Tenuibaetis panhai, Suttinun & Gattolliat & Boonsoong, 2022

Suttinun, Chanaporn, Gattolliat, Jean-Luc & Boonsoong, Boonsatien, 2022, First report of the genus Tenuibaetis (Ephemeroptera, Baetidae) from Thailand revealing a complex of cryptic species, ZooKeys 1084, pp. 165-182 : 165

publication ID	https://dx.doi.org/10.3897/zookeys.1084.78405
publication LSID	lsid:zoobank.org:pub:1F7A3F8B-31D9-481D-B7EC-4357CADC4D2D
persistent identifier	https://treatment.plazi.org/id/B39C17B1-A135-4DEC-8172-CB6C497F89AD
taxon LSID	lsid:zoobank.org:act:B39C17B1-A135-4DEC-8172-CB6C497F89AD
treatment provided by	ZooKeys by Pensoft
scientific name	Tenuibaetis panhai
status	sp. nov.

Treatment

Tenuibaetis panhai sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Type material.

Holotype. Thailand • larva; Kanchanaburi, Thong Pha Phumi District, Pra Chum Mai; 14°34'58"N, 98°34'52"E; 269 m; 31 Jan. 2019; leg. C. Suttinun; on slide; Genbank OM264189; TEKN01; ZMKU. Paratypes. Thailand • 7 larvae; same data as holotype; 1 on slide TEKN03; 4 in alcohol; ZMKU; 1 on slide GBIFCH00829251; 1 in alcohol; TEKN02; GBIFCH00673241; MZL. Other material. Thailand • 1 larva; Kanchanaburi, Thong Pha Phumi District, Pat Sadu Klang; 14°33'11"N, 98°33'94"E; 349 m; 1 Feb. 2019; leg. C. Suttinun; in alcohol; ZMKU. • 6 larvae; Kanchanaburi, Thong Pha Phumi District, Huai Pak Kok; 14°39'57"N, 98°32'04"E; 175 m; 1 Feb. 2019; leg. C. Suttinun; in alcohol; ZMKU. • 2 larvae; Kanchanaburi, Thong Pha Phumi District, Huai Pheung Ban Lung Yee; 14°58'21"N, 98°53'50"E; 709 m; 1 Feb. 2018; leg. C. Auychinda; 1 in alcohol (mouthpart); Genbank OM319584; TEKN05; TEKN06; ZMKU. • 1 larva; Ratchaburi, Suan Phueng District, Bo Klueng; 13°31'46"N, 99°14'66"E; 180 m; 25 Nov. 2018; leg. C. Suttinun; in alcohol (mouthpart); Genbank OM302269; TERB01; ZMKU. • 5 larvae; Petchaburi, Kaeng Krachan District, Huai Sat Lek; 12°38'15"N, 99°30'60"E; 166 m; 25 Feb. 2018; leg. C. Suttinun; 4 in alcohol; 1 on slide; Genbank OM302305, OM319569; TEPC02; ZMKU. • 14 larvae; Loei, Phu Luang District, Ban Non Pattana; 17°06'41"N, 101°28'72"E; 527 m; 18 Dec. 2018; leg. C. Suttinun; 10 in alcohol; 3 on slides; Genbank OM302308, OM303507; TELE01; TELE03; TELE04; ZMKU; 1 on slide; TELE02; GBIFCH00829259; MZL • 2 larvae; Chiang Rai, Mueng District, Mae Korn Stream; 19°51'77"N, 99°39'08"E; 534 m; 6 May. 2019; leg. C. Suttinun; in alcohol; ZMKU. • 2 larvae; Chiang Rai, Mueng District, Nang Lae Nai waterfall; 20°03'16"N, 99°49'28"E; 529 m; 7 May. 2019; leg. C. Suttinun; 1 in alcohol; 1 on slide; Genbank OM303508; TECR02; ZMKU. • 3 larvae; Chiang Rai, Mae Chan District, Huai Kang Pla waterfall; 20°05'36"N, 99°46'80"E; 519 m; 7 May. 2019; leg. C. Suttinun; 2 in alcohol; 1 on slide; Genbank OM302358; TECR01; ZMKU.

Description.

Coloration (Fig. 1 View Figure 1 ). Head dorsally brown and yellow, with a yellow marking between ocelli. Thorax dorsally brown, pronotum with (Fig. 1C View Figure 1 ) or without (Fig. 1A View Figure 1 ) posterior yellow marking; mesonotum medially with a yellow transverse band. Abdomen dorsally brown; tergite III with (Fig. 1A View Figure 1 ) or without (Fig. 1C View Figure 1 ) a pair of yellow markings on lateral sides; tergite IV yellowish with or without median brown marking; tergite V with or without anterior yellow marking; tergite VIII with or without posterior yellow marking; tergites IX-X yellow. Head and thorax ventrally whitish; abdomen ventrally light brown; sternites VI-VIII darker brown; sternites IX-X yellow. Legs light brown; dorsal, ventral, and apical femur margins darker brown with brown stripes distomedially; claws distally dark brown. Caudal filaments light brown without darker band or pattern.

Head. Antenna. Flagellum with lanceolate spines at apex of each segment.

Labrum (Fig. 2A View Figure 2 ). Subrounded, length 0.66-0.74 × maximum width. Distal margin with medial emargination. Dorsally with submarginal arc composed of one long, pointed, simple seta medially plus two long, pointed, simple setae laterally and four long, pointed, simple setae decreasing in size along margin; dorsal surface with short, fine, simple setae scattered medially toward the basal area. Ventrally with submarginal row of setae composed of about 20 lateral long, feathery setae equal in size and a row of stout, simple setae laterally near margin.

Right mandible (Fig. 2B, C View Figure 2 ). Incisors fused. Outer set with 4 denticles composed of two pointed denticles plus one larger, blunt denticle and one pointed denticle; inner sets with 4 pointed denticles; each denticle separated by a deep groove. Inner margin of innermost denticle with a row of minute teeth. Prostheca robust, apicolaterally denticulate. Margin between prostheca and mola straight, without setae. Tuft of setae at apex of mola present.

Left mandible (Fig. 2D, E View Figure 2 ). Incisors fused. Outer and inner sets of pointed denticles with 3 + 3 denticles; each denticle separated by a deep groove, plus a minute intermediate denticle between sets. Inner margin of innermost denticle with minute denticles. Prostheca slightly shorter than incisor, robust, apically denticulate, with a comb-shaped structure. Margin between prostheca and mola straight without setae. Tuft of spine-like setae absent at base of mola. Subtriangular process long and wide, above level of area between prostheca and mola. Denticles of mola apically as wide as basal. Setae present at apex of mola.

Both mandibles with lateral margin almost straight. Basal half with fine, simple setae scattered over dorsal surface.

Hypopharynx (Fig. 2F View Figure 2 ). Lingua slightly shorter than superlingua, longer than broad, with medial tuft of long, thin setae. Superlingua distally with a concave margin, with long, fine setae along distal margin; lateral margin rounded with simple setae along lateral margin.

Maxilla (Fig. 2G View Figure 2 ). Galea-lacinia with two long, fine, simple setae under crown. Inner dorsal row of setae with three denti-setae; distal denti-seta tooth-like, middle denti-seta slender and pectinate, proximal denti-seta very long, slender, simple setae. Medially with one trifid, stout seta and five short to long, simple setae. Maxillary palp 1.4-1.5 × as long as length of galea-lacinia, 2-segmented; fine, simple setae scattered over surface of maxillary palp. Palp segment II 1.3 × length of segment I. Apex of last segment conical.

Labium (Fig. 2H View Figure 2 ). Glossae basally broad, narrowing toward apex, shorter than paraglossae; inner margin with nine long, simple setae; apex with one long, simple seta and two medium, robust, pectinate setae; outer margin with four long, simple setae; dorsal surface with a long, simple seta medially; basal area with fine scattered setae. Paraglossae sub-rectangular, apically rounded, with three rows of setae, distal row of very long, pectinate, simple setae, other rows of pectinate long and medium setae; one curved, blunt, simple seta at inner apical margin; two long, simple setae in outer margin near three rows of setae; dorsal surface with one medium, simple seta anteromedially; dorsally with row of five long, simple setae parallel to inner margin, with an arc of three long, simple setae at outer margin; basal area with medium, spine-like setae scattered. Labial palp with segment I 0.8 × length of segments II and III combined. Segment I covered with micropores and few fine, simple setae. Segment II with poorly developed, apically rounded, distomedial protuberance; tuft of medium, fine, simple setae present at apex of protuberance; inner margin with medium, fine, simple setae; outer margin with short, fine, simple setae; dorsally with medium, fine, simple, scattered setae; dorsally with row of 4-6 medium, simple setae. Segment III conical, slightly asymmetrical; length subequal to width; covered with medium simple setae and stout simple setae anterolaterally.

Thorax. Hindwing pads (Fig. 3A View Figure 3 ). Absent.

Foreleg (Fig. 3B-D View Figure 3 ). Ratio of foreleg segments 2.1:1.5:1:0.4. Femur. Length 2.9 × maximum width; dorsal margin with a row of 18-25 apically rounded, simple setae; length of setae 0.2 × maximum width of femur; anterior surface with 5-10 spatulate setae medially and about 28 acute, lanceolate setae close to ventral margin; apex rounded, with one pair of apically rounded, simple seta and two rows of stout, apically rounded, simple setae along apical margin; posterior surface with one row of stout, spatulate setae transverse anteromedially; femoral patch strongly developed. Tibia. Dorsal margin with a few short, spine-like setae and a pair of short, spine-like seta apically; ventral margin with a row of 7-13 acute, spine-like, curved setae and three long, spine-like apical setae; tibio-patella suture on basal 2/3 area with a row of eight stout, spatulate setae along suture. Tarsus (Fig. 3B, C View Figure 3 ). Dorsal margin nearly bare, with a few acute, simple setae on proximal area; ventral margin with one row of acute, curved, spine-like setae increasing apically; apex with one short, spine-like seta; claw curved, apically pointed, with one row of 11-13 denticles increasing apically; subapical setae absent.

Abdomen. Terga (Fig. 3H View Figure 3 ). Surface with scattered scales or scale-bases and micropores. Posterior margin of terga with row of apically, blunt, triangular spines.

Gills (Fig. 3E-G View Figure 3 ). Present on segments I-VII; oval shaped. Margins serrate with small spines. Tracheation (Fig. 3F View Figure 3 ) extending from main trunk to inner and outer margins. Gill I (Fig. 3E View Figure 3 ) reduced, 0.3 × length of segment II; gills II-VI 1.2 × length of following segment; gill VII (Fig. 3G View Figure 3 ) 0.8 × length of segment VIII.

Paraproct (Fig. 3I, J View Figure 3 ). Posterior margin with 5-7 pointed spines; surface with U-shaped scale base, micropores and fine, simple setae, and with a patch of notched scales (Fig. 3J View Figure 3 ); posterolateral extension (cercotractor) with 9-12 marginal spines.

Caudal filaments (Fig. 1 View Figure 1 ). Cerci ca. 0.5 × body length. Paracercus ca. 0.4 × body length.

Diagnostic characters.

Larva. The main diagnosis character is the absence of hindwing pads, followed by a combination of characters: A) distinct pattern on thorax and abdomen or "Zebra form," as in Fig. 1 View Figure 1 ; B) labrum dorsal submarginal arc composed of one long, pointed, simple seta medially plus two long, pointed, simple setae laterally and four long, pointed, simple setae decreasing in size along margin; C) right mandible: incisors with 4 + 4 pointed denticles, each denticle separated by a deep groove; D) left mandible: incisors with 3 + 3 pointed denticles plus a minute intermediate denticle between sets; E) hypopharynx: lingua with medial tuft of long, fine setae; superlingua lateral margin with long, simple setae; F) maxillary palp longer than galea-lacinia, apex conical; G) femur: dorsal margin with 15-25 apical rounded, simple seta, anterior surface with 5-10 spatulate setae; H) claw with a row of 11-13 denticles; I) paraproct: distal margin with 5-7 spines, surface with a patch of notched scales.

Winged stages.

Unknown.

Etymology.

Tenuibaetis panhai sp. nov. is dedicated to Professor Dr. Somsak Panha (Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand) for his outstanding contributions to the systematics study of the fauna in Thailand.

Distribution.

Kanchanaburi (KN), Ratchaburi (RB), Petchaburi (PC), Chiang Rai (CR), and Loei (LE) provinces of Thailand.

Biological aspects.

The specimens were collected in headwater streams (Fig. 4A View Figure 4 ) and above waterfalls at different altitudes (150-700 m a.s.l.). The streams were mostly located in forest areas with a partly complete canopy; the substrate was dominated by pebbles, gravel, and sand. The larvae were found on the undersides of pebbles in fast-flowing water (Fig. 4B View Figure 4 ). The waterfalls were located in areas with human disturbing activity as tourist attractions. They were collected together with other mayfly species: Cymbalcloeon sartorii Suttinun, Gattolliat & Boonsatien, 2020 ( Baetidae ), Liebebiella vera ( Baetidae ), and Afronurus spp. ( Heptageniidae ).

Molecular analysis.

COI sequences were obtained from specimens for each locality (Table 2 View Table 2 ). The K2P analysis revealed interspecific distances between T. panhai sp. nov. and the available Tenuibaetis species ranging between 17% and 27% (Table 3 View Table 3 ). The intraspecific distance was very limited within the nine sequences of T. panhai sp. nov. (0% to 4%).

Sequences of eight specimens, morphologically indistinct from T. panhai sp. nov. present genetic distance ranging between 15% and 20% to T. panhai sp. nov. These eight sequences are separated into two distinct groups. To depict the genetic diversity of Tenuibaetis in Thailand, we propose to consider these two groups as Molecular Operational Taxonomic Units (MOTUs) corresponding respectively to T. cf. panhai sp. I (Southern) and T. cf. panhai sp. II (Chiang Dao), based on genetic evidence only (COI; Table 2 View Table 2 ). The K2P distances of T. cf. panhai sp. I and T. cf. panhai sp. II range between 22% and 24% (Table 3 View Table 3 ). The intraspecific distances within MOTUs are limited (0% to 3%).

The COI reconstruction was built by the Bayesian Interference (BI) using MrBayes (Fig. 5 View Figure 5 ). Seventeen sequences of Tenuibaetis in Thailand are separated into two main distinct clades: the first clade includes T. panhai sp.nov. and T. cf. panhai sp. I while the second clade includes T. cf. panhai sp. II and T. frequentus .