Thalerosphyrus lannaae Srinivasan & Ang 2026, sp. nov.

Thalerosphyrus lannaae Srinivasan & Ang sp. nov. Figs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 Materials examined. Holotype (on slide): • 1 male larva (ZRCENT 00020491); China, Yunnan, Mengla County [勐腊县], Mohan Town [磨憨镇], slightly muddy river by east of roadside, c. 2 km north of Shangyong Village [尚勇村]); 21°15'41"N, 101°42'58"E; ~ 735 m ASL; coll. Cheng L., 23 May 2000. GenBank Accession Code (PX 640218). Paratype (in ethanol): • 1 female larva (ZRCENT 00020492); 20 km north along highway G 213 from SiMao District [思茅区], small clear flowing hill stream with sand and gravel bottom (pH 7.9), in ravine c. 450 m east of the highway; 22°53'66"N, 101°02'84"E; ~ 1400 m ASL; coll. Tan H. H., 20 May 2000. Diagnosis. Larval diagnostic characters of Thalerosphyrus lannaae sp. nov. are as follows: i) hypopharyngeal superlinguae with long, simple setae extending to concave margin (Fig. 7); ii) maxilla with c. 16 comb-shaped setae on the crown (Fig. 11); iii) inner and outer margins of labial glossa straight near apex (Fig. 13); iv) pronotum slightly expanded laterally and posteriorly (Fig. 2); v) dorsal surface of hind femur with numerous distinctly pointed ‘ arrow-shaped’ setae (Fig. 19); vi) abdominal posterolateral projections strongly developed, reaching maximum size on segment VIII (Fig. 23); and vii) tergalius I elongated and asymmetrical, c. 1.8 × wider than long (Fig. 24). Descriptions. Mature nymph. Measurements. Body length: 4.6–4.8 mm (Fig. 1), Cerci length: 6.5–6.7 mm. Coloration. General coloration yellowish brown (Fig. 1). Head mostly yellowish, pronotum yellowish, anterior submedian region with dark brownish transverse band and mesonotum yellowish with sutures remain dark brownish (Fig. 2). Femur of all legs with dark brownish maculae near the distal apex, tibia of all legs pale and medial part remains yellow. Abdominal terga mostly yellowish brown, terga I – V dark brownish, tergum VI with conspicuous dark brownish posteromedial stripes, terga VII – X anterior margin with diffusive light brownish streaks at medial, submedial, and lateral areas (Fig. 4); sterna light (Fig. 3), with dark brownish markings medially in sternum IX. Caudalii coloration interchanges from pale to dark brownish band for every 4–5 segments (Fig. 1). Shape and setation. Head. Labrum. Laterally elongated, c. 3.6 times wider than long, anterolateral margins elongated, tapering into a somewhat smooth rounded apices; dorsal surface and anterior margin with numerous long, thin hair-like setae (Fig. 5). Hypopharynx (Fig. 6). Lingua with a tuft of few small, simple setae medially; superlinguae with long, simple setae up to the concave margin (Fig. 7). Left mandible (Fig. 8). Inner margin of incisor serrated with c. 7 teeth; kinetodontium trifid or quadrifid, apically with few setae and below the inner margin c. 8 fimbriate setae present. Right mandible (Fig. 9). Inner margin of incisor serrated with c. 9 teeth; kinetodontium trifid, apically with few setae and below the inner margin c. 11 fimbriate setae present. Maxilla (Fig. 10). Galea-lacinia with long, thin simple setae across the inner margin; crown with c. 16 comb-shaped setae (Fig. 11); maxillary palp three segmented; maxillary palp segment I with a row of few small, thin, simple setae on the inner margin and outer margin with rows of long, simple setae; segment III subtriangular and bluntly pointed in the apex. Labium (Fig. 12). Glossae rhomboid; inner and outer margin remains straight near the apex (Fig. 13). Thorax. Pronotum wider than the head, slightly expanded posteriorly and laterally, much wider than the head and basally fused to the mesonotum (Fig. 2). Legs. Forefemur (Fig. 14) with a submarginal row of stout, spine-like setae on the distal 3 / 4 th area of outer margin and inner margin entirely covered with a submarginal row of stout, spine-like setae; dorsal surface with numerous spatulate setae (Fig. 15). Foretibia mostly bare in the outer margin and inner margin with 4–5 small, spine-like setae. Midfemur (Fig. 16) with submarginal rows of stout, spine-like setae on both outer and inner margins (Fig. 17). Midtibia with a row of hair-like setae on the outer margin and inner margin with 3–4 small, spine-like setae. Hind femur (Fig. 18) with submarginal row of stout, spine-like setae on both outer and inner margins, dorsal surface with clearly pointed arrow-shaped setae (Fig. 19). Hind tibia (Fig. 20) with a row of c. 3 stout, spine-like setae in the outer margin along with a row of thin setae in marginal position (Fig. 21) and submarginal area with c. 6 stout, spine-like setae. All tarsi mostly bare, with outer margins entirely covered with dense setation; tarsal claw with 3 small denticles (Fig. 22). Abdomen. Posterolateral projections absent on abdominal segment I, weakly developed on segments II – IV, moderately developed on segment V and reaching their maximum size on segment VIII (Figs 23, 28). Tergalii. Tergalius I elongated and asymmetrical, c. 1.8 times wider than long (Fig. 24); tergalii II – VI asymmetrical and wider than long; tergalius VII oval and symmetrical (Fig. 25). Posterior margin of tergite IV with irregularly pointed, small to long triangular spines and a few microdenticle rows (Fig. 26). Imago. Unknown. Etymology. The new species is named after Dr Lanna Cheng, a marine insect specialist who was part of the Xishuangbanna (Yunnan, PR China) NUS Biological Expedition in 2000 and collected the holotype specimen of the new species. Distribution. China (Yunnan Province). Taxonomic remarks. Thalerosphyrus lannaae sp. nov. belongs to the T. sinuosus group (Braasch and Soldán 1984), characterised by elongated posterolateral projections on abdominal terga VI – VIII. Within the group, it shares two characters with T. thailandensis, T. bengalensis, and T. sartorii: (i) a reduced number of comb-shaped setae on the crown of maxillae and (ii) presence of only a few microdenticles on the posterior margin of tergite IV. The new species is distinguished from T. thailandensis by its strongly developed posterolateral projections on terga VI – VIII (moderately developed in T. thailandensis; Sutthacharoenthad et al. 2019: fig. 4 c, to poorly developed in T. meghalayensis; Selvakumar et al. 2017: fig. 3), the presence of numerous pointed arrow-shaped setae on the dorsal surface of the hind femur (spatulate and rounded or truncate in T. thailandensis; Sutthacharoenthad et al. 2019: fig. 7 d), and the long, simple setae on the superlinguae that extend to the concave margin (very small setae apically in T. thailandensis; Sutthacharoenthad et al. 2019: fig. 12 e). Moreover, T. lannaae sp. nov. is distinguished from the other two aforementioned Indian species by the greatly developed posterolateral projections of the abdomen in T. sartorii, and by the distinctly concave margins of the glossae in T. bengalensis. Key to the known larvae of Thalerosphyrus Eaton, 1881 from the Oriental region