Isonychia taishunensis Huang, Shen, Zhang & Cheng 2024, sp. nov.
Creators: name: Huang, Dong-Dong
name: Shen, Chen-Yang
name: Huang, Gui-Ying
name: Ye, Lin-Yu
name: Wu, Hui-Yuan
name: Zhang, Shu-Sheng
name: Cheng, Hong-Yi
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Isonychiidae
Isonychia
Isonychia taishunensis

description: Isonychia taishunensis Huang, Shen, Zhang & Cheng sp. nov.
(Figures 1–4)
Chinese name: ṺĤḘÑ
Material examined
Holotype: Female mature larva (in ethanol), Daxiyuan Provincial Nature Reserve (N 27°28′58′′, E 119°50′21′′), Taishun County, Zhejiang Province, China, 10. V. 2023, Chen-Yang Shen and Jie-Hong Ji. Paratypes (in ethanol): 7 larvae with the same data and collectors as holotype.
Description. Female, larvae (in ethanol): body length 14.7–15.7 mm, cerci fractured, 1.0–2.0 mm, terminal filament fractured, 5.9–6.0 mm; body dark brown, with a marked pale median longitudinal line from frons to tergite IV (Fig. 1 A–F); legs with pale and dark bands (Fig. 3 A–F), gills with purple or dark pigments (Fig. 4 A–G).
Head: genae dark, lateral 1/3 of clypeus brown but median 1/3 pale (Fig. 1 C); antennae length 3.9–4.0 mm, subequal to twice width of head. Anterior 1/2 of scape and pedicel darker than posterior 1/2. Flagellum of antennae smooth, with about 24 segments (Fig. 1 E). Frontal carina pale yellow, markedly sharp, area between three ocelli brown, area between median ocellus and compound eyes pale. Vertex smooth and convex. Base of ocelli dark (Fig. 1 D). Mouthparts: anterior margin of labrum with long hair-like setae, lateral 1/3 of dorsal surface covered with strong bristles while median 1/3 without; anterior margin pale, almost straight, lateral margins dark, slightly convex (Fig. 2 A). Left mandible: apex of both inner and outer incisor divided into three denticles, inner incisor slightly thinner than outer one; medial margin of molar lobe wide, slightly concave (Fig. 2 B). Right mandible: apex of outer incisor divided into three denticles, inner two, molar lobe relatively sharp compared with left one (Fig. 2 C). Hypopharynx: lingua whitish, nearly circular, with hair-like setae on apex; superlinguae whitish, possessing a yellowish line in middle, basal 1/3 of lateral margins of slightly convex, apex with longer hair-like setae (Fig. 2 D). Maxillary palpi yellowish, lateral margin brown, length ratio of segments I and II 1.0: 2.0; apical segment covered with strong hair-like setae and broader than basal one (Fig. 2 E). A whitish gill tuft on outer margin of cardo. Apex of lacinia with two conspicuous canines, mesal margin with a row of setae, one distinct spine among them (Fig. 2 E,F). Apex of galea processing a row of dense hair-like setae. Glossae-paraglossae of labium heart-shaped, brown, the latter significantly broader than the former, surface of them with dense hair-like setae. Labial palpi brown, length ratio of segment I and segment II 1.0: 2.0, outer margin of apical segment with long hair-like setae, inner margin of it with dense, brush-like setae, these near apex longer (Fig. 2 G). Thorax: dark brown, with a median pale line on dorsal surface, a thin dark line located within the pale line on cephalic 1/2 of mesothorax (Fig. 1 A). Meso and metasternum respectively with a projection directed posteriorly, the latter one shorter and slightly broader (Fig. 1 D). Coxa of forelegs attached with a gill tuft, base of the gill tuft pale, apex yellowish brown. Femora of foreleg with three yellowish bands distributed on base, middle and apex, both tibiae and tarsi with two yellowish bands on base and apex, but the bands on base of tarsi are relatively short, claw yellowish but its apex brown, four or five denticles can be spotted on the inner margin of foreclaw. Inner margin of foreleg with long hair-like setae but outer margin with spines, 5 on femora and tibiae respectively and 2 on tarsi; a distinct long spine on apex of tibiae, slightly bent, its length approximately equal to 2/3 tarsi. Length ratio of femora: tibiae: tarsi of foreleg 1.00: 1.06: 0.58 (Fig. 3 A,D). Pigments of midleg resemble to foreleg, both outer and inner margins with spine, apex of tibiae without a long bent spine. Claw of midleg with six or seven denticles. Length ratio of femora: tibiae: tarsi of midleg 1.00: 0.68: 0.37 (Fig. 3 B,E). Pigments pattern of hindleg resemble to midleg, the former possesses more spines on outer margin of femora, apex of tibiae without a long bent spine consistently. Ventral cleft of femora with four very short spines. Claw of hindleg with nine or ten denticles. Length ratio of femora: tibiae: tarsi of foreleg 1.00: 0.58: 0.36 (Fig. 3 C,F). Abdomen: brown, with a pale median line on terga I–IV (Fig. 1 A). Posterolateral angles of terga VIII and IX extended sharply, posterior margin of sternite IX caudally extended with its middle 1/2 strongly concave near semicircle (Fig. 4 H). Tergum X brown (Fig. 1 A). Gills I–VII similar in pigment and tracheation, but larger progressively from anterior to posterior. Gill plates VI and VII with small spines on apical margin, lobes I–V without. Each gill plate possesses three sclerotized ribs, two along anterior and posterior margins, respectively, and one on middle rear of dorsal surface. Two purple or dark speckles on each lobe, both attached to the mid rib. Each gill plate possesses a similar tracheation located between anterior rib and mid rib. Posterior margin of each gill plate more curvy than anterior one; a tuft of gill filament attached at the base of each lobe with darker apical 1/2 and pale basal 1/2 (Fig. 4 A–G). Caudal filaments: fractured, mesal margin of cerci and lateral margins of terminal filaments with strong hair-like setae (Fig. 1 F).
description: Published as part of Huang, Dong-Dong, Shen, Chen-Yang, Huang, Gui-Ying, Ye, Lin-Yu, Wu, Hui-Yuan, Zhang, Shu-Sheng & Cheng, Hong-Yi, 2024, A new species of Isonychia Eaton, 1871 (Ephemeroptera: Isonychiidae) from Taishun, China based on morphological characteristics and COX 1 gene, pp. 537-548 in Zootaxa 5437 (4) on pages 538-539, DOI: 10.11646/zootaxa.5437.4.6, http://zenodo.org/record/10985570