Notacanthurus maculatus Zhou, 2020

Zhang, Wei, Zhang, Min, Han, Na & Zhou, Chang-Fa, 2020, Two new species of the genus Notacanthurus from China (Ephemeroptera: Heptageniidae, Ecdyonurinae), Zootaxa 4802 (2), pp. 335-348 : 336-341

publication ID	https://doi.org/ 10.11646/zootaxa.4802.2.7
publication LSID	lsid:zoobank.org:pub:41E57AB6-CBA9-490A-9540-20DF787EAD3C
persistent identifier	https://treatment.plazi.org/id/03F3878E-FFD1-FFB5-63B9-0000FB1D6F8C
treatment provided by	Plazi
scientific name	Notacanthurus maculatus Zhou
status	sp. nov.

Treatment

Notacanthurus maculatus Zhou , sp. n.

Materials examined. Holotype: male imago (reared from mature nymph), Yue-Ba town (33°32′50.86″N, 107°49′29.36″E), Fo-Ping county , Han-Zhong city, Shaanxi Province, China, collected by Chang-Fa ZHOU, Qiang XIE, 25-VII-2000. GoogleMaps

Paratypes: 2 male imagoes 1 female imago 3 female subimagoes (reared from mature nymphs) 50 nymphs, same as the holotype; 1 male imago 3 female imagoes, Sai-Ke bridge (32°52′45.66″N, 104°24′22.36″E), Tie-Lou village, Wen county , Gansu Province, collected by Chang-Fa ZHOU, 8-VIII-2000 GoogleMaps ; 4 male imagoes 2 female imagoes 50 nymphs, Xi-Xia stream (32°52′45.66″N, 104°24′22.36″E), Xia-Chuan town, Jin-Cheng city, Shanxi Province, col- lected by Yan-Xia WANG GoogleMaps , Ze-Yu WANG, 23-VII-2012 ; 3 male imagoes 6 male subimagoes 4 female subimagoes 30 nymphs, Great-River village (35°44′23.90″N, 111°02′23.43″E), Yi-Cheng county, Lin-Fen city, Shanxi Prov- ince, collected by Chang-Hai SUN, Ji-Hua XU, Zi-Wei WANG, 13-IX-2013 GoogleMaps ; 2 male imagoes 1 female subimago 2 nymphs, Yang-Lin-Qiao town (30°44′52.44″N, 110°45′57.85″E), Yi-Chang county , Hubei Province, collected by Ran LI, Wei ZHANG, 2-VIII-2019 GoogleMaps .

Description. Nymph (in alcohol, Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 ): body length 9.0–13.0 mm, caudal filaments 13.0–15.0 mm (mean of 14 nymphs). Head width 1.4–1.8x of length, yellow brown to dark brown. Anterior margin of head not thickened; anterior and lateral margins slightly convex while posterior margin nearly straight; vertex with thin pale stripe above compound eyes ( Fig. 1 View FIGURE 1 A–B).

Mouthparts: labrum 0.5x width of head, laterally tapering and slightly curved, relatively long setae on dorsal surface and free margin, ventral surface with shallow median emargination and ventral groove, row of bristles along the margin of groove ( Fig. 2 View FIGURE 2 A–B). Both mandibles covered with numerous long setae on outer margins; prostheca with 4–6 fimbriate bristles; outer incisor of left mandible with serrated margin and one larger terminal denticle; inner one with trifid apex and row of sparse hair-like setae below the molar; outer incisor of right mandible serrated with 2 apical terminal denticles; inner one divided into 3 sharp denticles ( Fig. 2 View FIGURE 2 C–D, H–I). Maxillae with scattered simple setae on ventral surface, with 19–21 comb-shaped setae on crown of galea-lacinia, distal dentisetae branched, proximal dentisetae bifid and fimbriate ( Figs 2G View FIGURE 2 , 4 View FIGURE 4 A–C); maxillary palp 3-segmented, basal segment with sporadic setae on outer margin; outer margin of second segment with longer setae and terminal segment with dense setae brush ( Fig. 2G View FIGURE 2 ). Hypopharynx: apex of superlinguae strongly curved and extended into round lobe-like structure, row of hair-like setae on the outer margin from base to apex; lingua bell-like, with tuft of setae on apex ( Fig. 2E View FIGURE 2 ). Labium: glossae subquadrangular, inner margin of glossae slightly expanded, with tuft of long setae; paraglossae expanded into distinct lobes, with dense setae and bristles on dorsal and free margins; labial palp 2-segmented, ventral surface and free margin of second segment with setae brush, dorsal surface with scattered golden setae ( Fig. 2F View FIGURE 2 ).

Thorax: pronotum extended laterally, slightly wider than head ( Fig. 1 View FIGURE 1 A–B). Supracoxal spurs rounded. Legs yellowish with two brown bands on femora; ventral surface of femora with spots on middle and apex ( Figs 1 View FIGURE 1 A–C, 3A–C). Femora of all legs with row of long setae on outer margin, dorsal surface with scattered spatulate setae, apex of femora with blunt apical projection ( Fig. 3 View FIGURE 3 A–C, 3F); foretibiae subequal to femora in length, with rows of spinelike setae on inner and dorsal margins, outer margin with few tiny and short setae on base, foretarsi ca. half length of tibiae ( Fig. 3A View FIGURE 3 ); midlegs similar to forelegs, except tibiae 0.8x length of femora, with dense setae on outer margin, tarsi 1/3 length of tibiae ( Fig. 3B View FIGURE 3 ); hindlegs similar to midlegs except tibiae 0.77x length of femora and outer margin with denser setae, hindtarsi with row of hair-like setae on outer margin ( Fig. 3 View FIGURE 3 C–D). Claws of all legs similar, with a large basal denticle and 2 subapical denticles ( Fig. 3E View FIGURE 3 ).

Abdomen: abdominal terga I–IX each with median black dot on anterior margin and a longitudinal ridge, the ridge protrudes towards posterior of tergum, forming a spine; submedian part of terga I–IX each with pair of brown oblique stripes, an additional small pair of pale dots nearby ( Fig. 1A, 1C View FIGURE 1 ). Each tergum with row of small pointed spines on posterior margin and black stripe close to these spines ( Fig. 1A, 1C View FIGURE 1 ); posterolateral angles of terga I–VIII extended into small acute projections; posterior margin of sternum IX straight to slightly convex ( Fig. 1D View FIGURE 1 ), some mature nymphs washed with median dark brown stripes on sternum IX. Gills I–VI with both lamellae and fibrilliform portions and gill VII with lamellae only; gill I leaf-like, inner margin curved, lamellae longer than fibrilliform portion ( Fig. 3H View FIGURE 3 ); gills II–VI similar to each other, lamellae broad ( Fig. 3 View FIGURE 3 I–J); gills V–VI each with an additional arrow-like accessory lobe ( Fig. 3J View FIGURE 3 ); gill VII slightly asymmetrical, with fine marginal setae ( Fig. 3K View FIGURE 3 ). Terminal fila- ment subequal to cerci, all of them with whorls of spines on articulations ( Fig. 3G View FIGURE 3 ).

Male imago (in alcohol, Figs 5–6 View FIGURE 5 View FIGURE 6 ): body length 10.0–12.0 mm, forewing 10.0–13.0 mm, hindwing 4.0–5.0 mm, cerci 25.0–30.0 mm. Body pale to yellowish with brown dots and stripes; anterior margin of head capsule not greatly produced, compound eyes contiguous ( Fig. 5 View FIGURE 5 A–B). Mesonotum with apparent transverse suture, lateral parapsidal sutures slightly bent, joining posterior transverse suture ( Fig. 5B View FIGURE 5 ). Prosternum relatively flat; mesotho- racic furcasternum parallel ( Fig. 5C View FIGURE 5 ). Femora of all legs pale, with 3 brown bands; tibiae and tarsi pale with brown apex ( Fig. 5A View FIGURE 5 ). Femora: tibiae: tarsi of forelegs=3.0: 4.0: 6.4, tarsal segments from basal to apical=1.2: 2.0: 1.8: 1.0: 0.4; midlegs and hindlegs similar to forelegs except femora: tibiae: tarsi=3.2: 2.5: 1.4, tarsal segments arranged in decreasing order=5, 1, 2, 3, 4. Forewing hyaline, crossveins pigmented dark brown between C, Sc, R 1 and Rs; several crowded crossveins between Sc, R 1 and Rs; Rs and MP forked sub-equidistant from base of wing to margin, MA forked over 1/2 of distance from base of wing to margin ( Fig. 6A View FIGURE 6 ). Hindwing transparent, with basal costal projection, MA forked near middle but MP forked basally ( Fig. 6B View FIGURE 6 ). Each tergum of abdomen I–IX with median brown dots on anterior margin and pair of oblique brown stripes laterally ( Fig. 5D View FIGURE 5 ).

Genitalia: styliger plate almost straight with 2 small lateral projections ( Fig. 6D View FIGURE 6 ). Forceps segments 3–4 less than half length of segment 2, segment 4 oval, slightly shorter than segment 3. Penes fused but with apical incision and distinct brown spermatic duct on ventral surface, stem base of penes sclerotized laterally; with median spinelike titillators subapically and mesally ( Fig. 6 View FIGURE 6 D–E). Cerci pale with brown articulations ( Fig. 5A View FIGURE 5 ).

Male subimago (in alcohol): body length 10.0–12.0 mm, forewing 11.0–12.0 mm, hindwing 4.0–5.0 mm, caudal filaments 9.0–12.0 mm. Resembles the male imago except dull. Femora: tibiae: tarsi of forelegs=3.0: 2.8: 2.4, tarsal segments arranged in decreasing order=2, 3, 1, 4, 5; those of midlegs=3.0: 2.6: 1.2, tarsal segments arranged in decreasing order=5, 1, 2, 3, 4; those of hindlegs=3.2: 3.6: 1.2, tarsal segments similar to midlegs.

Female imago (in alcohol, Figs 5E View FIGURE 5 , 6C View FIGURE 6 ): body length 10.0–14.0 mm, caudal filaments 18.0–27.0 mm, forewing 12.0–15.0 mm, hindwing 4.0–5.0 mm. Similar to male imago except as follows: lengths of femora: tibiae: tarsi of forelegs=3.0: 3.2: 2.2, tarsal segments arranged in decreasing order=2, 3, 1, 4, 5; those of midlegs=3.6: 3.0: 1.4, length order of tarsal segments in decreasing order=5, 1, 2, 3, 4; those of hindlegs=4.0: 3.0: 1.4, tarsal segments similar to midlegs. Lateral stripes on abdomen terga reddish and much broader ( Fig. 5E View FIGURE 5 ). Subgenital plate almost close to posterior margin of sternum VIII; subanal plate with convex posterior margin ( Fig. 6C View FIGURE 6 ). Articulations of cerci brown to dark.

Female subimago (in alcohol): body length 10.0–12.0 mm, forewing 12.0–14.0 mm, hindwing 4.0–5.0 mm, caudal filaments 10.0–15.0 mm. Color pattern resembles female imago except dull. Femora: tibiae: tarsi of forelegs=3.0: 2.6: 2.4, tarsal segments arranged in decreasing order=2, 3, 5, 1, 4; those of midlegs=3.0: 2.4: 1.2, length order of tarsal segments in decreasing=5, 1, 2, 3, 4; those of hindlegs=3.2: 2.8: 1.2, tarsal segments similar to midlegs.

Egg ( Fig. 7 View FIGURE 7 ): Egg ovoid, chorion decorated with irregular tubercle-like projections and small knob-terminated coiled threads (KCTs) on polar ( Fig. 7A View FIGURE 7 ). Micropyle round to oval ( Fig. 7 View FIGURE 7 A–B).

Etymology: The Latin specific name maculatus means marks, spots or having spots. It indicates the nymphs of this species having more spots on both sides of femora.

Diagnosis. This species can be distinguished from others Notacanthurus by the following combination of characters. In nymph: 1) femora of all legs with ventral spots; 2) tibiae of mid- and hindleg with rows of spine-like setae on dorsal and inner margins; 3) claws with 2 subapical denticles; 4) gills V–VI with additional arrow-like lobes. In imagoes: 1) round penis lobes with visible spermatic duct and basal sclerites on ventral surface; 2) anterior margin of head not expanded; 3) posterior margin of subgenital plate almost reaching the tip of sternum VIII.

In the seven known species of the genus Notacanthurus , the nymph of N. maculatus sp. n. appears to be closely related to N. baei Braasch & Boonsoong (2009) because of their similar color patterns of abdominal terga, head capsule with nearly straight posterior margins, gills V–VI with accessory lobes and sternum IX with prospective median dark stripe. However, compared to N. baei , the nymph of N. maculatus sp. n. has larger body size (9.0–13.0 mm), head width more than 1.4 of length (1.4–1.8), a thin white stripe above compound eyes, pronotum slightly wider than head, posterior margin of sternum IX nearly straight. In contrast, the nymph of N. baei has smaller size (8.0–9.0 mm), head width 1.4 of length, head capsule with irregular pale yellow markings, pronotum slightly smaller than head, posterior margin of sternum IX with notch. In addition, the gills shape of them are also different; N. maculatus sp. n. has gill I leaf-like, lamellae of gills II–VII broad while N. baei has gill I knife-shaped, gills II–VII with narrower lamellae.

In adults, male and female imagoes of N. maculatus sp. n. have pigmented crossveins in fields of C, Sc, R 1 and Rs. In contrast to other congeners ( N. cristatus , N. ladakhensis and N. zhiltzovae ), N. maculatus sp. n. is unique by having unexpanded anterior margin of head capsule and simple teardrop shaped penis lobes.