Melanoneura agasthyamalaica Chandran, Chandran, Jose & Koparde, 2024

Chandran, A. Vivek, Chandran, Reji, Jose, Subin K., Payra, Arajush & Koparde, Pankaj, 2024, Melanoneura agasthyamalaica sp. n. (Odonata, Platycnemididae) from the Western Ghats, India, International Journal of Odonatology 27, pp. 213-226 : 216-223

Melanoneura agasthyamalaica Chandran, Chandran, Jose & Koparde sp. n.

Type material

Holotype

♂, labelled as “ Holotype Melanoneura agasthyamalaica Chandran, Chandran, Jose, Koparde , India, Kerala, Thiruvananthapuram, Aryanad [8.615783°N, 77.105825°E], elevation 117 m above MSL, 20 v 2024, Coll. A. Vivek Chandran ” ( WGRC, ZSI).

Paratypes

2 ♂ and 1 ♀, data as holotype .

Diagnosis

Male Melanoneura agasthyamalaica sp. n. can be dis- tinguished from its only congener, M. bilineata , by the following features: posterior lobe of prothorax with a more rounded posterior margin (posterior lobe of prothorax with a relatively straight posterior margin in M. bilineata ). Mesostigmal plates flat (mesostigmal plates curled at the tips in M. bilineata ) ( Figures 3 & 4 ). Pt in FW squarish, covering just over one cell (Pt in all wings rectangular, covering two cells in M. bilineata ) ( Figure 5 ). Cerci more elongated, as long as paraprocts, with a more pointed spine (cerci shorter, falling just short of paraprocts, with a more rounded spine in M. bilineata ) ( Figures 6 & 7 ). The outer processes of the distal segments of genital ligula are spatulate in both taxa. The inner processes are shallowly divided in the new taxon and deeply divided in M. bilineata ( Figures 8 & 9). The following differences in body markings are also seen, but these could be individual variations and the consistency of these characters must be confirmed by examining more specimens: in dorsal view, black marking on anterior and middle lobes of prothorax makes an acute, ‘V’ shaped mark in the new species (black marking on anterior and middle lobes of prothorax much broader, like a patch, in M. bilineata ); the dorsal black marking extends anteriorly and ventrolaterally without interrupting lateral blue markings in the new species (in M. bilineata , the dorsal black marking interrupt lateral blue markings anterolaterally). The contrast in the shape of mesostigmal plates, with straight margins in the new species and curled margins in M. bilineata , is also visible more clearly in the lateral view of prothorax ( Figures 10 & 11 ). In dorsal view, thinner antehumeral stripes with relatively smooth borders for the new species (broader antehumeral stripes with ragged borders in M. bilineata ). In lateral view, antehumeral stripes slightly curve inside at anterior end for the new species (antehumeral stripes have club-like tips at anterior end in lateral view in M. bilineata ) ( Figures 12 & 13 ). Blue markings on S8 and S9 more restricted basolaterally in the new species (blue markings on S8 and S9 occupy more space basolaterally in M. bilineata ) ( Figure 14 ). The differences in body markings of males, other than that of prothorax, are very minor and may be clinal or may vary according to age of the individuals. In females, which are paler and shorter versions of the males, the size of Pt on FW and the shape of the prothoracic marking, similar to those in males, are reliable features to separate these two species.

Description of holotype ( Figures 15 & 16 )

Male. TL 51.5 mm; AB 41 mm; FW 27.5 mm; HW 27 mm.

Accession number: ZSI/WGRC/I.R.-INV.27250.

Head ( Figure 16 B ). Middle and lateral lobes of labium ashy white, tipped dark brown; labrum, anteclypeus, and postclypeus metallic blue-black, outer margin of postclypeus produced into small, blunt horns on both ends; bases of mandibles black; genae blue, with a black band which is confluent with the black of clypeus; antefrons black, but the blue of genae spreads onto it narrowly; postfrons fully black; rest of the head black, including the undersurface; lower 2/3 rd of eyes ultrama- rine blue, capped with black; ocelli translucent white; scape and pedicel of antennae fully black, tip of flagel- lum pale yellow.

Prothorax ( Figures 10 A & 11 A ). Posterior lobe fully black, rounded, and simple; middle lobe black dorsal- ly, but with a short ingress of azure blue from anterior lobe, making a black ‘V’ shaped mark at their junction; propleuron azure blue; anterior lobe almost fully azure blue, but with short ingress of black from middle lobe at two points dorsolaterally.

Pterothorax ( Figures 12 A & 13 A ). Jet black marked with azure blue as follows: middorsal carina and mesepisternum black; rather thin blue antehumeral stripes with relatively smooth borders; mesepimeron black; metepisternum blue; over 3/4 th of mesinfraepisternum black, with only its lower end blue; metepimeron and metinfraepisternum blue; black stripe through meta- pleural suture broad in the middle and narrow at both ends, narrowest at anterior end; underside of thorax pale white.

Legs ( Figure 16 G ). Black; coxae and trochanters blue; extensor surface of tibiae blue.

Wings ( Figure 16 C & F ). Hyaline; Ab absent; Pt black, squarish, covering slightly over one cell in FW, rectangular, covering two cells in HW, braced between thick, black nervures; Ax 2 in all wings; Px 21 in both FW, 20 in lef HW, 21 in right HW.

Abdomen. Black, marked with blue as follows: S1 broad- ly blue, with thick basal and thin apical black margins; S2 ventrolaterally blue; S3–S6 with small basal lunules on dorsum, decreasing in size; dorsal lunules almost in- visible on S7; S8 and S9 entirely blue on dorsum, except for very narrow basal annules, laterally blue, but black at an angle towards the base; S10 blue on dorsum, black laterally.

Caudal appendages. Black, twice as long as S10, cov- ered irregularly with hair-like pale white setae; cerci broad at base, bifurcates at 2/3 rds its length to produce an upper spine with an elongated blunt tip, remaining structure produced downwards and then straight, ending in rounded tip; paraprocts broad at base, sloping downwards and tapering gradually, tip conical and di- rected upward.

Paratype 1 ( Figure 17 )

Male. TL 50 mm; AB 40 mm; FW 27.5 mm; HW 27 mm.

Accession number: ZSI/WGRC/I.R.-INV.27251.

The prothoracic marking is bluer, making a more distinct ‘V’ shape at the anterior and middle lobe juncture. Px 18 in both FW and 17 in both HW; other characters similar to the holotype.

Genital ligula. As shown in the figure, proximate segment broad and curved; middle segment short and fea- tureless; distal segment produced into four filaments, the two outer ones ending in spatulate tips, the two inner ones thick, curved upwards like a bull’s horns.

Paratype 2

Male. TL 53 mm; AB 43.5 mm; FW 28.5 mm; HW 28 mm. Accession number: ZSI / WGRC /I. R.-INV.27252 .

Px 20 in both FW, 17 in lef HW, and 16 in right HW; other characters similar to the holotype.

Paratype 3 ( Figures 18 & 19 )

Female. TL 41 mm; AB 33 mm; FW 25 mm; HW 24.5 mm. Accession number: ZSI/WGRC/I.R.-INV.27253.

Similar to the male, but considerably shorter, the blue on thorax and abdomen paler; eyes with a light green tinge at the middle; abdomen shorter and more robust; basal lunules absent on dorsum of S7; S8 and S9 with blue nose-like markings on dorsum and a wide apical border on S8, a narrower one on S9; dorsum of S10 with a pale blue mark.

Caudal appendages. Black; cerci short and conical; vul- var scale dark brown, tipped with lighter brown, not reaching the end of abdomen; ovipositor light brown, robust.

Remarks

Fraser (1924) mentions that M. bilineata was described based on “a single imperfect teneral male, taken in Sidapur, Coorg” (now Siddapura, Kodagu in Karnataka State), with its last four abdominal segments missing. However, an examination of this specimen in the Natural History Museum, London showed that it is a female ( Figure 20 ). Melanoneura bilineata specimens collected for this study were from the same landscape (Wayanad) as its type locality (Coorg). They exactly match the descriptions of both sexes given by Fraser later (1933).

The type locality of Melanoneura agasthyamalaica sp. n. is a home garden dominated by rubber trees and areca nut palms bordering the Peppara Wildlife Sanctuary ( Figure 21). It has numerous canals through which water flows into the Karamana River seasonally. These canals have a good herbaceous cover on their banks and provide habitat to endemic odonate species like Protosticta gravelyi Laidlaw, 1915 , Caconeura risi (Fraser, 1931) , Elattoneura souteri ( Fraser, 1924) , and Merogomphus tamaracherriensis Fraser, 1931 . The type locality is probably not the finest habitat of M. agasthyamalaica sp. n., but retains characteristics like good vegetation cover and clean flowing water that support its survival. Most features that separate the new species from M. bilineata become noticeable only when a specimen is examined closely, but as per current knowledge, the ranges of these two species do not overlap. The previous records of M. bilineata from the Aghastayamalai landscape must be reexamined to confirm the distribution of both species in the Western Ghats.

Genetic analysis

Genetic analysis using COI gene sequences, considered conventionally for DNA barcoding, revealed 7.2–7.4% difference between M. agasthyamalaica sp. n. and M. bilineata . The phylogenetic tree reveals that both species are sister clades belonging to Melanoneura group and are evolutionarily closely related to Esme group ( Figure 22 ).

Etymology

The species epithet agasthyamalaica is derived from the Agasthyamalai Biosphere Reserve of the Western Ghats, the landscape from where this species is first described.

Till now, specimens of this species have been studied only from the type locality (Aryanad, Thiruvananthapuram, southern Western Ghats), but it is known to occur in the Ponmudi hills (8.738679° N, 77.121974° E, 427 m a.s.l.) and Bonacaud (8.680735° N, 77.167329° E, 571 m a.s.l.) in the Agasthyamalai hills through photographic records ( Figure 23 ). The shape of the posterior lobe of prothorax and mesostigmal plates helped in identifying the new species from close-up photographs taken in the wild. Melanoneura agasthyamalaica sp. n. could be present in favourable habitats throughout the Agasthyamalai hills, as these form a continuous chain of forested hills in the southern Western Ghats.

Flight season

Recorded from March to October.

Natural history

Most observed individuals of M. agasthyamalaica sp. n. were seen perched singly in shade, near canals or small streams. They occasionally made short sallying flights afer dipteran insects, returning to their perches to con- sume their prey. They were active even during rain. Females could be seen only while mating.

Figures

Figure 3. Posterior lobe of prothorax and mesostigmal plates. A – Melanoneura agasthyamalaica sp. n. ♂; B – M. bilineata ♂.

Figure 4. Line sketches showing the posterior lobe of pro- thorax and mesostigmal plates. A – Melanoneura agasthyamalaica sp. n. ♂; B – M. bilineata ♂.

Figure 5. Pterostigma of right FW. A – Melanoneura agas- thyamalaica sp. n. ♂; B – M. bilineata ♂.

Figure 6. Lef lateral view of caudal appendages. A – Melano- neura agasthyamalaica sp. n. ♂; B – M. bilineata ♂.

Figure 7. Dorsal view of caudal appendages: A- Melanoneura agasthyamalaica sp. n. ♂, B- M. bilineata ♂.

Figure 10. Dorsal view of prothorax and mesostigmal plates. A – Melanoneura agasthyamalaica sp. n. ♂, B- M. bilineata ♂.

Figure 11. Lef lateral view of prothorax and mesostigmal plates. A – Melanoneura agasthyamalaica sp. n. ♂; B – M. bi- lineata ♂.

Figure 13. Lef lateral view of pterothorax. A – Melanoneura agasthyamalaica sp. n. ♂; B – M. bilineata ♂.

Figure 14. Lef lateral view of terminal segments of abdo- men: A – Melanoneura agasthyamalaica sp. n. ♂; B – M. bi- lineata ♂.

Figure 16. Melanoneura agasthyamalaica sp. n. holotype ♂. A – Habitus; B – head; C – wings; D – dorsal view of caudal ap- pendages; E – lateral view of caudal appendages; F – close-up of wing showing absence of anal bridge; G – legs.

Figure 17. Melanoneura agasthyamalaica sp. n. paratype ♂. A – Habitus; B – dorsal view of head, prothorax and pterothorax; C – lef lateral view of caudal appendages; D – dissected genital ligula.

Figure 18. Melanoneura agasthyamalaica sp. n. ♀ in habitat.

Figure 19. Melanoneura agasthyamalaica sp. n. paratype ♀. A – Habitus; B – head; C – lef lateral view of thorax; D – dorsal view of terminal segments of abdomen; E – ventral view of terminal segments of abdomen. Distribution

Figure 20. Melanoneura bilineata ♀ holotype in the Natural History Museum, London. A – Dorsal view with labels; B – lef lateral view. Released under creative commons license CC-BY-4.0. © The Trustees of the Natural History Museum, London.

Figure 22. The consensus phylogenetic tree reveals that M. bilineata and M. agasthyamalaica sp. n. are sister taxa. Nodal val- ues indicate bootstrap support. The scale represents the nucleotide substitutions per site. The tree is rooted to Trithemis spp.

Figure 23. Map showing the type locality and photographic records of Melanoneura agasthamalaica sp. n.