Procloeon strumiferum, Chen & Zhou, 2023

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, Zootaxa 5353 (2), pp. 163-175 : 171-173

publication ID	https://doi.org/ 10.11646/zootaxa.5353.2.6
publication LSID	lsid:zoobank.org:pub:FC763CA9-E0E3-4C6F-AC9E-0E33980816A5
DOI	https://doi.org/10.5281/zenodo.8436571
persistent identifier	https://treatment.plazi.org/id/03A0D44F-FFB4-9A51-DE8C-FE2CFB5036C3
treatment provided by	Plazi
scientific name	Procloeon strumiferum
status	sp. nov.

Treatment

(3) Procloeon strumiferum sp. n.

( Figs 1A, 1D View FIGURE 1 , 2E–F View FIGURE 2 , 3C, 3F View FIGURE 3 , 4C, 4F View FIGURE 4 , 5E–F View FIGURE 5 , 6E–F, 6H, 6J View FIGURE 6 , 7G–I View FIGURE 7 , 8A–F View FIGURE 8 , 9D–H View FIGURE 9 , 10A–B View FIGURE 10 )

Material examined: Holotype: China: male imago (reared), 1.5 km upstream creek to Huanglongjia Reservoir, Hongwei Forest Farm, Jiangning District, Nanjing City, Jiangsu Province (118°96′82″E, 31°97′17″N), 11.VI.2022, Changfa Zhou, Dewen Gong , Xinhe Qiang , Mengyao Li and Muhe Deng ; Paratypes: 5 nymphs, 2 female imagoes (reared), 3male imagoes (reared), same as the holotype; 5 nymphs, same place as the types, 27.IX.2022, Changfa Zhou; 3 female imagoes (reared), 2 male imagoes (reared), 1.0 km upstream of Explorsion Park, Zijin Mountain, Nanjing City, Jiangsu Province (118°84′88″E, 32°02′35″N), 22.IX.2022, Chang-Fa Zhou.

Mature nymph (in alcohol): Body length 4.0–5.0 mm; antennae 2.4–2.6 mm; terminal filament 1.7–1.9 mm, cerci 1.8–2.0 mm. Body pale with various brown to chocolate dots and markings ( Fig. 5E View FIGURE 5 ). Antennae pale, scape subequal to pedicel in length. A pair of brown stripes on vertex to clypeus. Mouthparts similar to P. chinensis except: (1) anterior margins of labium slightly convex ( Fig. 8F View FIGURE 8 ); (2) maxillary palpi two-segmented, segment I: II 0.6: 1.0 ( Figs 4F View FIGURE 4 , 8C View FIGURE 8 ); (3) inner margin of segment III of labial palpi slightly less convex ( Fig. 4C View FIGURE 4 ). Mandibles and hypopharynx are similar to the former species P. chinensis ( Figs 8B, D–E View FIGURE 8 ).

Thorax: Width: length of pronotum 3.0: 1.0, with irregular brown markings ( Fig. 5E View FIGURE 5 ). Hindwing pads visible. Legs pale, femur with subapical band ( Fig. 6E View FIGURE 6 ). Length ratio of forefemur: tibia: tarsus 1.4: 0.8: 1.0, ratio of mid- and hindlegs 1.8: 1.0: 1.0. Claw ca. 0.5x tarsus ( Fig. 6F View FIGURE 6 ); each claw with two row of denticles on basal half, progressively larger from base to apex ( Figs 7G–H View FIGURE 7 ).

Abdomen: Terga III, VI and IX darker than others, each of them with a pair of pale submedian stripes; other terga pale, with irregular brown to dark markings ( Fig. 5E View FIGURE 5 ). Terga I–X and sterna V–IX with spines on posterior margins; terga III–X with sharp posterolateral spines; terga VIII and IX with lateral spines; terga and sterna with reddish line on posterior margins, usually divided into two parts ( Figs 5E–F View FIGURE 5 ). Sterna with lateral brown patches ( Fig. 5F View FIGURE 5 ). Gills on terga I–VII; gills I–V with double lamellae but gills VI–VII single ( Figs 9E–H View FIGURE 9 ); ventral lamellae of gills I–VII nearly peltate, but dorsal lamellae of gills I–V nearly elongate and gradually shortened ( Figs 9E–F View FIGURE 9 ); margin of gill VII with very sparse tiny hair-like setae ( Fig. 9D View FIGURE 9 ); tracheae of gills dark and contrasting. Paraproct with 8–9 marginal spines ( Fig. 6H View FIGURE 6 ). Caudal filaments pale yellowish, with reddish ring and a ring of denticles on every fourth segments ( Fig. 6J View FIGURE 6 ), a contrasting brown band present subapically; spine pattern similar to P. chinensis .

Male imago: Body length 5.0–6.0 mm, forewings 4.0–5.0 mm, hindwings 0.2–0.3 mm, cerci 10.0–12.0 mm. Head: antennae pale ( Fig. 10A View FIGURE 10 ), the upper portion of compound eyes pale to pale orange, their apices broader than base; lower portion gray. Thorax: pale to yellowish ( Fig. 2E View FIGURE 2 ). All legs uniformly pale. Length ratio of femur: tibia: tarsus of foreleg 0.8: 1.0: 1.0, tarsal segments 1–5 arrangement from long to short as 2, 3, 4, 5, 1. Apex of tibia slightly broadened. Length ratio of femur: tibia: tarsus of midleg 1.3: 1.2: 1.0, tarsal segments 1–3 arranged in decreasing order as 3, 1, 2. Length ratio of femur: tibia: tarsus of hindleg 1.2: 1.2: 1.0, tarsal segments 1–3 arranged in decreasing order as 3,1, 2. All legs with one acute and one blunt claw. Forewings transparent while base of C, Sc and R1 pigmented with brown, subcostal brace light brown; 7–10 crossveins at pterostigma region; length of marginal intercalaries subequal to distance between them and neighboring longitudinal veins ( Fig. 1A View FIGURE 1 ). Hindwings small, costal margin slightly convex, lack costal projection and veins ( Fig. 1D View FIGURE 1 ). Abdomen: terga I–VI translucent, terga VII–X pale to yellowish; posterior margins of each tergum with two transverse lines, tergum IV and sometimes VII with additional a pair of oblique reddish stripes ( Fig. 2E View FIGURE 2 ). Segment I of forceps slightly widened apically, segment II with a depression near base, its apex slightly expanded; segment III enlarged apically ( Figs 3C, F View FIGURE 3 ), length 2.7x width. Cerci pale ( Fig.10A View FIGURE 10 ).

Female imago: Body length 5.0–6.0 mm, forewings 4.0–5.0 mm, hindwings 0.3–0.5 mm, cerci 10.0–12.0 mm. Coloration similar to male ( Fig. 10B View FIGURE 10 ). Length ratio of femur: tibia: tarsus of foreleg 1.0: 0.9: 1.0, tarsal segments 1–5 arrangement from long to short as 2, 3, 4, 5, 1. Apex of tibia slightly broadened. Length ratio of femur: tibia: tarsus of midleg 1.3: 1.2: 1.0, tarsal segments 1–3 arranged in decreasing order as 3, 1, 2. Length ratio of femur: tibia: tarsus of hindleg 1.2: 1.2: 1.0, tarsal segments 1–3 arranged in decreasing order as 3,1, 2.

Egg: Oval, with regular papillae ( Fig. 7I View FIGURE 7 ).

Diagnosis. The new species P. strumiferum sp. n. can be distinguished from congeners by the combination of the following diagnostic characters. Nymph: maxillary palpi two segmented, length ratio from base to apex 0.6: 1.0 ( Figs 4F View FIGURE 4 , 8C View FIGURE 8 ); gills I–V with double lamellae but gills VI–VII single ( Figs 9E–H View FIGURE 9 ); claw about 1/2 length of respective tarsus and widened at base ( Figs 6E–F View FIGURE 6 ).

Adults of P. strumiferum sp. n. have tiny hindwings, which have no costal projection or visible veins ( Fig. 1D View FIGURE 1 ). Forceps of males’ strumiferum are unique in having relatively widened segment I and elongated segment III ( Figs 3C, F View FIGURE 3 ). The color pattern of abdomen (terga with two reddish lines on posterior margins and terga IV with a pair of oblique stripes) is useful to identify both males and females ( Figs 2E–F View FIGURE 2 ).

Another species Procloeon albisternum (Novikova, 1986) (in Tshernova et al. 1986) also has two segmented maxillary palpi. But it can be differentiated from our new species P. strumiferum sp. n. by single gills IV in nymphal stage. In addition, the adults of it have costal projection of hindwings. In contrast, our new species has a long-oval hindwings, which has no projection.

Distribution. China (Jiangsu Province).

Etymology. The specific name of this species “ strumiferum ” (neutral) comes from Latin word “ strumifer ” (having tubercle), indicating the basal segment of male forceps with tubercle-like projections.