Dasyhelea (Sebessia) falxa, Brahma & Chatterjee & Hazra, 2023
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publication ID |
https://dx.doi.org/10.3897/evolsyst.7.90973 |
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publication LSID |
lsid:zoobank.org:pub:15FBAE73-903B-4E14-BDE3-CCC2D65AAD81 |
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persistent identifier |
https://treatment.plazi.org/id/D0ABBE88-3364-41BF-B418-85D03543EF81 |
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taxon LSID |
lsid:zoobank.org:act:D0ABBE88-3364-41BF-B418-85D03543EF81 |
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treatment provided by |
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scientific name |
Dasyhelea (Sebessia) falxa |
| status |
sp. nov. |
Dasyhelea (Sebessia) falxa sp. nov.
Type material.
Holotype ♂, India, West Bengal, South 24 Parganas, Dayapur [22°07'25.0"N, 88°50'46.5"E], 23.V.2018, Coll. S. Brahma. Paratype: 1♂, same as before.
Diagnosis.
The only species in the subgenus Dasyhelea Sebessia with an elongated, oval shaped gonocoxite; gonostylus with less sclerotised middle region; basal arms of parameres sickle-shaped and funnel-shaped aedeagus.
Description.
Male adult (n = 2) (Figs 6A-K View Figure 6 , 8D View Figure 8 ). Total body length 2 mm.
Head. Brown in colour. Eyes not separated. Frontal sclerite (Fig. 6A View Figure 6 ) 46-53 μm long and 34.5-39 μm wide, rhomboid, evenly sclerotised moderately, without any apical projection. Flagellum (Fig. 6B View Figure 6 ) pale brown, 0.6 mm long; flagellomere XIII without any distinct apical projection; length ratio of flagellomeres (I-XIII): 24: 14: 13: 12: 12-13: 13: 13: 12-13: 12: 20: 20-21: 28: 35-36; AR 1.0; flagellomeres II-XIII with sensilla basiconica. Clypeus as in figure 6C, with 4 pairs of setae. Palpus (Fig. 6D View Figure 6 ) pale, straw coloured; length ratio of palp segments (I-V): 10: 13-13.5: 14-15: 10-10.5: 12; PR 2.3; palp segment III with 3 capitate sensilla at its basal one third region.
Thorax (Fig. 6E View Figure 6 ). Yellowish brown with pale streaks running laterads. Scutellum with 5 setae.
Wing (Fig. 6F View Figure 6 ). Macrotrichia sparse, RM cross vein broad, M1, Cu and CuA1 more prominent. Wing margin with short, prominent macrotrichia and membrane with reduced macrotrichia at wing membrane. Wing 0.90 mm long, 0.29-0.30 mm wide; CR 0.47-0.53. Costa ending beyond cubital fork.
Legs (Fig. 6G View Figure 6 ). Pale brown in colour. TRI 3.11-3.16, TRII 2.87-3.57 and TRIII 2.77. Hind tibial comb (Fig. 6H View Figure 6 ) with 5 spines where outer one smallest.
Abdomen. Pale brown in colour.
Genitalia (Figs 6I View Figure 6 , 8D View Figure 8 ). Tergite 9 broad apically, inverted dome shaped, 142.5-152 μm long and 145-161 μm wide. Apicolateral processes (Fig. 6J View Figure 6 ) indistinct, with one prominent seta, cercus with a single seta. Sternite 9 (Fig. 6I View Figure 6 ) with 34.5 μm long posteromedian process, 1.47 × wider than length. Gonocoxite stout, with a mesoventral knob like structure, 71-73.5 μm long, 46-53 μm wide at middle, having 6-7 setae on dorsal side. Gonostylus stout, somewhat stumpy, 62-66.5 μm long, 18.5-23 μm wide basally and 7 μm wide apically, somewhat abruptly narrowed, bearing an apical, pale, oval depression; mid region less sclerotised; 2 inwardly directed setae at basal region; 1 dorsal seta at proximal one third length, centered between two lateral setae, ventrally 9-10 prominent setae, subapex bearing 3 setae. Parameres (Fig. 6I View Figure 6 ) with each basal arm 48.5-53 μm long, sickle shaped with 30 μm long projection. Aedeagus (Fig. 6K View Figure 6 ) funnel shaped with 43.5-46 μm long, 53-60 μm wide; basal arm indistinct, 7-9 μm long, enclosing 34.5-39 μm wide basal arch; posterolateral arm 27.5-30 μm long, apex recurved inwardly, both basal arm and posterolateral arm highly sclerotised; ventromedian projection bulging laterally and extended beyond posterolateral arm forming finger like apical projection.
Female adult. Unknown.
Pupa and larva. Unknown.
Etymology.
The name, " Dasyhelea falxa " derived from Latinised version of sickle, referring to the sickle-shaped basal arms of the parameres of male genitalia.
Remarks.
The new species shares similarities with D. ona Díaz, Spinelli & Ronderos, 2010 (Argentina) in the shape of the basal arms of the parameres but the shape of projection of parameres, gonostylus and aedeagus are markedly different. It also owes similarities with D. (S.) holosericea (Meigen, 1804) (Estonia, Finland, Poland, Lithuania, France, and Russia) in the structure of the gonostylus and basal arms of the parameres, but differs in the shape of gonocoxite and aedeagus. The shape of the parameres in the new species are quite similar with that of D. caribbeana Spinelli & Wirth, 1984 (Jamaica, Haiti, Panama, Mexico, and France), but the shapes of aedeagus and gonostylus shapes are markedly different. Dasyhelea (S.) pauca Yu and Zhan in Yu et al. 2005 (China) has somewhat similar shaped gonostylus and parameres, but the shape of the aedeagus is contrasting. The blend of characters stated in the diagnosis validates D. (S.) falxa as a new member of this subgenus.
Distribution.
The specimens were collected from the Deltaic Proper of Gangetic West Bengal at an altitude of 8 meters above sea level - new species from India.
Ecological notes.
Imagines of Dasyhelea (S.) falxa sp. nov. were captured in proximity of shrub vegetation, close to a brackish water river (Fig. 2D View Figure 2 ) when the air temperature was 33-35 °C and the relative humidity was 80-82%.
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