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Detalles Bibliográficos
Main Authors:	Kluge, Nikita J., Vishnevskaya, Maria S.
Formato:	Recurso digital
Idioma:
Publicado:	Zenodo 2026
Subjects:	Biodiversity Taxonomy Animalia Arthropoda Insecta Ephemeroptera Baetidae Labiobaetis Labiobaetis ludmilae
Acceso en liña:	https://doi.org/10.5281/zenodo.19174384
Tags:	Engadir etiqueta Sen Etiquetas, Sexa o primeiro en etiquetar este rexistro!

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Labiobaetis ludmilae sp. nov.(Figs 1–39, 41–78)Labiobaetis sp. 12: Suttinun 2020 (MS): 142, figs 32G–H (larva).Material examined. Holotype: L-S-I &male; {number [IX] (4) 2025}, LAOS, river Mekong near lower end of island Don Det, 13°57′42″N, 105°54′55″E, 7.II.2025, coll. N. Kluge & L. Sheyko. Paratypes: the same place and collectors, 6–10.II.2025: 1 L-S-I &male;, 1 L-S-I &female;, 15 larvae; 23–28.I.2024: 1 L-S &male;, 1 S-I &male;, 1 L-S-I &female;, 6 larvae. THAILAND: Nakhon-Nayok prov., river Nakhon-Nayok upstream Nakhon-Nayok just below dam, 19–21.II.2025, coll. Kluge & Sheyko: 2 L-S-I &male;, 3 L-S-I &female;, 1 L-S &female;, 40 larvae; Kanchanaburi prov., Lad-Ya, river Kwai-Yai near mouth of river Taphoen, 27–31.I.2015, coll. N. Kluge & L. Sheyko: 1 immature larva.Larva. CUTICULAR COLORATION (Figs 6–18). Head varying from nearly entirely brown (Fig. 11) to brown in anterior part and colorless in posterior part (Fig. 17). Cervical sclerites brown (Fig. 10).Pronotum and mesonotum varying from mostly brown with colorless blanks (Figs 6–13) to mostly colorless with brown maculae (Figs 15–18). Propleura and mesopleura varying from brown (Fig. 10) to colorless. Metanotum and metapleura brown with lighter or colorless areas (Fig. 10). Thoracic sterna and abdominal sternum I colorless. Cuticular pigmentation of legs most extensive on fore leg, less extensive on hind leg (Figs 8–10). Femora partly colorless, with apex brown, with or without wide brown band or spot at midlength (Fig. 5). Tibia varying from mostly brown with patella-tibial suture colorless (Figs 5, 8) to mostly colorless with brown macula on inner side of patella (Fig.10).Abdominal tergum I either mostly brown (Fig. 7), or brown anteriorly and colorless posteriorly; terga II–VII with paired colorless medio-anterior and medio-posterior sigilla on brown background; tergum IV either as dark as neighboring ones (Fig. 7), or with colorless transverse blank near posterior margin (Figs 12, 14, 16); terga VII and X lighter than others, either brown only in anterior part and colorless in posterior part (Fig. 7), or entirely colorless (Fig. 16). Abdominal sterna I–VII mostly colorless; either with more or less large brownish areas (Fig. 7), or with unpaired brownish macula near anterior margin only; sterna VIII– IX mostly brownish. Caudalii brownish near base, colorless in proximal part, contrastingly dark brown in middle part, colorless in distal part; apical, slender, setae-less area of cercus brownish (Figs. 7, 41–42).COLOR VARIABILITY. Individuals from Nakhon Nayok darker, with more extensive brown cuticular pigmentation (Figs 3–4, 6–12); individuals from river Mekong (with warmer water) lighter, with less extensive pigmentation (Figs 1–2, 13–18), often with entirely colorless abdominal terga VII and X.HYPODERMAL COLORATION. Not expressed. In some larvae ready to molt to subimago, characteristic hypodermal coloration of abdomen (Fig. 61) visible through larval cuticle.SHAPE AND SETATION. General body shape characteristic for strong swimmers (Figs 1–4), i.e. similar to that of Baetis rhodani (Pictet 1843).Frons between bases of antennae not wide, flat, with shallow longitudinal concavity (Fig. 22). Frontal suture in both sexes acute-angled (Fig. 22). Scape with well-developed lateral-apical projection (Fig. 22). Labrum with pair of submarginal rows of setae arched, composed of feathered setae (Figs 23–34). Mandibles with incisor and kinetodontium fused, margin between prostheca and mola slightly convex, small setal tuft on medio-proximal corner of mola present (Figs 25–28). Apical setae on hypopharynx not longer that others, not forming distinct tuft (Fig. 34). Maxilla with 2 small setae laterad of canines; 1st (distal) dentiseta stout and bent at same direction as canines; 2nd and 3rd dentisetae bifurcate (Fig. 30). Maxillary palp with excavation on inner side of 2nd (terminal) segment (Fig. 29). Labium (Figs 31, 32, 33): Glossa narrowed in proximal part, widest near midlength; median setal row containing 9–10 spine-like setae, distalmost seta slightly longer than others; apex with 2–3 long, stout setae; dorso-lateral row located on lateral margin and containing 4–7 setae; ventral row containing 6–8 setae and some irregularly located setae near base. Paraglossa with long apical setae forming 3 regular rows on its ventral side; ventro-median row located far from median margin and containing 3–5 setae; dorso-median row adjacent to median margin and containing 3–5 setae. Disto-median projection of 2nd segment of labial palp long and wide (appearing narrower on entire palp— Fig. 31 and wider on compressed empty exuviae— Figs 32–33).Hind protoptera or their vestiges absent (Fig. 10).Legs of all pairs with equal femur length; fore femur slightly wider than others in proximal part; tibia and tarsus longest on fore leg, shortest on hind leg (Figs 8–10). Femoral patch (‘villopore’) completely absent on all legs. Patella-tibial suture terminated near midlength of tibia on all legs (Fig. 5). Setation equal on all leg pairs. Femora, tibiae and tarsi densely covered with small scales in semicircular sockets (Figs 5, 35–37). Small, blunt, colorless, 2-channel setae projected perpendicular to surface, densely situated on apical side of femur (Fig. 35), outer side of tibia (Fig. 36) and outer side of tarsus (Fig. 37). Inner side of femur with very short, blunt, 2-channel setae (Fig. 5). Inner side of tibia with longer 2-channel setae (Fig. 36). Inner side of tarsus with even longer 2-channel setae (Fig. 37). Claw moderately hooked, with row of 12–15 denticles gradually increasing from most proximal to most distal ones (Fig. 37).Abdominal segments II–IX with equally developed, pointed, sclerotized posterolateral spines (Figs 19–20). Surface of abdominal terga and sterna densely covered with scales in wide semicircular sockets (Fig. 39). Denticles on posterior margin of tergum I very small, short and blunt (Figs 44–45). Denticles on posterior margins of terga II–V differentiated: on median part of tergum denticles shorter, directed caudally, blunt or pointed; laterad of them, denticles longer, sharply pointed and directed caudally-laterally (Figs 39, 46–49). Denticles on terga VI–VIII all sharply pointed, less differentiated or non-differentiated and directed caudally (Figs 50–52); on tergum IX middle part of hind margin behind pair of submedian setae with smaller denticles (Fig. 53). Denticles on tergum X sharply pointed, all directed caudally (Fig. 53). Posterior margins of abdominal sterna I–V without denticles. Denticles on posterior margins of sterna VI–IX pointed as equilateral triangles (Fig. 38); in male, denticles of sternum IX narrower and located between protogonostyli (Fig. 43). Paraprocts not stretched caudally, with large, pointed denticles increasing posteriorly (Fig. 38).All 7 pairs of tergalii present. Tergalius I about as large as tergalii II–VI, with marginal ribs expressed in proximal part only, without marginal denticles (Fig. 19). Tergalii II–VII with costal and anal marginal ribs; their distal parts with setae-bearing denticles (Figs 19–21).Paracercus fully developed, with long, dense swimming setae up to end (Fig. 42). Cercus with portion bearing swimming setae slightly longer than paracercus (Fig. 41); terminal, slender, setae-less portion of cercus nearly as long as portion bearing swimming setae (Fig. 7).POSE OF SUBIMAGINAL GONOSTYLI DEVELOPING UNDER LARVAL CUTICLE (Figs 72–73). Gonostyli folding « Acentrella - type » (according to Kluge & Novikova 2011: 12, fig. 25): 2nd and 3rd segments directed medially with most caudal point located at their joining (Fig. 72).Subimago. CUTICULAR COLORATION. Head and thorax with contrasting brown and colorless areas (Figs 55–57). Mesonotum mostly brown, with contrasting colorless medioparapsidal sutures (Fig. 54). Legs with brown and colorless areas (Fig. 57); apex of each tarsal segment bordered with contrasting brown (Fig. 58). Abdominal terga and sterna light brown, with small colorless sigilla; sterna slightly lighter (Fig. 62). Cerci colorless with contrasting brown setae and their bases (Fig. 59).HYPODERMAL COLORATION. As in imago (Fig. 61).TEXTURE. On all legs of both sexes, terminal segment covered with pointed microlepides; other segments covered mostly with blunt microlepides, with pointed microlepides at apex (Fig. 58).Imago, male (Figs 63–66). Head ochre. Turbinate eyes dark red, with wide facetted surface. Thorax with ochre and brown areas. Fore wings colorless, with veins ochre; pterostigma with several simple, oblique, incomplete and complete veins. Hind wings absent. Legs of all pairs ochre with diffusive macula on distal part of femur and diffusively brown proximal part of tibia (Fig. 67). Tarsus of middle and hind legs with 2 apical spines (on initial 2nd and 3rd tarsomeres) (Fig. 67; as in Fig. 58). Abdominal terga with ochre and brown areas of characteristic shape; terga V–VI and IX with extensive lighter ochre or whitish areas. Abdominal sterna ochre; sterna II–VII with pair of contrasting, brown, longitudinal stripes near lateral margins; sternum VIII with pair of more extensive brown maculae; sternum IX entirely light ochre. Cerci uniformly dark brown.Male genitalia (Figs 69–71). Distal margin between unistyligers (penial bridge) shallowly convex, poorly sclerotized. 1st segment of gonostylus cylindrical, gradually narrowing distally; 2nd segment sharply widened distally, with prominent inner-distal projection; 3rd (apical) segment elongate, widened apically. Gonovectes sharply bent. Sterno-styligeral muscle completely absent.Imago, female (Fig. 68). Coloration similar to that of male.Egg. Irregularly spherical, with crumpled layers of chorion, without regular relief (Figs 74–78).Dimension. Fore wing length (and approximated body length) 5–6 mm.Distribution. Indochina: known from Thailand and Laos.Collecting sites. Larvae were found in a few places with fast current and stony bottom (Figs 79–80), where they keep themselves on stones and actively swim when disturbed.Comparison. Based on larval characters only, Kaltenbach & Gattolliat (2019) established the Labiobaetis difficilis group of species which includes L. difficilis Müller-Liebenau 1984 from continental Malaysia, L. roulade Kaltenbach & Gattolliat 2019 from Indonesian Sumatra and L. weifangae Kaltenbach & Gattolliat 2019 from Indonesian Sumatra and Sumbawa. This group differs from all other Labiobaetis by the following combination of characters: A) dorsal surface of labrum with submarginal arc of feathered setae; B) 2nd segment of labial palp with large, thumb-like distomedial protuberance; C) all 7 pairs of tergalii present; D) paraproct not expanded distally; E) hind protoptera absent. The new species L. ludmilae sp. nov. has all these characters.Larva of L. ludmilae sp. nov. differs from these three species, as well as from all other species of Labiobaetis and most other Baetidae, by the shape of denticles on posterior margins of abdominal terga II–V, which are inclined laterally (Figs. 39, 46–49). In contrast to it, denticles on posterior margins of abdominal terga are directed caudally in L. roulande and L. weifangae (Kaltenbach & Gattolliat 2019: figs 10g, 12c). On the photos of a paratype of L. difficilis kindly sent by Th. Kalenbach, denticles on posterior margins of abdominal terga are also directed caudally (Fig. 40). Besides L. ludmilae sp. nov., denticles of middle abdominal segments are inclined laterally in some representatives of Procloeon Bengtsson 1915 (Kluge 2023: fig. 55).The male imago of the new species L. ludmilae sp. nov. differs from all known male imagines of Labiobaetis by the shape of its gonostylus, which has distal widening of the 2nd segment (Figs 69–70).Molecular data. We obtained a COI sequence of 730 bp length from one of the larval specimens. The GenBank ID for this sequence is PX315513.To compare this sequence with that of other species of Labiobaetis, a dendrogram was constructed using Bayesian Inference. The final alignment contained 146 sequences, including most Labiobaetis representatives from GenBank (https://www.ncbi.nlm.nih.gov) and several Baetis species as an outgroup. These are sequences listed in our paper about Symbiocloeon (Kluge et al. 2025) plus all sequences reported in the paper about Labiobaetis from Thailand by (Kaltenbach et al. 2025). Sequences were aligned and trimmed in AliView software v. 1.30. Total length of the alignment was 594 bp. Bayesian analysis was conducted using MrBayes, version 3.2.7 (Ronquist et al. 2012), with a model HKY+I+G. Two runs of 10 000 000 generations with four chains (one cold and three heated) were performed. Chains were sampled every 10 000 generations, burn-in was set by default as 0.25. The reconstruction was visualized with FigTree v.1.4.2.In the dendrograms obtained using MrBayes, the sequence from our new species did not cluster with any species of Labiobaetis, demonstrating a separate branch.

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