Siphlonurus polyspineus, Qiang & Zhou, 2025

Qiang, Xin-He & Zhou, Chang-Fa, 2025, The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae), Zootaxa 5711 (1), pp. 1-56 : 33-41

publication ID	https://doi.org/10.11646/zootaxa.5711.1.1
publication LSID	lsid:zoobank.org:pub:3178B789-303D-448B-9624-6423117DE14F
persistent identifier	https://treatment.plazi.org/id/E57D87B7-FFD0-FFDB-FF71-FF2D7E32FA30
treatment provided by	Plazi
scientific name	Siphlonurus polyspineus
status	sp. nov.

Treatment

Siphlonurus polyspineus sp. nov.

urn:lsid:zoobank.org:act:

Figures 20–26 View FIGURE 20 View FIGURE 21 View FIGURE 22 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26

Material examined

Holotype: male imago, Laocaohe, Mohe City, Daxinganling District , Heilongjiang Province, 52.833392°N, 122.591656°E, ca. 480m, 16–19.VII. 2024, Xinhe Qiang, Ningning Wang and Yuxian Sun. GoogleMaps

Paratypes: 5 nymphs, 8♀ imagos, 2♂ imagos, 2♀ subimagos, 3♂ subimagos, with same label data as holotype GoogleMaps .

Additional materials: 10 ♀ imagos, 3♂ imagos, Yalu River, Bugt Town, Yakeshi City , Inner Mongolia, 48.44625°N, 121.54724°E, ca. 670 m, 2.VIII.2007, Changfa Zhou, Hui Xie, and Shilei Wang GoogleMaps ; 15 ♀ imagos, Chaor River, Tarqi Town, Yakeshan City , Inner Mongolia, 47.58584°N, 121.11288°E, ca. 760 m, 3.VIII.2007, Changfa Zhou, Hui Xie, and Shilei Wang; 50 nymphs GoogleMaps , 20 ♀ imagos, Gen River, Genhe City , Inner Mongolia, 50.46255°N, 121.31191°E, ca. 700 m, 9–10.VIII.2007, Changfa Zhou, Hui Xie, and Shilei Wang GoogleMaps ; 2♀ imagos, Genhe, Hexi Street, Genhe City , Hulunbuir City , Inner Mongolia Autonomous Region , 50.796106°N, 121.578682°E, ca. 720 m, 19.VII.2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun GoogleMaps .

Description

Mature nymph (in alcohol, Figs 20–22 View FIGURE 20 View FIGURE 21 View FIGURE 22 ):

Body length 11.0–13.0 mm, cerci 5.0–6.0 mm, length of terminal filament nearly subequal to cerci. Body generally yellowish to amber, legs with distinct dark brown bands ( Figs 20A, B View FIGURE 20 ).

Head: generally yellowish with pair of longitudinal dark brown stripe on vertex. Clypeus dark brown. Compound eyes dark grey. Antennae 1.0 mm, length of antennae subequal to length of head.

Mouthparts: totally yellowish. Galea-lacinia and apical segment of maxillary palp dark brown. Labrum: free margin with row of dense bristle-like setae, additional row of setae near anterior margin dorsally. Ventral surface scattered with short dense bristle-like setae, forming an obvious median groove. Posterolateral corner slightly sclerotized. Length-to-width ratio about 1.0: 2.0 ( Fig. 21A View FIGURE 21 ). Left mandible: apex of outer incisor divided into three denticles and inner one divided into two denticles, outer incisor wider than inner one. Prostheca composed of distinct stout spine and a tuft of numerous spines ( Fig. 21B View FIGURE 21 ). Right mandible: apex of outer and inner incisors serrated into two denticles respectively. Prostheca constituted by tuft of spines and small spine. An additional tuft of hair-like setae on inner margin near molar ( Fig. 21C View FIGURE 21 ). Lingua of Hypopharynx round, apical surface with dense short setae. Superlinguae with hair-like setae on apical and lateral margins ( Fig. 21D View FIGURE 21 ). Maxillae: Apex of galea-lacinia divided into three broad canines.Apical margin of galea-lacinia with row of long setae. Inner margin with two rows of dense long setae and three stout apical dentisetae between them, two obvious dentisetae slightly longer than setae nearby. Three segments of maxillary palp with sparse setae on surface. Length of basal segment distinctly subequal to length of galea-lacinia, inner margin of maxillary palp segment II straight, length ratio of three segments ca. 1.0: 0.8: 0.5 ( Figs 21E, F View FIGURE 21 ). Labium: glossae and paraglossae with dense bristle-like setae on surface, paraglossae semi-circle and broader than glossae. Three segments of labial palp with sparse setae and spines on surface, inner margin of segment III slightly concave, length ratio of three segments from basal to apical ca. 1.0: 0.6: 0.5 ( Figs 21G, H View FIGURE 21 ).

Thorax: nota totally yellowish with symmetric irregular variable spots, wingpads without spots ( Fig. 20A View FIGURE 20 ). Coloration pattern of all legs similar, ground color yellowish, tarsi dark apically and basally. Surface of all legs with short sparse spines and setae ( Figs 22A–C View FIGURE 22 ). Claws slim and pointed, without teeth ( Fig. 22D View FIGURE 22 ). Length ratio of femora: tibiae: tarsus in all legs similar, ca. 1.7: 1.0: 1.1.

Abdomen: Each abdominal terga with pair of dark spots in middle. Each sternum with inverted U-shaped marking ( Fig. 20B View FIGURE 20 ). Posterolateral projection of each tergum well developed, progressively larger and wider from tergum I to tergum IX, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 ( Figs 20C–E View FIGURE 20 ). Abdominal sternum IX of both sexes with slightly convex posterior margin ( Figs 20D, E View FIGURE 20 ). Dorsal surface and posterior margins of abdominal terga I–IX covered with stout spine-like setae, while ventral surface and posterior margins of abdominal sterna I–IX with smaller, more sparse spine-like setae ( Figs 20A–B View FIGURE 20 ). Dorsal surface and posterior margin of tergum X with sparse stout and pointed spine-like setae; lateral margins lack ( Fig. 20F View FIGURE 20 ). Gills transparent and with distinct brown trachea, dorsal lamellae of gills I and II, along with the other five gills, with sclerotized ribs on the anterior margin and near the middle ( Figs 22E–K View FIGURE 22 ). Gills I and II similar in size and shape, outer margins of dorsal and ventral lamellae of both gills I and II concave. Costal rib of dorsal lamella in gill II shorter than half of anterior margin ( Figs 22E, F View FIGURE 22 ). Outer and posterior margins of gill III concave. Proximal plate of gill VII poorly developed ( Figs 22G, K View FIGURE 22 ). Caudal filaments yellowish with two dark brown band subapically and apically. Mesal margins of cerci and both sides of terminal filament with dense hair-like setae ( Fig. 20A, B View FIGURE 20 ).

Male imago (in alcohol, Figs 23–24 View FIGURE 23 View FIGURE 24 ): body length 13.0–15.0 mm, cerci 13.0–15.0 mm, terminal filament 0.1 mm, forewing 9.0–10.0 mm, hindwing 4.0–5.0 mm, antennae 0.8 mm. General coloration brown and amber, wings transparent ( Figs 23A–C View FIGURE 23 ). Head: Compound eyes contiguous and grey, ocelli pale with dark base. Antennae light brown with darker scape and pedicle. Thorax: general coloration dark brown. Posterior projection of mesonotum and metanotum distinctly convex ( Fig. 23A View FIGURE 23 ). Wings: transparent. In forewing, Rs forked at 1/3 basal, MA forked near middle, MP forked at very base, near the forking point of Rs and MA. Rs and MA fused near base, stem of them further fused with MP. CuA slightly curved backwards, ended at outer margin before tornus, six small veins connecting CuA to hind margin. CuP attached at midpoint of hind margin. In hindwing, MA forked at apical 1/3, MP forked at basal 1/3 ( Figs 23B, C View FIGURE 23 ). Legs: coxae of all legs dark brown, all legs generally whitish, without distinct markings. Each leg with two claws, acute and hooked ( Figs 24A–D View FIGURE 24 ). Length ratio of femur, tibia and tarsal segments I–V of foreleg = 3.6: 3.4: 1.4: 2.2: 2.1: 1.3: 1.0; length ratio of midleg = 12.5: 10.5: 3.0: 3.0: 2.0: 1.0: 3.3; length ratio of hindleg = 13.0: 10.0: 3.3: 3.0: 1.7: 1.0: 3.1. Abdomen: Each tergum dark laterally, each abdominal sternum with an inverted U-shaped marking ( Figs 23D, E View FIGURE 23 ). Posterolateral spines of abdominal segments VIII and IX relatively small ( Figs 24E, F View FIGURE 24 ). Genitalia: Posterior margin of styliger slightly convex. Four segments of forceps uniformly light brown, length ratio of them from basal to apical = 1.5: 2.8: 1.0: 1.0. Inner margin of basal segment of forceps with projection, length of penis longer than styliger ( Figs 24E, F View FIGURE 24 ). Dorsal elongation of penis short, blunt, and spineless, dorsal sclerotized transverse band of penis expanded in the middle, inner margin of each penis lobe with approximately 12 small spines, outer margin with approximately 7 serrated small spines. Each penis lobe with a slender and sharp projection posterolaterally and a translucent membranous structure ventrally ( Figs 24G–J View FIGURE 24 ). Cerci light brown.

Female imago (in alcohol, Fig. 25 View FIGURE 25 ):

Body length 14.0–16.0 mm, cerci 13.0–15.0 mm, terminal filament 0.1 mm, forewings 8.0–10.0 mm, hindwings 4.0–5.0 mm. Length ratio of forefemur: foretibia: foretarsal segments I–V = 7.0: 6.8: 2.6: 2.0: 2.0: 1.0: 1.6; length ratio of midleg = 10.8: 8.3: 3.0: 2.3: 1.7: 1.0: 2.3; length ratio of hindleg= 5.5: 3.3: 2.1: 1.6: 1.3: 1.2: 1.0. Color pattern of female similar to male, body dark brown, legs light brown. Wings transparent and veins clearer than in males ( Figs 25A–E View FIGURE 25 ). Each tergum dark brown laterally. Each sternum brown with lighter posterior margin. Posterolateral spines of terga VIII and IX invisible ( Figs 25B, C View FIGURE 25 ). Sternum VII extended posteriorly into trapezoidal lobe, subanal plate distinctly convex. Abdominal sternum VIII with pair of dark brown, funnel-like sclerotized stripes ( Fig. 25F View FIGURE 25 ).

Egg: generally oval ( Fig. 26A View FIGURE 26 ). Surface nearly smooth ( Fig. 26B View FIGURE 26 ).

Etymology: Due to penis lobe of this species being notably spiny, with approximately 12 small spines near inner margin, it is named ‘ polyspineus ’ here. This specific name combines two words: poly - (multiple) and spineus (spine, small spine).

Biology: This species is sympatric with S. chankae , S. lacustris , S. palaearcticus , and S. zhelochovtsevi , all collected in the same batch from the Laocaohe in Mohe City, Heilongjiang Province. These species inhabit small, slow-flowing pools near the banks of streams.

Distribution: China ( Heilongjiang Province, Inner Mongolia Autonomous Region).

Diagnosis: S. polyspineus sp. nov. can be distinguished from other species by following characters.

Nymph: (1) body relatively smaller than others, from 11.0 to 13.0 mm; (2) wingpads without spots ( Figs 20A, B View FIGURE 20 ); (3) Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II straight ( Fig. 21E View FIGURE 21 ); (4) length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 ( Figs 20C–E View FIGURE 20 ); (5) each abdominal sternum with an inverted “U”-shaped marking ( Fig. 20B View FIGURE 20 ); (6) posterior margin of abdominal sternum IX slightly convex ( Figs 20D, E View FIGURE 20 ); (7) dorsal surface and posterior margin of tergum X has sparse stout and pointed spine-like setae, lateral margins lack ( Fig. 20F View FIGURE 20 ); (8) outer margins of dorsal and ventral lamellae of both gills I and II concave; costal rib of dorsal lamella in gill II shorter than half of anterior margin ( Figs 22E, F View FIGURE 22 ); outer and posterior margins of gill III concave, proximal plate of gill VII poorly developed ( Figs 22G, K View FIGURE 22 ).

Male imago: (1) smaller body, from 13.0 to 15.0 mm; (2) wings transparent; (3) all legs generally whitish, without distinct marking ( Figs 23A–C View FIGURE 23 ); (4) each abdominal sternum with an inverted U-shaped marking ( Fig. 23D View FIGURE 23 ); (5) posterolateral spines of abdominal segments VIII and IX relatively small ( Figs 24E, F View FIGURE 24 ); inner margin of basal segment of forceps with projection, length of penis longer than styliger ( Figs 24E, F View FIGURE 24 ); (6) dorsal elongation of penis short, blunt, and spineless, dorsal sclerotized transverse band of penis expanded in the middle; inner margin with approximately 12 small spines, outer margin with approximately 7 serrated small spines, each penis lobe with a slender and sharp projection posterolaterally ( Figs 24G–J View FIGURE 24 ).

Female imago: (1) body length 14.0–16.0 mm; (2) wings transparent; (3) sternum VII extended posteriorly into a trapezoidal lobe; (4) sternum VIII with a pair of dark brown, funnel-like sclerotized stripes ( Fig. 25F View FIGURE 25 ).

Remarks

The association between nymph and imago stages of this new species was confirmed through indoor rearing and COI sequence comparison.

The penis lobes of S. lacustris and S. polyspineus sp. nov. are highly similar but exhibit subtle differences. In S. polyspineus sp. nov., dorsal elongation of penis lobe is short and blunt, inner margin of penis lobe has approximately 12 small spines and outer margin has about 7 serrated small spines. The posterolateral projection of penis lobe is slender and sharply pointed ( Figs 24G–J View FIGURE 24 ). In contrast, dorsal elongation of penis lobe in S. lacustris is short and sharply pointed, inner margin of penis lobe has 5–6 long spines and outer margin has about four small spines. The posterolateral projection of penis lobe is short and broad ( Figs 10H–J View FIGURE 10 ).

In addition, inner margin of penis lobe in S. polyspineus sp. nov. bears numerous small spines, similar to those of S. abraxas Jacob, 1986 S. columbianus McDunnough, 1925 , S. barbaroides McDunnough, 1929 , and S. occidentalis Eaton, 1885 . However, posterolateral projection of penis lobe of this species is more distinctly slender and sharply pointed, and posterior margin of penis lobe lacks any indentation ( Fig. 24J View FIGURE 24 ).

Navás (1912) originally described a species Andromina grisea from Far-East Russia. Edmunds (1960) later transferred this species to the genus Siphlonurus , a combination subsequently confirmed by Kluge (2004). This species was based on two female subimaginal specimens. Given the distribution and type locality of Siphlonurus griseus , it is possible that our newly described species, S. polyspineus sp. nov., could be the additional finding of S. griseus . However, this hypothesis requires further verification, including additional collections from the type locality and molecular confirmation via COI sequence analysis. At present, we consider the designation of a new species ( S. polyspineus sp. nov.) to be the best arrangement.