Procloeon chinensis Chen & Zhou 2023, comb. nov.
Creators: name: Chen, Xiao-Fang
name: Zhou, Chang-Fa
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Baetidae
Procloeon
Procloeon chinensis

description: (2) Procloeon chinensis (She et al., 1995) comb. nov.
(Figs 1C, 2C–D, 3B, 3E, 4B, 4E, 5C–D, 6C–D, 6G, 6I, 7D–F, 9A–C)
Centroptilum chinensis She, Gui and You, 1995: 78, 79, fig. 8 (male). Types: male imago, China (Hainan).
Centroptilum chinensis: You & Gui, 1995: 38, fig. 34 (male).
Material examined: Holotype (male), Bawangling Nature Reserve, Qionghai City, Hainan Province, 10.V.1986, Shusheng She; 8 nymphs, 4 male imagoes (reared), 6 female imagoes (reared), Limushan Forest Park, Qiongzhong County, Hainan Province (108°44′22.41″E, 19°10′19.20″ N), 630 m, 15–18.IV.2023, Dewen Gong, Xiaofang Chen and Xinhe Qiang.
Description. Male: See She et al. 1995.
Female (in alcohol, first description): Body length 7.0– 7.5 mm, forewings 5.5–6.0 mm, hindwings 0.8–1.0 mm; body pale to pale yellowish (Fig. 2D). Compound eyes grey, pronotum pale, meso- and metanota grey, posterior margins of metanota brown to dark brown (Fig. 2D). Forewings transparent, distinct 7–9 cross veinlets in stigmatic area; marginal intercalaries longer than the distance between them to neighboring veins. Hindwings with hook-like costal projection and two longitudinal veins. Terga of abdomen grey to yellowish, with red posterior margins, terga I–VI with clear dark tracheae (Fig. 2D); sterna III–IX with red posterior margins.
Nymph (in alcohol, first description): Body length 5.5–6.0 mm, antennae 1.8–2.0 mm, caudal filaments 1.8–2.0 mm; body generally pale brown, with deep brown to chocolate dots, markings and stripes, making its body mottled (Fig. 5C). Vertex with a pair of yellow brown stripes or lines, extending to clypeus discontinuously, more distinct around ocelli and base of clypeus; ocelli pale but with dark base. Antennae pale, scape slightly wider than pedicel, two of them subequal in length; length of antennae ca. 2.5x head width. Mouthparts: Labrum nearly semicircular, posterolateral angles sclerotized and pigmented; anterolateral angles round and unclear; front margin with a deep V-shaped notch; anterior half of dorsal surface with hair-like setae, anterior margin with a row of relatively long setae; an additional row of sub-marginal spatulate setae besides median notch; ventral surface with two tufts of submedian hair-like setae. Two mandibles nearly symmetrical except molars, lateral margins smooth, slightly waved; outer incisor of them with four apical tips, inner one with three, ventral margin of inner incisor serrated; two incisors almost fused but suture between them clear; prostheca with expanded and serrated apex; a tuft of spine-like setae between molar and prostheca. Maxillae with clear suture between galea and lacinia, its mesal margin with sparse hair-like setae, apex with spine-like setae, canine with three spines. Maxillary palpi with tiny and sparce hair-like setae on surface, segment ratios I:II:III = 1.7:1.8:1.0, two margins of segment I nearly parallel, segment II progressively widened slightly, segment III slightly narrowed from base to apex, length: width of it = 4.0: 1.0 (Fig. 4E). Labium with sparse hair-like setae on both surfaces, margins of glossae, paraglossae with spine-like setae; glossae and paraglossae long triangular; labial palpi also with sparse tiny hair-like setae, segment III with spine-like setae on apical margin; segment II distinctly narrower than others; apex of segment I narrower than base but those apices of segment II and III wider than base; segment III nearly trapezoidal, both lateral margin convex, inner one clearer than outer one; apical margin nearly straight (Fig. 4B). Lingua and superlinguae of hypopharynx with indistinct hair-like setae on apex. Thorax: Pronotum gray to pale brown, median portion slightly paler than anterior and lateral margins; width: length 2.8: 1.0; gray mesonotum and metanotum with irregular pale portions and dots (Fig. 5C); hindwing pads tiny but visible; three pairs of legs similar in structure and color pattern: legs generally pale, joints slightly greyer; femur with a longitudinal median red line and a subapical reddish brown dot; with sparse hair-like and spine-like setae on outer margin, inner margin with spine-like setae only; tibia and tarsus with spine-like setae on inner margins (Fig. 6C); length ratio of forefemur: tibia: tarsus 1.5:1.0:1.0, length ratio of mid- and hindfemur: tibia: tarsus 1.8:1.0:1.0. Claw ca. 0.5x tarsus, with two rows of denticles, distal half denticles broader and larger than proximal half (Figs 6D, 7D–E).
Abdomen: Tergum I pale to pale grey, terga II–VII with three brownish to chocolate markings respectively, each nearly triangular; two submedian ones near anterior margin, one at middle; those markings of terga II, III and VI larger than others, making whole terga look brown; tergum VIII with three brown markings near posterior margin, anterior half of tergum IX brown, posterior margin of tergum X dark (Fig. 5C). Sterna pale but each with a pair of brown stripes (Fig. 5D). All posterior margins of terga and sterna dark. Terga II–X and sterna V–IX with a transverse row of denticles on posterior margins (Figs 5C–D). Posterolateral angles of terga II–X extended into sharp spines; lateral margins of terga VIII–IX with a row of spines. Inner margin of paraproct with a row of 6–7 spines (Fig. 6G). Gills on terga I–VII, gills I and VII slightly smaller than others; gills I–VI with double lamellae, ventral one peltate, dorsal one elongate (Figs 9A–B); gill VII single (Fig. 9C); lamellae of gills I–VII with sclerotized lines on costal margin; main tracheae and its branches of all gills dark and clear. Caudal filaments with a reddish dark ring and a row of spines on every fourth segment (Fig. 6I), basal half pale, apical half brown; cerci with dense hair-like setae on mesal margins, spine-like setae on outer margins; terminal filament with hair-like setae on both margins; those setae progressively longer from base to apex.
Egg: Oval, surface with regular net-like ridges (Fig. 7F).
Diagnosis. Males of this species can be identified by its orange compound eyes (Fig. 2C), orange to red transverse lines on terga and sterna, hook costal projection of hindwings (Fig. 1C), unspecialized segment I of forceps and tiny segment III (Figs 3B, E). Its hindwings are slightly wider than in P. pennulatum, and its segment I of forceps is slightly narrower.
Females of this species can be recognized by their red abdominal lines and dark tracheae (Fig. 2D).
Nymphs can be differentiated from P. pennulatum by darker abdomen (with transverse lines on posterior margins of terga or sterna) (Figs 5C–D), caudal filaments pigmented in distal half (Fig. 5C) (P. pennulatum has a median band) (Fig. 5A).
Remarks. This species was originally described in the genus Centroptilum based on male imago. The female imago and nymph are described here for the first time. Key characters, such as like male genitalia and nymphal mandibles, show it is a Procloeon species.
The male, female and nymph of this species in this study are associated by COI sequences. The distance of them is only 0.002 –0.005 (Table 1).
Distribution. China (Hainan Province).
description: Published as part of Chen, Xiao-Fang & Zhou, Chang-Fa, 2023, A contribution to knowledge of Procloeon Bengtsson, 1915 from the Chinese mainland (Ephemeroptera: Baetidae) with description of a new species, pp. 163-175 in Zootaxa 5353 (2) on pages 166-170, DOI: 10.11646/zootaxa.5353.2.6, http://zenodo.org/record/8427226