Regulaneuria chongchongae, Mu & Huang, 2023

Mu, Pengxu & Huang, Xiaolei, 2023, Revision of the genus Regulaneuria (Ephemeroptera, Heptageniidae, Ecdyonurinae), with description of a new species, Zootaxa 5353 (3), pp. 235-249 : 237-243

publication ID	https://doi.org/ 10.11646/zootaxa.5353.3.2
publication LSID	lsid:zoobank.org:pub:DAA8680A-A064-407F-94D0-F20D5F57B2CE
DOI	https://doi.org/10.5281/zenodo.8427432
persistent identifier	https://treatment.plazi.org/id/14558B19-FFE4-FFE0-0EC9-2577FD797B99
treatment provided by	Plazi
scientific name	Regulaneuria chongchongae
status	sp. nov.

Treatment

Regulaneuria chongchongae sp. nov.

Figs 1 – 6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 , 8A – C, 8G – I View FIGURE 8

Type-material. Holotype: male imago, CHINA, Hainan, Baoting Li and Miao Autonomous County, Qixianling Hot Spring National Forest Park [ HNBT01 Aa] (18°.701242 N, 109°.698858E, alt. 333 m), 19.I.2023, leg. Pengxu Mu, ( FAFU) GoogleMaps . Paratypes: CHINA, Hainan: 7 male and 2 female imagos , 1 male and 3 female subimagos, 10 nymphs, same data as holotype (in ethanol), ( FAFU); 3 nymphs (in ethanol); Qiongzhong Li and Miao Autonomous County, Limushan Forest Park [ HNQZ05 Aa] (19°.213664 N, 109°.758414 E, alt. 550 m), 14.I.2023, leg. Pengxu Mu, ( FAFU); GoogleMaps 1 nymph (in ethanol), Wuzhishan City , Wuzhishan Rainforest Scenic spot [ HNWZ01 Aa] (18°.867700 N, 109°.682853E, alt. 637 m), 15.I.2023, leg. Pengxu Mu, ( FAFU) GoogleMaps .

Description. Male imago (in ethanol). Body length 7.0 (8.5) mm; forewing length 7.1 (8.5) mm; cerci length 21.6 (28.1) mm.

Head ( Fig. 2A View FIGURE 2 ). Compound eyes grayish blue, widely separated by a distance ca. 2.5 times frontal ocellus width; ocelli apically pale gray, dark brown basally; antennae with scapes whitish-yellow, pedicels and flagella brown. Area between compound eyes yellowish except those margins along inner sides of ocelli and antennae reddish-brown.

Thorax. Pronotum yellowish-white with dark brown coloration in median and posterolateral part. Mesonotum with medioscutum dark brown and submedioscutum pale brown. Mesosternum with two dark brown U-shape stripes on anterior margins of basisternum and furcasternum respectively. Legs ( Fig. 2C View FIGURE 2 ): All legs with similar color pattern: femur yellowish-brown with a brown band at middle and a dark brown band at apex; tibia yellowish with base and apex brown; tarsal segments yellowish except apex brown. Foreleg: length ratio of femur (2.3 mm):tibia:tarsus 1.0:1.0:2.0, length ratio of tarsal segments from basal to apical 1.0:1.3:1.2:1.1:0.3. Midleg: length ratio of femur (1.9 mm): tibia:tarsus 1.0:0.7:0.9, tarsal segments arranged in decreasing order as 1, 2, 3, 5, 4. Hindleg: length ratio of femur (2.0 mm):tibia:tarsus 1.0:0.8:0.7, tarsal segments arranged in decreasing order as 1, 2, 3, 4, 5. All claws of legs similar, one blunt and one hooked. Wings ( Fig. 2D View FIGURE 2 ): Forewing hyaline except pterostigmatic area milky and opaque, and with two dark brown maculations between Sc and R1 at apex and subapex; crossveins generally reduced in number (ca. 86 in total) especially at basal half, costal and subcostal fields with ca. 17 crossveins; most crossveins except those in and around radial field at distal half trimmed with brown pigments; all crossveins except those in costal and subcostal fields and wing base arranged into 5-6 rows. Hindwing hyaline but with pale brown pigmentation along outer margin at distal half; costal projection slightly blunt, near base.

Abdomen. Abdominal terga I – VIII nearly transparent but with posterior margins dark brown, terga III – VIII with pair dark brown sublateral spots and posterolateral oblique stripes, and terga IV – VIII with single pale brown longitudinal stripe medially. Sternum I with dark brown U-shape stripe on anterior margin; sterna II – IV with pair dark brown oblique stripes on lateral margins ( Figs 3A, B View FIGURE 3 ). Genitalia ( Figs 3E, F View FIGURE 3 ): Styliger convex medially and with two blunt projections sublaterally; gonostyli with segment IV ca. 3/4 times segment III length, together slightly shorter than half segment II. Penes fused, penis lobes round apically and hollowed out; median titillators well developed. Cerci yellowish-white, with joints of segments dark brown.

Female imago. Body length 8.8 (9.2) mm; forewing length 10.6 (11.3) mm; cerci length 20.5 (23.5) mm. Similar to male imago except as follows: Compound eyes separated by a distance ca. 6.0 times frontal ocellus width; area between compound eyes yellowish-white at anterior half and dark brown at posterior half ( Fig. 1B View FIGURE 1 ). Foreleg: length ratio of femur (3.0 mm):tibia:tarsus 1.0:0.7:0.7, tarsal segments arranged in decreasing order as 3, 1, 1, 4, 5; midleg: length ratio of femur (3.0 mm):tibia:tarsus 1.0:0.8:0.5, tarsal segments arranged in decreasing order as 1, 2, 3, 5, 4; hindleg: length ratio of femur (3.5 mm):tibia:tarsus 1.0:0.8:0.3, tarsal segments arranged in decreasing order as 1, 1, 3, 5, 4. Abdominal terga II – VIII with broad brown longitudinal stripes medially, sublateral spots larger than those of male imago ( Fig. 3C View FIGURE 3 ). Sternum I with U-shape stripe on anterior margin; sterna II – VII light brown medially, and sterna II – VI with pair dark brown oblique stripes on lateral margins ( Fig. 3D View FIGURE 3 ). Subgenital plate greatly elongated posteriorly reaching the posterior margin of sternum VIII; subanal plate tongue-shape, elongated and narrowed ( Fig. 3G View FIGURE 3 ).

Male subimago. Similar to male imago except the following: Foreleg: length ratio of femur (2.2 mm):tibia: tarsus 1.0:0.8:1.0, tarsal segments arranged in decreasing order as 1, 2, 2, 5, 4; midleg: length ratio of femur (2.2 mm):tibia:tarsus 1.0:0.7:0.6, tarsal segments arranged in decreasing order as 1, 2, 2, 5, 4; hindleg: length ratio of femur (2.4 mm):tibia:tarsus 1.0:0.8:0.5, tarsal segments arranged in decreasing order as 1, 2, 3, 5, 3. All tarsomeres of all legs covered with blunt U-shape microlepides. Wings gray and semi-hyaline; pigmented crossveins on forewing similar to male imago but paler in color; hindwing without brown pigmentation at distal half.

Female subimago. Similar to female imago except the following: Foreleg: length ratio of femur (2.8 mm): tibia:tarsus 1.0:0.9:0.6, tarsal segments arranged in decreasing order as 1, 2, 2, 5, 4; midleg: length ratio of femur (2.9 mm):tibia:tarsus 1.0:0.8:0.4, tarsal segments arranged in decreasing order as 1, 2, 4, 5, 2; hindleg: length ratio of femur (3.2 mm):tibia:tarsus 1.0:0.8:0.3, tarsal segments arranged in decreasing order as 1, 3, 4, 5, 2. Subgenital plate not extended posteriorly as female imago; subanal plate broad basally with narrowed distal half and truncated apex. Wings and microlepides on tarsomeres similar to male subimago.

Nymph. Body length 7.2 (8.6) mm; cerci length 9.4 (10.2) mm. Coloration pattern as in Figs 4A – C View FIGURE 4 .

Head. Head capsule ( Fig. 5A View FIGURE 5 ) slightly expanded laterally, posterolateral and poster margins slightly concave; subanterior margin with three large pale spots, one at middle and a pair near the base of antennae. Labrum ( Figs 5B – D View FIGURE 5 ): slightly expanded laterally with round apex; anterodorsal margin with dense and long setae; on ventral surface, each side of anterior margin with a median single row of ca. 10 stout setae and 2 – 3 row of stout setae laterally. Mandibles ( Fig. 5E View FIGURE 5 ): with numerous long setae along outer margins; left mandible with prostheca composed of 12 – 14 feathered bristles, kinetodontium subequal in length to incisor; right mandible with prostheca composed of 10 – 12 feathered setae, kinetodontium shorter and slender than incisor. Hypopharynx ( Fig. 5F View FIGURE 5 ): superlingua curved with relatively acute apex, row of hair-like setae on outer margins from base to sub-apex; lingua bell-like with tuft of short setae at apex. Maxillae ( Figs 5G, H View FIGURE 5 ): galea-lacinia covered with slightly feathered setae on ventral surface; crown of the galea-lacinia with ca. 17 comb-shape setae, median ones bearing 17 – 20 teeth; proximal dentiseta bifurcated in the middle, and proximal branch fringed; two distal dentisetae with distal one single and fringed and proximal one similar to proximal dentisetae. Labium ( Figs 5I, J View FIGURE 5 ): glossae nearly oval with narrow apex; paraglossae moderately expended laterally, nearly two times longer than wide.

Thorax. Pronotum extended laterally, obviously wider than head ( Figs 4A, C View FIGURE 4 ). Supracoxal spurs weakly developed ( Fig. 6B View FIGURE 6 ). Legs ( Figs 6A View FIGURE 6 , 8A – C View FIGURE 8 ): all legs with similar coloration pattern as in Fig. 6A View FIGURE 6 ; forefemur with long hair-like setae on outer margin and small bristles on upper face and inner margin, and those bristles on upper face with pair longitudinal median ridges and truncated apices; foretibia ca. 0.9 times forefemora length, outer margin with long hair-like setae at basal half, inner margin with row of sparse, short bristles; foretarsus ca. 0.3 times foretibia length, outer margin with short hair-like setae; midleg similar to foreleg, except tibia ca. 0.8 times femur length and with long hair-like setae on whole outer margin; hindleg similar to midleg, except tibia and tarsus with pinnate bristles on inner margins. Claws of all legs with 4 – 5 subapical denticles.

Abdomen. Abdominal terga I – VII yellowish-brown, with two submedian diffused pale spots and two sublateral dark brown stripes; terga VIII – X yellowish with two sublateral dark brown stripes only ( Fig. 6C View FIGURE 6 ). Sterna yellowish, sterna II – VI with two sublateral brown dots. Posterolateral projection moderately developed on segments III – VIII ( Fig. 6D View FIGURE 6 ). Tergalii ( Fig. 6E View FIGURE 6 ): Lamella of tergalius I with convex posterior margin and blunt apex; lamellae of tergalii II – VI similar, with anterior margin greatly expanded and apices round; tergalius VII expended anteriorly at basal half and suddenly narrowed at distal half, and with fine setae along both margins. Caudalii yellowish, with whorled spines on articulations ( Fig. 6F View FIGURE 6 ).

Egg. KCTs and small rounded tubercles randomly scattered all over the surface of the chorion; micropyle located equatorially and with single smooth margin ( Figs 8H, I View FIGURE 8 ).

Etymology. The name of new species is dedicated to Miss Han Chongchong, we thank her for the location information of the new species.

Biology. Regulaneuria chongchongae sp. nov. was found in several areas from Hainan Island. The nymphs were collected in upper streams with a high degree of shade, which width varies from 1.0 – 6.0 m and depth varies from 0.1 – 1.0 m at the time of collection ( Fig. 9B View FIGURE 9 ). The velocity of flow of these streams showed great variations at different sections, and those sections with lower flow rates and more substrates tended to have higher density of nymphs. These nymphs seem to swim away quickly when turning up stones and rarely stay on stones. Other mayflies collected from these streams included Alainites sp. , Baetis (Rhodobaetis) sp., Centroptella (Chopralla) colorata Soldán et al. , Choroterpes (Euthraulus) sp., Epeorus sp. , Labiobaetis sp. , Procloeon sp. , Prosopistoma ocellatum Shi & Tong.