and apices of tubercles of each segment with stout, clavate setae (Fig. 4D, E ). Posterior margin of sternum IX of male straight (Fig. 5A ); posterior margin of sternum IX of female concave (Fig. 5B ). Gills III-V with bifurcate and multifoliate ventral lamellae, gill VI ventral lamella integral and multifoliate, gill VII ventral lamella multifoliate; dorsal lamella of gill III rounded (Fig. 4F ), dorsal lamellae of gills IV-VII paddle-shaped (Fig. 4G-J ). Caudal filaments brown with whorls of small, almost rounded, scale-like setae and few long, unbranchedsetae at apex of each segment (Fig. 5C ).

Character variability.

We examined specimens of different instars and some characters may vary between earlier and later instars, similar to its close relative, N. commodema ( Allen 1971; Auychinda et al. 2020b).

Male imago (in ethanol). Body length 11.73-13.17 mm (excluding tails), head width 2.13-2.36 mm, cerci lengths 11.31-13.98 mm, median filament length 11.07-14.52 mm, forewing length 14.12-17.31 mm, hindwing length 3.92-6.88 mm. Compound eyes contiguous, upper portion reddish brown and lower portion black. Body generally reddish brown to dark brown (Fig. 6 ). Prosternum dark brown, with slightly concave central longitudinal carina. Mesonotal scutellum with three projections at posterior margin, middle projection short (Fig. 7B ). Forewings generally hyaline, veins reddish brown; cells of costal and subcostal fields tinted with reddish brown; cross veins in stigmatic area slightly oblique, and those between costal and subcostal separated into two rows cells; MA forked 1/4 distance from base to margin; MP forked 2/3 distance from base to margin (Fig. 7C ). Hindwings hyaline, veins reddish brown; leading margin slightly concave; MA single, MP margin forked symmetrically (Fig. 7D ). Fore legs reddish brown to dark brown, middle and hind legs reddish brown (Fig. 7E ). All legs without distinct markings. Femur: tibia: tarsus of foreleg = 1: 1.3: 1.2, tarsal segments from basal to apical = 1: 3.5: 3.1: 2.0: 1.4; femur: tibia: tarsus of midleg = 1.8: 2.1: 1.0, tarsal segments from basal to apical = 1: 1.9: 1.8: 1.4: 2.3; femur: tibia: tarsus of hindleg = 2.8: 3.6: 1, tarsal segments from basal to apical = 1: 1.9: 1.8: 1.4: 2.3. Claws of all legs similar, one blunt and one hooked. Abdomen reddish brown to dark brown, terga I-VII each with one or three longitudinal median pale stripes; terga VIII-IX each with large and irregular pale stripes, posterolateral projections of terga VIII-IX each extended into sharp spine-like structures.

Genitalia. Forceps covered with stout setae (Fig. 8D, E ); segment 3 globular; segment 2 angled inward distally and with slight subapical constriction (Fig. 8A, B ). Penes lobes compact, with linear groove on ventral face; lobes separated by slight cleft; anteromedial, dorsomedial and lateral stout setae absent; dorsolateral projection absent (Fig. 8A-C ).

Female imago. Colour pattern similar to male; body general reddish brown to dark brown (Fig. 9A ). Body length 8.08-14.1 mm (excluding tails), head width 1.65-2.2 mm, cerci lengths 10.08-10.32 mm, median filament length 9.66-11.3 mm. Prosternum reddish brown, with slightly convex central longitudinal carina. Mesonotum dark brown; scutellum with three projections at posterior margin, middle projection short. Forewing 13.28-16.5 mm, hyaline, with veins reddish brown; cells C and SC tinted with reddish brown. Hindwing 3.45-4.8 mm, totally hyaline, with veins reddish brown. Each leg reddish brown to dark brown; length of femur: tibia: tarsus of foreleg = 2.0: 1.8: 1, tarsal segments from basal to apical = 1.4: 1.7: 1.7: 1: 2.4; femur: tibia: tarsus of midleg = 2.6: 2.7: 1.0, tarsal segments from basal to apical = 1: 1.1: 1.2: 1: 2.1; femur: tibia: tarsus of hindleg = 3.1: 3.7: 1.0, tarsal segments from basal to apical = 1.1: 1: 1.2: 1.2: 2.2. Abdomen reddish brown to dark brown; subgenital plate produced to 1/5 length of sternum VIII; posterior margin of subanal plate without obvious median cleft (Fig. 9B ).

Male subimago. Body reddish brown (Fig. 10A ); wings brown and subhyaline; scutellum with three long, pointed posterior prolongations (Fig. 10B ); tarsus of foreleg shorter than femur, caudal filaments shorter than body length.

Female subimago. Body red brown; wings brown and subhyaline; scutellum with three long, pointed posterior prolongations; tarsus of foreleg shorter than femur, caudal filaments shorter than body length. Posterior margin of subanal plate without obvious median cleft, similar to female imago. Otherwise, similar to male subimago except for usual sexual differences.

Egg (dissected from female imago). Length 171-218 μm, width 134-158 μm. Ovoid with one small polar cap (Fig. 11A, B ); chorion with reticulations, strands ridged; mesh with multiple central tubercles (Fig. 11A, C, D ); several lateral attachment structures in subpolar areas (Fig. 11A, C ); knob of attachment structure and micropyle (Fig. 11D ) distributed near equator (Fig. 11A, C ), micropyle round and micropylar rim absent.

Etymology.

The name, Notacanthella jinwu (feminine), comes from Jin Wu, a Chinese mythical creature. In China, ancient people took "Jin Wu" as the alias of the sun. The reddish brown subimago is similar to the color of a rising sun. Given that the emergence of N. jinwu sp. nov. happened at sunrise, we can imagine N. jinwu as the body double of the sun. The common name of this species is the Jinwu spiny crawler mayfly.

Distribution.

China (Yunnan).

Ecology.

The stream in Dali City and Binchuan County where the nymphs of N. jinwu were collected is 1.2-5.0 m wide, with a natural water body depth 5-35 cm. It contains stones of various sizes, aquatic plants, and litter (Fig. 12A ). During collecting, the nymphs were found hiding under stones or climbing on aquatic plants, moving slowly and swimming weakly. The nymphs are only distributed between 1947 and 2316 m above sea level (Fig. 12C ). In indoor conditions, nymphs generally hid under rocks (Fig. 12B ), but they were more active when eating aquatic plants and litter. The last instar nymphs molted at sunrise and flew after a short rest. The subimago stage persisted for 2 days and molted during the daytime. The observed timespan of the imago stage was about 3 days. According to our monthly field survey, the nymphs of N. jinwu Li & Jacobus, sp. nov. are found from May to November.

Figures

Figure 1. Notacanthella jinwu Li & Jacobus, sp. nov. A middle instar, dorsal habitus B last nymphal instar, dorsal habitus.

Figure 2. Notacanthella jinwu Li & Jacobus, sp. nov. A head, anterior view B maxilla C maxillary canines with lateral serration D maxillary palp E left mandible F right mandible G labrum H hypopharynx I labium.

Figure 3. Notacanthella jinwu Li & Jacobus sp. nov. A thorax of last nymphal instar, dorsal view B thorax of early instar, dorsal view C legs, dorsal view, from top to bottom foreleg, midleg and hindleg D setae on femur E setae on femur F setae on tibia of hind leg G claw of foreleg H claw of midleg I claw of hindleg. (M = median tubercle; SMs = submedian tubercles; Ls = lateral tubercles; SLs = sublateral tubercles; SMAs = submedian anterior tubercles; SMMs = submedian tubercles at middle; MP = median posterior tubercle; SMPs = submedian posterior tubercles).

Figure 4. Notacanthella jinwu Li & Jacobus sp. nov. A abdomen, nymph, dorsal view B abdominal segments I-III of last Final nymphal instar C abdominal segments VII-X of last Final nymphal instar D tubercle of abdominal tergum VII of last Final nymphal instar E lateral margins of abdominal segment VII of last Final nymphal instar F gill III G gill IV H gill V I gill VI J gill VII.

Figure 5. Notacanthella jinwu Li & Jacobus sp. nov. A structure of sternum IX of male nymph B structure of sternum IX of female nymph C Final nymphal caudal filaments.

Figure 6. Male imago of Notacanthella jinwu Li & Jacobus sp. nov. (living).

Figure 7. Male imago of Notacanthella jinwu Li & Jacobus sp. nov. A lateral view of body B dorsal view of thorax (lateral scutellar projection indicated by red arrow) C forewing D hindwing E legs, from top to bottom foreleg, midleg and hindleg.

Figure 8. Male imago genitalia of Notacanthella jinwu Li & Jacobus sp. nov. A ventral view B dorsal view C lateral view D forceps segments 2 and 3 E bottom of forceps segment 2.

Figure 9. Female imago of Notacanthella jinwu Li & Jacobus sp. nov. A lateral view B terminal parts of abdomen, ventral view.

Figure 10. Male subimago of Notacanthella jinwu Li & Jacobus sp. nov. A living specimen B thorax, dorsal view.

Figure 11. Egg of Notacanthella jinwu Li & Jacobus, sp. nov. A lateral view B polar cap C bottom view of the opposite pole D knob of attachment structure (K) and micropyle (M).

Figure 12. Habitat and distribution map of Notacanthella jinwu Li & Jacobus, sp. nov. A, B habitats in Dali City (note recently molted nymph in B) C distribution map of N. jinwu sp. nov. in Dali Bai Autonomous Prefecture.