Paegniodes sapanensis Boonsoong, Sartori & Auychinda, 2021

Boonsoong, Boonsatien, Auychinda, Chonlakran, Sartori, Michel & Khanyom, Nuttakun, 2021, First record of Paegniodes Eaton, 1881 (Ephemeroptera, Heptageniidae) from Thailand with description of a new species, ZooKeys 1036, pp. 153-170 : 153

publication ID	https://dx.doi.org/10.3897/zookeys.1036.64880
publication LSID	lsid:zoobank.org:pub:9A2C63EC-D583-418F-8277-3DAEC567EED6
persistent identifier	https://treatment.plazi.org/id/1C749EC4-356B-4CCD-A22F-9C3AADD603AA
taxon LSID	lsid:zoobank.org:act:1C749EC4-356B-4CCD-A22F-9C3AADD603AA
treatment provided by	ZooKeys by Pensoft
scientific name	Paegniodes sapanensis Boonsoong, Sartori & Auychinda
status	sp. nov.

Treatment

Paegniodes sapanensis Boonsoong, Sartori & Auychinda sp. nov. Figures 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10

Materials examined.

Holotype. 1 female mature larva in alcohol, deposited in ZMKU, Thailand, Nan province, Bo Kluea district, Sapan waterfall , 19°11'25.8"N, 101°11'56.3"E, 800 m, 21.III.2020, B. Boonsoong leg. GoogleMaps

Paratypes. 3 larvae in ethanol, deposited in ZMKU, same data as holotype GoogleMaps ; 2 larvae in ethanol, GBIFCH00834844 , deposited in MZL same locality as holotype, 26.XI.2019, B. Boonsoong leg. GoogleMaps ; 1 male subimago (reared from larva), 2 female subimagos (reared from larvae), 2 larvae, all in ethanol, deposited in ZMKU, same locality as holotype, 29.XI.2020, B. Boonsoong leg. GoogleMaps

Description of larva.

Body length 16.2 mm (holotype) 10.0-13.5 mm (exuvia) 7.2-11.5 mm (immature), caudal filaments ca 1.5 × of body length (immature).

General colouration dark brown with pale markings on tibiae and abdominal tergites.

Colouration (Figs 1 View Figure 1 , 10A-C View Figure 10 ). Head, thorax, legs, and abdomen dorsally dark brown. Head, thorax, legs, and abdomen ventrally whitish. Caudal filaments brown.

Head. Head capsule. Ovoid in shape and flattened, 1.8-2.5 mm in length, 2.5-4.1 mm in width, brown, without distinct markings (Fig. 2A View Figure 2 ); head capsule margins smooth. Compound eyes and base of ocelli black.

Antenna (Figs 2A View Figure 2 , 10A View Figure 10 ). Antennae length slightly longer than head width, scape and pedicel dark brown, flagellum light brown.

Labrum (Fig. 2B View Figure 2 ). Triangular, width of labrum 1/3 of head capsule, with median notch on anterior margin, anterior margin with row of long, hair-like setae; dorsal surface with hair-like setae except at notch and nearby area.

Left mandible (Fig. 2C View Figure 2 ). Outer and inner incisors acute with serrated margins, row of bristles located near inner incisor, row of fine serrated spines locate on base of outer and inner incisors, margin between inner incisor and mola slightly concave and smooth, one distinct denticle ventrally near mola area, setae present at apex of mola (Fig. 2D View Figure 2 ). Lateral margin without row of setae.

Right mandible (Fig. 2E View Figure 2 ). Outer and inner incisors acute with serrated margins, row of bristles located near inner incisor, row of fine serrated spines locate on base of outer and inner incisors, margin between inner incisor and mola slightly concave, tuft of setae locate on inner margin near mola, setae present at apex of mola (Fig. 2F View Figure 2 ). Lateral margin without row of setae.

Hypopharynx (Fig. 3A View Figure 3 ). Lingua subequal to superlingua, longer than broad, with medial tuft of long, stout setae. Superlingua distally almost straight, nearly square; each superlingua with notch on anterior margin, lateral margin rounded, with fine, long, simple setae along laterodistal margin.

Maxilla (Fig. 3B View Figure 3 ). Crown of galea-lacinia with a row of eight comb-shaped setae, apex of maxilla with three canines; two dentisetae, and one row of long setae on inner margin, with a row of submarginal setae on ventral surface; maxillary palpi two-segmented, apical one 1.6 × length of basal segment; ventral surface of segment II with row of dense setae forming brush-like structure, apex of last segment apically lanceolate.

Labium (Fig. 3C View Figure 3 ). Labium with U-shaped separation between glossae; shape of glossae conical, inner margin covered with dense setae, outer margin with row of setae; paraglossae moderately expanded laterally, with dense apical setae; basal segment of palp slightly longer than length of apical segment; apical segment slightly pentagonal, apex with broad projection (Fig. 3D View Figure 3 ); with dorsal transverse row of setae apically and setae brush ventrally.

Thorax. Foreleg (Fig. 4A View Figure 4 ) Coxa with well-developed, round dorsal plate; tibia subequal to femur in length, tarsus about ¼ length of tibia; femur with regular row of bristles on outer margin and many scattered, mostly spatulate setae on dorsal surface, ventrally with whitish elongated oval area (Fig. 4B View Figure 4 ); tibia and apex of tarsus pigmented in light yellow; tarsus brown to dark; claw with a submedian denticle and three apical denticles (Fig. 4C View Figure 4 ). Middle and hind legs as foreleg but with patellar-tibial (fusion) sutures, apex of tibia with cluster of setae on inner surface, and claw with two or three apical denticles. Mesosternum with a distinct transverse yellow macula (Fig. 4D View Figure 4 ).

Abdomen. Terga (Fig. 6A View Figure 6 ). Terga pale brown, each tergum with two submedian pairs of pale dots; mature larva with distinct brown median stripes on terga II-VII, with brown oblique stripes on lateral margin of terga III-VII, posterior margin of each tergum with row of strong and acute denticles, posterolateral projections extended into acute projections.

Gills (Fig. 5 View Figure 5 ). Gills on abdominal segments I-VII; gill I (Fig. 5A View Figure 5 ) smaller than others, dorsal lamellae 1/4 in length of well-developed fibrilliform portion; gill II-VII similar in shape (Fig. 5B-G View Figure 5 ), lamellae much longer than fibrilliform portion, tracheation clearly visible, proximal half of lamellae margin thickened and sclerotised, gill IV (Fig. 5D View Figure 5 ) relatively larger than others.

Caudal filaments (Fig. 6B View Figure 6 ). Cerci subequal to paracercus in length, paracercus laterally with long setae on both margins of each segment, similar setae located on inner margins of cerci only.

Diagnostic characters of larval stage.

The main diagnostic characters are: i) lamellae of gill I ca 1/4 of fibrilliform portion, ii) mandibles without dense hair-like setae on lateral margin, iii) basal segment of maxillary palp without hairlike setae on margins, and iv) apical segment of labial palp slightly pentagonal with broad projection at apex.

Description of adult stages.

Male subimago (in ethanol Fig. 7 View Figure 7 , living Fig. 10E View Figure 10 )

Body length 8.5 mm, cerci 17.5 mm, forewing 10.9 mm, hindwing 1.5 mm.

Colouration (Fig. 7 View Figure 7 ). Head, thorax and abdomen dorsally yellowish brown. Head, thorax, and abdomen ventrally light yellow. Legs yellow. Caudal filaments brownish.

Head (Fig. 7A View Figure 7 ). Compound eyes separated by 3.0 × width of median ocellus. Thorax (Fig. 7A, D View Figure 7 ). Pronotum and mesonotum each with pair of dark dots; forewings semitransparent, veins yellowish to brown (Fig. 7B View Figure 7 ); hindwings 0.14 size of forewings (Fig. 7C View Figure 7 ). Legs yellowish to yellowish brown; femora brown with proximal and distal light maculae; tibiae uniformly brown; tibiae slightly shorter than femora. Forelegs (Fig. 7E View Figure 7 ): length of leg segments: femur 2.5 mm; tibia 2.3 mm; tarsus 2.0 mm (tarsal segments in order of decreasing length: 2>3>4>1>5). Midlegs: (Fig. 7F View Figure 7 ) length of leg segments: femur 2.4 mm; tibia 2.1 mm; tarsus 1.2 mm (tarsal segments in order of decreasing length 2>1>5>3>4). Hindlegs (Fig. 7G View Figure 7 ): length of leg segments: femur 2.8 mm; tibia 2.2 mm; tarsus 1.2 mm (tarsal segments in order of decreasing length: 1≥5>2≥3>4). Each leg with two claws; one blunt, and one sharp and hooked.

Abdomen. Dorsally with ornamentation as in Fig. 7H View Figure 7 , tergum I with transverse dark band, terga II-VII with distinct, reddish median band; laterally with pattern as in Fig. 7I View Figure 7 , with clearly oblique stripes on terga III-VII but those on terga II and VIII less visible; all sterna predominantly light yellow (Fig. 7J View Figure 7 ). Combined length of two terminal segments of gonopods half the length of basal one (Fig. 7K, L View Figure 7 ). Penis lobes jointed at base, apices separated, each penis lobe apex slightly expanded laterally. Styliger plate with concave posterior margin, but median part convex (Fig. 7L View Figure 7 ). Cerci reddish to brown.

Female subimago (in ethanol Fig. 8 View Figure 8 , living Fig. 10D, F View Figure 10 )

Body length 12.8 mm, cerci 20.0 mm, forewing 14.4 mm, hindwing 2.6 mm.

Colouration (Fig. 8 View Figure 8 ). Head, thorax and abdomen dorsally brown. Head, thorax and abdomen ventrally light brown. Legs yellow. Caudal filaments brown.

Head (Fig. 8A View Figure 8 ). Compound eyes separated by 3.0 × width of median ocellus.

Thorax (Fig. 8A, D View Figure 8 ). Pronotum and mesonotum each with pair of dark dots, sternum light brown; forewings semitransparent, veins yellowish to brown (Fig. 8B View Figure 8 ); hindwings 0.18 the size of the forewings (Fig. 8C View Figure 8 ). Legs yellowish to yellowish brown; femora brown with proximal and distal light maculae; tibiae uniformly brown; foretibiae equal to femora; tibiae of midleg and hindleg slightly shorter than femora. Forelegs (Fig. 8E View Figure 8 ): length of leg segments: femur 3.1 mm; tibia 3.1 mm; tarsus 1.7 mm (tarsal segments in order of decreasing length: 2>3>5>1>4). Midlegs (Fig. 8F View Figure 8 ): length of leg segments: femur 2.9 mm; tibia 2.7 mm; tarsus 1.4 mm (tarsal segments in order of decreasing length 2>1≥3≥5>4). Hind leg (Fig. 8G View Figure 8 ): length of leg segments: femur 3.5 mm; tibia 3.0 mm; tarsus 1.2 mm (tarsal segments in order of decreasing length: 5>1≥2>3>4). Each leg with two claws; one blunt, and one sharp and hooked.

Abdomen. Dorsally with ornamentation as in Fig. 8H View Figure 8 , tergum I with dark band, with distinct reddish median band on terga II-VII; laterally with pattern as in Fig. 8I View Figure 8 , with clearly oblique stripes on terga III-VII but those on terga II and VIII less visible; all sterna predominantly light yellow (Fig. 8J View Figure 8 ); subgenital plate (sternum VII) distally rounded and subanal plate (sternum IX) extended, with shallow median notch (Fig. 8K View Figure 8 ); cerci reddish brown, with tiny setae on surface.

Description of egg.

(dissected from female subimago). Length ca 155-175 µm, width ca 80-95 µm; elongate and oval in shape (Fig. 9A, B View Figure 9 ); chorionic surface covered with hexagonal and pentagonal mesh ridges, with 1-4 knob-terminated coiled threads (KCTs) in between (Fig. 9C View Figure 9 ); tagenoform micropyle in equatorial area (2 or 3 micropyles clearly visible on the same side) (Fig. 9D View Figure 9 ).

Diagnostic characters of imaginal stage.

The diagnostic characters to distinguish our new species from P. cupulatus are: i) the median stripes on abdominal terga and ii) lateral margins of genital plates slightly concave near apex.

Etymology.

The specific epithet is named for the Sapan waterfall (Bo Kluea district; tourist attraction of Nan province, Thailand), where the holotype is known.

Distribution.

Nan province.

Biological aspects.

The specimens were collected from tropical mountain streams (Fig. 11A View Figure 11 ) which are slightly disturbed by tourist activities. The larvae of the new species were found in flowing areas and the littoral zone of the streams, underneath a mostly cobble substrate (Fig. 11B, C View Figure 11 ).

Molecular analysis.

Two COI sequences of Paegniodes were retrieved from BOLD system and GenBank (Table 1 View Table 1 ). One sequence from BOLD (THMAY162-12) was based on a specimen from the same locality (Namtok Sa Pan) as this study and this specimen was identified as P. dao . However, our Kimura 2-parameter (K2P) analysis revealed that intraspecific genetic divergence of the three sequences is very low (0.03%), and we considered all sequences as belonging to the same species. In addition, the interspecific distances (COI) between the new species and Paegniodes cupulatus ranged from 11.43-11.73%.