Thraulus vellimalaiensis Vasanth, Subramanian and Selvakumar, 2022
|
publication ID |
https://doi.org/ 10.26515/rzsi/v122/i2/2022/168290 |
|
persistent identifier |
https://treatment.plazi.org/id/2B7587A7-FFBE-9C21-FD53-FDE3FC8679CE |
|
treatment provided by |
Felipe |
|
scientific name |
Thraulus vellimalaiensis Vasanth, Subramanian and Selvakumar |
| status |
sp. nov. |
Thraulus vellimalaiensis Vasanth, Subramanian and Selvakumar sp. nov.
( Figures 74 View Figures 74–79 –88)
Material examined: Holotype: 1 larva, India, Tamil Nadu, Theni, Megamalai WLS, Vellimalai , Bommiyamman River , near Bommarajapuram , 09.61906°N, 077.40639°E, 768 m, 25.ii.2019, coll. M. Vasanth (Reg. No. I /E/522) GoogleMaps . Paratype: 1 larva, (Reg.No.I /E/523) same data as holotype GoogleMaps . 2 larva, India, Tamil Nadu, Theni, Megamalai WLS, Vellimalai , Charlimedu stream, near the Moolavaigai River , 09.58504°N, 077.41904°E, 716 m, 24.ii.2019, coll. M. Vasanth (Reg. No. I /E/524). Types are deposited in SRC/ZSI/ Chennai GoogleMaps .
Description: Mature larva. Body length 9.5–10.5 mm, cerci 5.5–6.5 mm, median filament 7.5 mm ( Figure 74 View Figures 74–79 ).
Head: Head capsule and area between ocelli washed with dark brown; the area between median ocelli and frons pale; median line of vertex pale brown; margins of clypeus parallel. Labrum with posterior margin convex, irregular sparse setae on both dorsal and ventral surfaces, labrum anteromedian emargination broad with undulate medially 2.2x longer than the width ( Figure 75 View Figures 74–79 ). Lingua of hypopharynx with well developed lateral processes, anterior margin shallowly cleft; superlingua slightly developed lateral projection with its arms ( Figure 76 View Figures 74–79 ). Mandibles with sparse lateral setae, prostheca of the left mandible with a stout spine-like setae and outer and inner incisors with 3 denticles each. Right mandible outer incisor with 3 denticles and inner incisor with 2 denticles ( Figures 77 and 78 View Figures 74–79 ). Maxilla with dense stout spines and fine setae on anterior margin, an additional row of 17–18 pectinate setae; outer margin of maxilla with hair-like long setae; palp III segmented, length of segment I 0.5x times length of segment II, outer margin with few hair-like setae; length of segment III 0.3x times shorter than segment II, outer and inner margins with thin hair-like setae, III segment with an apically small tuft of hair-like setae ( Figure 79 View Figures 74–79 ). Labium: glossa with thick plate-like setae on the ventral surface, stout setae on dorsal surface; paraglossa with denser but hair-like stout setae on dorsal surface; segment I of labial palp with thick setae on margins, II segment with setae on outer margin, III segment with thick and fine hair-like setae on outer margin and dorsal surface; III segment apically small cluster of thin setae; segment I length ca. 1.0 times segment II length, segment III length 1.2 times length of segment II ( Figure 80 View Figures 80–86 ).
Thorax: Pronotum brown with black irregular markings on the dorsal surface. Mesonotum brown, median area pale. Foreleg of trochanter with anterior surfaces lite black, and lateral surface yellowish; femora broad, basal femora white, apically lite yellowish mixed with black, tibiae blackish yellow with very sparse and thin setae on inner margin, densely covered with a row of feathered setae and with a row of stout and transverse setae ( Figure 81 View Figures 80–86 ). All legs pale; hind tibiae mixed with denser, thick and feathered setae on the surface; tarsi of all legs with several thick setae on inner margin and sparse setae on outer margins ( Figures 81, 82 and 83 View Figures 80–86 ). Claw with a row of 11-12 denticles, progressively shorter towards the apex ( Figure 84 View Figures 80–86 ).
Abdomen: Abdomen brown mixed with black, with indistinct paired pale submedian spots along the body axis. Terga III–IX with posterolateral projections, terga VIII–IX larger. Sterna is uniformly yellowish. Segments I–VII with gills; gills I slender, lanceolate, ventral lamellae wider than dorsal ( Figure 85 View Figures 80–86 ); gills II–VII similar in shape, with dorsal and ventral lamellae; each lamella elongated-ovate, with entire margins long fimbriate; tracheae of gills slightly clear ( Figures 86 View Figures 80–86 , 87 and 88). Caudal filaments with a whorl of setae on alternate segments; setae shorter than the length of the corresponding segment.
Adult: Unknown.
Etymology: The species named after the type locality of Vellimalai, Megamalai WLS, Theni District, Tamil Nadu, India.
Distribution: Tamil Nadu (Megamalai WLS, Theni). Diagnosis: Thraulus vellimalaiensis sp. nov. can be distinguished from other known species of the genus by the following combination of characters:
• Labrum anteromedian emargination is broad with undulate medially ( Figure 75 View Figures 74–79 ).
• Hypopharynx of superlingua slightly developed, lateral projection with its arms ( Figure 76 View Figures 74–79 ).
• Mandibles are smoothly curved with 2–3 hair-like setae on the anterior margin ( Figures 77 and 78 View Figures 74–79 ).
• Hind tibia with stout pointed setae ( Figure 83 View Figures 80–86 ).
• Claw with a row of 12 denticles, progressively shorter towards the apex ( Figure 84 View Figures 80–86 ).
• Gill I slender, lanceolate, ventral lamellae wider than dorsal ( Figure 85 View Figures 80–86 ).
• Gill II–VII oval, with marginal fringes, tracheae of gills clear slightly ( Figures 86 View Figures 80–86 , 87 and 88).
Habitat: Larvae of the new species were collected in a small sized stream (wide 5–8 m) with stones and gravel,
at an altitude of 768m ( Figures 94 and 95 View Figures 90–95 ). Larvae were associated with Baetis sp. , Heptageniidae ( Afronurus
sp.,), Leptophlebiidae ( Choroterpes sp. ), Caenis sp. ,
Hydropsychidae ( Trichoptera ).
Larval key to the Oriental species of Thraulus Eaton,
1881
1. Abdominal segment I with unilamellate gill… .....… T. femoratus Li, Liu & Zhou, 2006
- Abdominal segment I with bilamellate gill……………………………………..………2
2. Ventral lamella of gill I fimbriate ………..………………………….…....……..…..3
- Ventral lamella of gill I slender or lanceolate ………………………… ... ……. ………. 5
3. Anteromedian emargination of labrum with small, blunt crenation medially…………………………… ………………….……….. T. malabarensis sp. nov.
- Anteromedian emargination of labrum without blunt crenation medially…….………...4
4. Labrum with rectangular median emargination; gills on abdominal segments II–VII similar in size…………………………….. T. gopalani Grant & Sivaramakrishnan 1985
- Labrum without rectangular median emargination; gills on abdominal segments II–VII not similar in size…………..… T. thiagarajani Balasubramanian & Muthukatturja 2019
5. Dorsal and ventral lamella of gill I similar in size.….……………………………...…..6
- Dorsal and ventral lamella of gill I not similar in size ………………...…….…………8
6. Dorsum of middle and hind femora with black, broad markings on distal half; anteromedian emargination of labrum with undulate medially; claw with a row of denticles progressively larger apical ly.........................….... T. fatuus Kang & Yang 1994
- Dorsum of middle and hind femora pale; anteromedian emargination of labrum without undulate medially; median denticles of claw larger than apical…...……………………7
7. Labrum with dense setae near the anteromedian margin; galea-lacinia of maxilla with 19– 20 comb-shaped setae near the anterior margin...… T. macilentus Kang & Yang 1994
- Labrum with sparse setae near the anteromedian margin; galea-lacinia of maxilla with 24– 26 comb-shaped setae near the anterior margin…… T. umbrosus Kang & Yang 1994
8. Anteromedian emargination of labrum with median undulation………………………9
- Anteromedian emargination of labrum without median undulation…………………...11
9. Claw with a row of 13–14 denticles, progressively larger towards apex……………………………… ………………………………... T. plumeus sp. nov.
- Claw with a row of 11–12 denticles, progressively shorter towards apex………………………….……..……………..……................................................10
10. Lateral margin of mandibles smoothly curved with 10–12 simple setae……………………………… ……………………… T. jacobusi Isack et al., 2022
- Lateral margin of mandibles not smoothly curved with 1–2 simple setae……………………………… ………………………….. T. vellimalaiensis sp. nov.
11. Anteromedian emargination of labrum cuspidate medially; claw with a row of 10–11 denticles …………………………………… …….......................… T. cuspidatus sp. nov.
- Anteromedian emargination of labrum not cuspidate medially…….......…...…………12
12. Claw with minute denticles in apical set…………………………..……………...…...13
- Claw without minute denticles in apical set …………………………...........................14
13. Claw with 5 minute denticles in apical set and 10 larger denticles in basal row; segment III of labial palp little longer of segment I..… ……….... T. mudumalaiensis Soman 1991
- Claw with 3 minute denticles in apical set and 8 larger denticles in basal row; segment III of labial palp equal to length of segment II.…....…….. T. bishopi Peters & Tsui 1973
14. Clawwitharowof5bluntdenticles;segment3oflabial palp little more than ¾ length of segment II; segment III of maxillary palp equal to length of segment 2…………………….………….……………… T. demoulini Peters & Tsui 1973
- Claw with a row of 8 blunt denticles; segment 3 of labial palp equal to length of segment II; segment III of maxillary palp more than ¼ length of segment 2........................................................... ............................................... T. amravati sp. nov.
Discussion
Lack of species level morphological and molecular phylogenetic studies in India on the genus Thraulus sensu lato hamper prediction of the probable time of arrival and diversification of this genus in the Indian subregion of the Oriental Realm. However, Peters and Edmunds (1970), Peters and Tsui (1972), and Li, et al., (2006) pointed out that gill shape is correlated with water flow and dissolved oxygen concentration, resulting in an array of structural diversity. Accordingly, two morphological species groups of Thraulus sensu lato have evolved in
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
|
Kingdom |
|
|
Phylum |
|
|
Class |
|
|
Order |
|
|
Family |
|
|
Genus |