Epeorus (Caucasiron) extraordinarius Chen, Wang & Zhou, 2010, sp. nov.
Creators: name: Chen, Ping
name: Wang, Yu-Yu
name: Zhou, Chang-Fa
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Heptageniidae
Epeorus
Epeorus extraordinarius

description: Epeorus (Caucasiron) extraordinarius sp. nov.
Nymph (in ethanol): body length 8.0–10. 0 mm, caudal filaments 13.0–15.0 mm. Head capsule yellowish brown dorsally but paler near anterior and lateral margins, upper portion of ocelli pale, basal portion dark. Anterior margin of head capsule evenly convex with row of dense setae; posterior lateral margins strongly narrowed giving a concave appearance to lateral margins, with maxillary palpi visibly projecting beyond margins in dorsal view (Figs. 1, 31–33), female capsule slightly rounder than male but their shape pattern similar (Fig. 35); posterior margin of capsule weakly convex, with submedian tufts of setae posterior to eyes (Figs. 1, 31, 33, 35). Labrum 0.25 as wide as head capsule, apical margin concave but without median emargination; ventral surface with setae, those near anterolateral margins longer; submedian bristles on dorsal surface (Figs. 2–3). Mandibles with tuft of bristles on inner margin (Figs. 4–5); outer incisor larger and stronger than inner incisor, margins serrated; ventral margin of inner incisor serrated; each incisor with a row of bristles on ventral margin; prostheca represented by a tuft of fine setae (Fig. 6). Maxillae without armature on crown of galea-lacinia, apex terminating in triad of stout canines; ventral surface with submedian row of setae and mesal margin with a row of dense setae, basal setae longer than others; maxillary palpi 2-segmented, basal segment expanded slightly; apex of apical segment acute, about 1. 2 X length of basal segment, with brush composed of dense small pectinate spines (Fig. 7); a row of sparse setae on dorsal surface (Fig. 8). Hypopharynx with lingua rounded at apex, lateral corner slightly projected into small lobes; superlinguae slightly expanded laterally, with dense row of setae at apex, lateral margins pigmented in purple or even dark (Fig. 10). Labium with U-shaped separation between glossae, paraglossae moderately expanded laterally, glossae and paraglossae with dense setae dorsally; apical segment of labial palpi subequal in length to basal segment, with subapical setae dorsally and a row of pectinate spines ventrally (Fig. 9).
Pro- and mesonota brown to dark brown, with irregular pale dots and stripes dorsally (Figs. 1, 31). Femora of all legs gray, with distinct dark median marking, base and apex of femora pigmented slightly darker; femora with row of long hair on dorsal margin interspersed with pectinate setae and small spine-like setae; femora surface with scattered, mostly spatulate setae (Figs. 11–14). Foretibiae slightly longer than forefemora, mid tibiae subequal to mid femora, and hind tibiae slightly shorter than hind femora; all tibiae and tarsi with a row of setae on dorsal margins (Figs. 11–13). Claws with 3–4 denticles (Fig. 15).
Abdominal terga 1–10 with median row of setae dorsally, 2 large pale submedian maculae occupying most of each tergum surrounded by dark area (Figs. 1, 31); a row of spines along posterior margins of terga (Figs. 1, 20); posterolateral portions of terga 2–7 elongated into 2 strong projections (Figs. 1, 16, 31–32). Sterna pale, sterna 2–9 with longitudinal reddish brown median band, band paler on sternum 1 (Figs. 16, 32). Gills on abdominal segments 1–7; gills 1 with outer margins and basal area of inner margin weakly sclerotized, outer margin and ventral surface covered with dense setae; lamellae enlarged and expanded anteriorly to overlay each other beneath mesothorax; fibrilliform portion absent (Figs. 16, 32). Gills 2–6 similar in shape and structure but progressively smaller posteriorly, lamellae of each gill with fibrilliform portions, fibrilliform threads progressively fewer posteriorly (Figs. 18, 32). Gills 7 similar to gills 2–6 in structure but smaller, lamellae folded (Figs. 19, 32). Cerci with dorsal setae on several basal segments, articulations of cerci with very small spines (Figs. 1, 21, 31).
Male imago (in ethanol): body length 11. 0 mm, forewing 12. 5 mm, hindwing 4. 5 mm, foreleg 13. 0 mm, mid leg 6. 6 mm, hind leg 7. 4mm, cerci 36. 0 mm. Body purple-brown to dark, with various pale dots and stripes. Vertex of head dark brown, basal half of compound eyes dark, apical half pale. Eyes occupying most of head, dorsally eyes not contiguous, distance between eyes less than width of median ocellus. Thorax dark brown. Wings transparent but stigma area semi-hyaline. Veins of hind wings thinner than those of forewing (Figs. 22–23). Forelegs: ratios of femora: tibiae: tarsi = 3:4:6, order of tarsal segments arranged in descending length 1, 2, 3, 4, 5, basal segment slightly longer than second; femora pale brown, with median and apical dark markings; tibiae dark brown; basal segment of tarsi slighter darker than others (Fig. 24). Mid legs: ratios of femora: tibiae: tarsi =2. 6: 2. 2:1. 8, order of tarsal segments arranged in descending length 1, 2, 5, 3, 4 (Fig. 25). Hind legs: ratios of femora: tibiae: tarsi = 2. 8: 2. 6:2. 0, order of tarsal segments arranged in descending length 1, 2, 5, 3, 4 (Fig. 26). Color pattern of mid legs and hind legs similar to forelegs but much paler. Claws of all legs dissimilar: one blunt, pad-like; other apically hooked (Figs. 24–26).
Genitalia (Figs. 28–29, 34): Styliger plate with convex posterior margin. Forceps segment 1 very short, segment 2 long, combined length of segment 3–4 subequal to half of segment 2. Penes fused at base and divergent in apical half, ventral surface sclerotised, each penis lobe with a small, distinct titillator.
Female (in ethanol): Body length 11. 0 mm, forewings 15. 0 mm, hind wings 5. 0 mm, cerci 30. 0 mm. Length of femora, tibiae and tarsi of midlegs = 3. 0, 2. 2 and 1. 8, ratio of hind legs = 3. 0, 2. 5 and 2. 0 [fore legs broken off and missing]. Body color pattern similar to that of male but much paler (Fig. 38). Posterior margin of sternum 7 expanded and extended to posterior margin of sternum 8, apex of sternum 9 extended slightly, shallowly concave, color pattern as in Fig. 30 and Fig. 39.
Male subimago (in ethanol): Body length 10. 0 mm, forewings 12. 0 mm, hind wings 4. 0 mm, cerci 15. 0, Length ratio of femora, tibiae and tarsi of forelegs = 2. 0, 3. 0 and 2. 2, length ratio of mid legs = 3. 0, 2. 2 and 1. 8, and that of hind legs = 3. 0, 2. 5 and 2. 0. Body color pattern as in male imago but much paler. Wings opaque, crossveins circled with dark pigments.
Etymology. The epithet extraordinarius (adjective, means strange, outstanding) is from the Latin, in reference to the nymphal some unique head capsule.
Discussion and diagnosis. To date, 12 species have been placed in the subgenus: E. (C.) alpestris (Braasch, 1979) (nymph and imago), E. (C.) caucasicus (Tshernova, 1938) (imago and nymph), E. (C.) fuscus (Sinitshenkova, 1976) (nymph), E. (C.) guttatus (Braasch & Soldán, 1979) (nymph and imago), E. (C.) insularis (Braasch, 1983) (imago), E. (C.) longimaculatus (Braasch, 1980) (nymph and subimago), E. (C.) magnus (Braasch. 1978) (nymph and imago), E. (C.) nigripilosus (Sinitshenkova, 1976) (nymph and imago), E. (C.) paraguttatus (Braasch, 1983) (nymph and imago), E. (C.) sinitshenkovae (Braasch & Zimmermann, 1979) (nymph and imago), E. (C.) soldani (Braasch, 1979) (nymph and imago), E. (C.) znojkoi (Tshernova, 1938) (nymph and imago) (Braasch 1978, 1979, 1980, 1981, 1983a-b, 2006a; Braasch & Soldan 1979; Braasch & Zimmermann 1979; Sinitshenkova 1976; Tshernova 1938). In addition, the species Iron suspicatus Braasch (2006) seems to belong to this subgenus based on figures and description (Braasch 2006b).
E. (C.) extraordinarius sp. nov. can be distinguished from all described species of Epeorus (Caucasiron) by the following combination of characters. In the imago, 1) presence of dark macula on all femora; 2) broad, median reddish band on abdominal sterna 1–9, divergent on sternum 9 of female (Figs. 30, 37, 39), and 3) short titillators on penes (Figs. 28, 29, 34). In the nymph, 1) presence of dark macula on all femora; 2) head capsule broadly expanded apically with lateral concavity in males and females (although concavity weaker in females); 3) gills 1 without fibrilliform threads (Fig. 17); 4) protuberance in basal third of gills 2–6 (Figs. 18, 19, 32), and 5) claws with 3–4 small denticles. The dorsal color pattern of abdomen and the presence of setal tufts posterior to the eyes would also appear to characterize the new species, but this suggestion is based only on published figures and the setae may have been previously overlooked.
E. (C.) extraordinarius sp. nov. looks like E. (C.) alpestris, E. (C.) caucasicus, E. (C.) nigripilosus and E. (C.) sinitshenkovae because of similar nymphal head capsules and imaginal color patterns. But the males of E. (C.) caucasicus, E. (C.) nigripilosus and E. (C.) sinitshenkovae have stronger titillators and no broad pigmented band on ventral surface of nymphal abdomens.
E. (C.) extraordinarius sp. nov. appears most similar to E. (C.) alpestris. But the nymphs of the latter species have a weakly concave lateral margin of head capsule. The males of E. (C.) alpestris have pigmented stripes or spots on sterna 1–8, while the males of E. (C.) extraordinarius sp. nov. have a broad pigmented band on sterna 1–9.
description: Published as part of Chen, Ping, Wang, Yu-Yu & Zhou, Chang-Fa, 2010, A New Mayfly Species of Epeorus (Caucasiron) from Southwestern China (Ephemeroptera: Heptageniidae), pp. 61-68 in Zootaxa 2527 on pages 62-67, DOI: 10.5281/zenodo.196454