Afronurus drepanophyllus, Zhang & Lei & Zhou, 2021

Zhang, Wei, Lei, Zhi-Ming, Li, Wen-Juan & Zhou, Chang-Fa, 2021, A contribution to the genus Afronurus Lestage, 1924 in China (Ephemeroptera: Heptageniidae, Ecdyonurinae), European Journal of Taxonomy 767 (1), pp. 94-116 : 96-100

Afronurus drepanophyllus sp. nov.

urn:lsid:zoobank.org:act:8B78F047-E8D6-4149-9A2E-10D631959037

Figs 1–3 , 4A, D , 5 , 6A

Diagnosis

Compared to the other five Chinese Afronurus species , this new species somewhat resembles A. furcatus , A. hunanensis and A. yixingensis in imaginal stages because of their similar abdominal color patterns (with longitudinal stripes and pale dots submedially). However, these species can easily be differentiated from each other by the shape of the penes and titillators: penial lobes of A. drepanophyllus sp. nov. are obviously divergent and form a U-shaped cleft; apex of each penis diverges into three lobes; titillators are thicker and stronger than in other congeners ( Fig. 5D–E ). Comparatively, A. yixingensis has a spinelike projection between the two penial lobes and divergent spine-like titillators ( Fig. 13I–J ), while A. furcatus and A. hunanensis have plate-like titillators. Furthermore, the penial lobes of A. furcatus are slightly divergent and connected by a foliated structure ( Fig. 13A–B ). In contrast, A. hunanensis has penial lobes obviously spread out and U-shaped deeply cleft ( Fig. 13C–D ).

Generally, the nymphs of the six Chinese Afronurus species are alike because of their yellowishbrown body with various pale dots or stripes. For the convenience of identification, we separate them into two groups here: anterior margin of head with pale dots ( A. drepanophyllus sp. nov., A. furcatus , A. obliquistriatus and A. rubromaculatus ) ( Figs 1A , 7A, G, J ) and without any dot ( A. hunanensis and A. yixingensis ) ( Fig. 7D, M ) (for detailed comparisons see remarks of each species below). Among the first group, A. drepanophyllus sp. nov. and A. furcatus can be identified by the following characters: 1) glossae of the new species are slightly oblong ( Fig. 2F ), by contrast, glossae of A. furcatus are lobe-like ( Fig. 8E ); 2) gill I is sickle-like in the new species ( Fig. 3F ) but banana-shaped in A. furcatus ( Fig. 9F ).

Compared to other Asian congeners in the genus, this new species appears to be closely related to the Thailand species A. namnaoensis Braasch & Boonsoong, 2010 in both nymphal and imaginal stages, e.g., the structures of mouthparts, legs and the shape of genitalia. However, the nymph of A. drepanophyllus sp. nov. has larger body size (6.0–8.0 mm); head capsule has 2–5 pale dots on anterior margin and 4–5 pale dots on posterior margin, respectively; abdominal terga yellowish brown and with marked pale dots on terga I–IX; gill I sickle-like; caudal filaments slightly longer than body. In contrast, the nymph of A. namnaoensis has smaller body size (4.5–6.1 mm); head capsule without distinct dot; terga yellowish and with light markings on terga VII–IX; gill I leaf-like; caudal filaments 2× length of body. In male imago, A. drepanophyllus sp. nov. has larger body size (8.0–10.0 mm); abdominal terga I–IX with brown longitudinal stripe and a pair of small pale dots medially; styliger plate with projections laterally; forceps with segment III subequal in length to segment IV and combined segments III and IV about half of segment II. Comparatively, A. namnaoensis has smaller body size (6.2–6.9 mm); terga I–IX with median stripe only; lateral margins of styliger plate slightly expanded; forceps with segment IV half of segment III in length and combined segments III and IV ⅓× length of segment II.

Etymology

The Latin specific name ‘ drepanophyllus ’ means ‘sickle’. It indicates the nymphs having sickle-like gills I.

Material examined

Holotype CHINA • ♂; Yunnan Province, Meng-La County, Meng-Lun town ; 21°56′7.12″ N, 101°14′55.72″ E; alt. 683 m; 22 Jan. 2019; X.H.Y. Zheng leg.; NNU.

Paratypes CHINA • 1 ♂, 1 ♂ subimago, 1 ♀, 4 nymphs; same collection data as for holotype; NNU .

Additional material

CHINA • 2 ♂♂, 50 nymphs; Yunnan Province, Liang-He County, Fen-Shui-Ling town ; 24°46′44.11″ N, 98°16′5.92″ E; alt. 951 m; 26 Apr. 2018; W. Zhang and Z.X. Ma leg.; NNU .

Description

Nymph

MEASUREMENTS. Body length 6.0–8.0 mm, caudal filaments 8.0–10.0 mm long.

COLORATION. Body yellowish-brown to brown.

HEAD. Head capsule subquadrangular, anterior margin slightly thickened and with 2–5 small pale dots (some immature individuals less than 5 dots), posterior margin slightly concave; additional 4–5 pale dots located between compound eyes ( Fig. 1A ). Labrum expanded laterally, with slightly rounded apices; anterior margin with shallow median groove, long and dense setae on dorsal and ventral surfaces, those on dorsal surface longer and denser than others ( Fig. 2A–B ); an additional row of short bristles on ventral anterior margin ( Fig. 2B ). Both mandibles covered with numerous setae on outer margins; prostheca with 3–5 fimbriate bristles ( Fig. 2D–E, H–I ); outer incisor of left mandible with serrated margin and one larger terminal denticle; inner incisor shorter than outer incisor and with trifid apex ( Fig. 2D, H ); outer incisor of right mandible serrated and with 2 apical terminal denticles; inner one divided into 2 sharp denticles ( Fig. 2E, I ). Hypopharynx: apex of superlinguae strongly curved and extended into round lobelike structures, row of long hair-like setae on lateral margins from base to apex; lingua bell-like, subequal to superlinguae in length and with tuft of setae at apex ( Fig. 2C ). Maxillae with scattered fimbriate setae on ventral surface ( Figs 2G , 4D ), row of 13–15 comb-shaped setae on crown of galea-lacinia, middle combs with 9–13 teeth, distal dentisetae branched, proximal dentisetae bifid and fringed ( Fig. 4A ); maxillary palpi 3-segmented, first segment with setae on outer margin and basal half of inner margin; second segment obviously longer than basal one, outer margin with long setae, terminal segment with dense setaceous brush ( Fig. 2G ). Labium: slightly oblong, inner margins of glossae slightly expanded and with tuft of long setae; paraglossae expanded greatly into palpable lobes, with dense setae and bristles on dorsal and anterior margins; labial palpi broad, 2-segmented; ventral surface and free margin with setae brushes; dorsal surface with setae ( Fig. 2F ).

THORAX. Pronotum slightly extended laterally, subequal to head in width ( Fig. 1A–B ). Supracoxal spurs rounded. Femora of all legs with long setae on outer margins, dorsal surfaces and inner margins with two kinds of spatulate setae, the shorter setae more abundant than longer ones ( Fig. 3J ). Foretibia subequal in length to femur, base of outer margin with sparse hair-like setae ( Fig. 3A ), dorsal surface with rows of fine setae and bristles, inner margin with row of bristles only; foretarsi slightly shorter than ⅓ tibia, outer and inner margins with tiny setae. Midleg similar to foreleg, except tibia 0.7× length of femur, with row of hair-like setae on outer margin ( Fig. 3B ). Hindleg similar to midleg except tibia 0.65× length of femur, outer margin with rows of dense hair-like setae and bristles, dorsal surface with short and long bristles ( Fig. 3C–D ). Claws of all legs with 3–4 subapical denticles ( Fig. 3E ).

ABDOMEN. Abdominal terga I–II pale, terga III–VII brown with 2 median pale dots and 2 lateral dots; pale dots on terga IV–V fused together and forming pale stripes; terga VIII–IX with fused pale dots and tergum VIII always with longitudinal brown stripe medially; tergum X dark brown ( Fig. 1A ); posterolateral angles of terga III–VII extended into small acute projections. Gill I sickle-like, inner margin slightly curved ( Fig. 3F ); gills II–VI heart-like and lamellae expanded laterally ( Fig. 3G ), gills V–VI with apical arrow-like accessory lobes ( Fig. 3H ); gill VII round, with fine marginal setae, appreciably asymmetrical ( Fig. 3I ). Basal of caudal filaments pale and other parts yellowish brown, with whorled spines on articulations ( Fig. 1A–B ).

Male imago

MEASUREMENTS. Body length 8.0–10.0 mm, forewing 8.0–10.0 mm, hindwing 2.0–3.0 mm, cerci 19.0– 22.0 mm long. Compound eyes contiguous, upper portion hoar and lower portion dark blue.

COLORATION. Body generally pale to yellowish ( Fig. 5A, 5F ).

THORAX. Mesonotum with apparent transverse suture, and medial depression of furcasternum parallel. Foreleg: length of femur 3.0 mm, length of tibia 3.5 mm, length of tarsi 4.5 mm, tarsal segments from basal to apical = 0.9:1.4:1.2:0.6:0.4. Midleg: length of femur 2.0 mm, length of tibia 1.3 mm, length of tarsi 1.0 mm, tarsal segments arranged in decreasing order as 1, 5, 2, 3, 4. Hindleg: length of femur 2.0 mm, length of tibia 1.5 mm, length of tarsi 0.8 mm, tarsal segments arranged in decreasing order as 5, 1, 2, 3, 4. All claws of legs similar, one blunt and one hooked. Forewing hyaline, costal, subcostal and R 1 fields semitransparent; Rs and MP forked at same level at wing base, MA forked at over ½ of distance from base of wing to margin ( Fig. 5B ). Hindwing transparent, with costal projection at base, MA forked in middle, MP forked much more basally than MA ( Fig. 5C ).

ABDOMEN. Pale but with a longitudinal light brown stripe medially, terga I–VII with pair of pale dots, posterior margin of each tergum with dark brown stripe ( Fig. 5F ).

GENITALIA. Posterior margin of styliger plate convex, lateral margins with two distinct lobes ( Fig. 5D– E ). Forceps of segment III subequal to those of segment IV in length, combined segments III–IV approximately half length of segment II. Penial lobes divergent and with U-shaped cleft between them; apices of penial lobes divided into three parts or apices, the median one much broader than inner and outer lobes. Robust but blunt titillators at base of penes, covered by styliger plate and invisible in ventral view ( Fig. 5D–E ). Cerci pale with dense tiny setae on surface and brown dots on articulations.

Egg

Oval, chorion decorated with small KCTs at poles, large KCTs located equatorially ( Fig. 6A ).

Distribution

China (Yunnan, Guizhou, Zhejiang, Guangxi).

Figures

Fig. 1. Nymph of Afronurus drepanophyllus sp. nov. (NNU).A. Nymphal habitus. B. Selected segments, enlarged, of terminal filament and right cercus (dorsal view). Scale bars: A = 2.0 mm; B = 0.1 mm.

Fig. 2. Mouthparts of Afronurus drepanophyllus sp. nov. (NNU). A. Labrum (ventral view). B. Median bristles of ventral labrum. C. Hypopharynx (ventral view). D. Left mandible (ventral view). E. Right mandible (ventral view). F. Labium. G. Maxillae. H. Incisors of left mandible. I. Incisors of right mandible. Scale bars: A, C–G = 0.5 mm; B = 0.3 mm; H–I = 0.2 mm.

Fig. 3. Nymphal structures of Afronurus drepanophyllus sp. nov. (NNU). A. Foreleg. B. Midleg. C. Hindleg. D. Hindleg tibia. E. Foreleg claw. F. Gill I. G. Gill II. H. Gill VI. I. Gill VII. J. Foreleg femur, bristles on dorsal surface. Scale bars: A–C = 1.0 mm; D, F, H = 0.5 mm; E, G = 0.3 mm; I = 0.2 mm; J = 0.1 mm.

Fig. 4. SEM photos of nymphal maxillae. A. A. drepanophyllus sp. nov. (NNU). B. A. furcatus (Zhou & Zheng, 2003) (NNU). C. A. hunanensis (Zhang & Cai, 1991) (NNU). A–C. Dentisetae. D. Enlarged scattered setae on ventral surface; the three species have similar structures (labels show distal dentisetae and proximal dentisetae respectively). Abbreviations: see Material and methods.

Fig. 5. Male structures of Afronurus drepanophyllus sp. nov. (NNU). A. Male imago habitus. B. Forewing. C. Hindwing. D. Genitalia. E. Penes enlarged (arrows show lobe on lateral margin and titillators, respectively). F. Male imago, showing abdominal terga. Scale bars: A = 5.0 mm; B–D = 1.0 mm; E = 0.2 mm; F = 2.0 mm.

Fig. 6. SEM photos of eggs. A. Afronurus drepanophyllus sp. nov. (NNU). B. A. furcatus (Zhou & Zheng, 2003) (NNU). C. A. hunanensis (Zhang & Cai, 1991) (NNU). D. A. obliquistriatus (You et al., 1981) (NNU). E. A. rubromaculatus (You et al., 1981) (NNU). F. A. yixingensis (Wu & You, 1986) (NNU).

Fig. 13. Genitalia of five species of Afronurus Lestage, 1924. A–B. A. furcatus (Zhou & Zheng, 2003) (NNU). C–D. A. hunanensis (Zhang & Cai, 1991) (NNU). E–F. A. obliquistriatus (You et al., 1981) (NNU). G–H. A. rubromaculatus (You et al., 1981) (NNU). I–J. A. yixingensis (Wu & You, 1986) (NNU). A, C, E, G, I. Genitalia. B, D, F, H, J. Penes enlarged; arrows show titillators. Scale bars: A, C, E, G, I = 0.5 mm; B, D, F, H, J = 0.2 mm.

Fig. 7. Nymphal habitus of five species of Afronurus Lestage, 1924. A–C. A. furcatus (Zhou & Zheng, 2003) (NNU). D–F. A. hunanensis (Zhang & Cai, 1991) (NNU). G–I. A. obliquistriatus (You et al., 1981) (NNU). J–L. A. rubromaculatus (You et al., 1981) (NNU). M–O. A. yixingensis (Wu & You, 1986) (NNU). A, D, G, J, M. Head capsule. B, E, H, K, N. Abdominal terga. C, F, I, L, O. Caudal filaments. Scale bars: A–B, D–E, G–H, J–K, M–N = 2.0 mm; C, F, I, L, O = 1.0 mm.

Fig. 8. Mouthparts of Afronurus furcatus (Zhou & Zheng, 2003) (NNU). A. Labrum (ventral view). B. Hypopharynx (ventral view). C. Left mandible (ventral view). D. Right mandible (ventral view). E. Labium. F. Maxillae. G. Incisors of left mandible. H. Incisors of right mandible. Scale bars: A, C–D, F = 0.5 mm; B = 0.3 mm; E = 1.0 mm; G–H = 0.1 mm.

Fig. 9. Nymphal structures of Afronurus furcatus (Zhou & Zheng, 2003) (NNU). A. Foreleg. B. Midleg. C. Hindleg. D. Hindleg tibia. E. Foreleg claw. F. Gill I. G. Gill II. H. Gill VI. I. Gill VII. Scale bars: A–D = 1.0 mm; E–I = 0.3 mm.