Mortonagrion indraneil, Dow, Rory A., 2011

Dow, Rory A., 2011, Mortonagrion indraneil spec. nov. from Borneo, and a redescription of M. arthuri Fraser (Odonata: Zygoptera: Coenagrionidae), Zootaxa 3093, pp. 35-46 : 42-44

Mortonagrion indraneil sp. nov.

( Figs. 3, 4 , 10 , 12 , 14, 16 , 18, 20, 22, 24 , 31, 32 )

Mortonagrion amoenum (Ris) ; — Lieftinck (1935: 12, part, W. Borneo); — Lieftinck (1937: 104, part, Ƥ W. Borneo); — Lieftinck (1948: 285, part, distribution); — Lieftinck (1954: 70, part, W. Borneo).

Mortonagrion amoena (Ris) ; — Orr (2003: 39, 89).

Mortonagrion new sp.; — Dow & Unggang (2010: 1354, 1357, Table 1, records Binyo Penyilam, Sarawak).

Type material. Holotype: 3 (SAR06_COE343), Malaysia, Sarawak, Samarahan division, Kota Samarahan area, old UNIMAS campus, disturbed peatswamp forest, N 1.461º, E 110.453º, 24 i 2006 leg. RAD, RMNH. Paratypes: Malaysia, Sarawak (all leg. and coll RAD unless noted otherwise): 3 3, Kuching division, Matang Road, disturbed peatswamp and old rubber garden, 23 i 2006; 3, same data, leg. G.T. Reels; 2 3 (SAR09_10_COE25–26), same location, 27 x 2009; 3 (SAR09_10_COE78), same location, 28 v 2010; 3 (SAR09_10_COE90), same data, leg. G.T. Reels; 2 3 (SAR09_10_COE85–86), same location, 30 v 2010; Ƥ (SAR09_10_COE113), same location, 5 vi 2010; 3 (SAR05_COE152), Ƥ (SAR05_COE153), Samarahan division, Kota Samarahan area, old UNIMAS campus, disturbed peatswamp forest, 30 v 2005; 6 3 (SAR05_COE154, 157–161), 3 Ƥ (SAR05_COE155, 162–163), same location, 2 vi 2005; 7 3 (SAR06_COE344–347, 377–378), 7 Ƥ (SAR06_COE349–353, 348, 553), same location, 24 i 2006, leg. G.T. Reels & RAD; 6 3 (SAR07_8_COE84–87, 308, RMNH _INS_ 229067 in ethanol), Ƥ (SAR07_8_COE88), same location, 25 ii 2008; 2 3 (SAR09_10_COE134–135), same location, 7 vi 2010; 3 (SAR07_8_COE89), 2 Ƥ (SAR07_8_COE90–91), Samarahan division, road to Simunjan, highly disturbed peatswamp forest, 16 ii 2008; 3 (SAR06_COE23), Bintulu division, Sarawak Planted Forest Project ( SPFP), Binyo Penyilam Conservation Area, disturbed peatswamp forest, 8 iii 2006; Ƥ (SAR06_COE328), same location, 10 iii 2006; 4 3 (SAR07_8_COE55–58), same location, 27 i 2008; 5 3 (SAR07_8_COE59–62, 92), 6 Ƥ (SAR07_8_COE93–98), same data, leg. R. Ragai; Ƥ (SAR07_8_COE405), same location, 28 i 2008; 6 3 (SAR07_8_COE497–502), Ƥ (SAR07_8_COE503), same location, 8 x 2008; Ƥ (SAR07_8_COE494), Bintulu division, SPFP, Bukit Sarang Conservation Area, mosaic of low pH and freshwater swamp forest, 12 x 2008; 10 3 (SAR06_COE181–185, 214–218), 2 Ƥ (SAR06_COE186–187), Miri division, Loagan Bunut National Park, Hydrology Trail, disturbed peatswamp forest, 4 iv 2006, leg. G.T. Reels & RAD. Indonesia, Kalimantan Barat, Singkawang area (all in RMNH): Ƥ, road to Tjapkala, 19 v 1933, leg. L. Coomans de Ruiter; Ƥ, road to Tjapkala, swamp forest, 16 i 1934, leg. L. Coomans de Ruiter. Paratypes in RMNH and the authors collection.

Etymology. Indraneil , a noun in apposition. Named for Professor Indraneil Das, who first introduced G.T. Reels and the author to the UNIMAS peatswamp forest where the holotype was collected.

Description of holotype male. Head: Labium entirely pale. Labrum blue except for a pair of basal, lateral small brown spots. Clypeus blue. Mandible bases blue along outer and upper margins, elsewhere dirty pale brown. Ocelli whitish, antennae with pedicel brown, rest of dorsum of head black except for a pair of large bilobed pale blue postocular markings ( Fig. 3 ), longitudinally orientated, running close to the eye margin but separated from it.

Thorax: Prothorax entirely black and dark brown. Posterior pronotal lobe with lateral parts very narrow, middle part disc shaped in dorsal view. Synthorax: Mesepisternum bronzy black except for a pair of narrow blue antehumeral stripes ( Fig. 12 ), widely separated into two parts, the anterior part widest near prothorax, narrowly separated from the mesostigmal plates, tapering gently with an irregular margin, and occupying ca one-fourth of the length; posterior part shorter, occupying ca one-fifth of the length and terminating shortly before antealar carina. Mesepimeron almost entirely bronzy black. Metepisternum largely occupied by an obscure pale marking, upper margin irregular and diffuse over most of its length ( Fig. 14 ), only well defined near the wing bases. Metepimeron almost entirely dirty pale yellow. Venter of synthorax pale. Mesinfraepisternum black except a narrow stripe along the lower margin; metinfraepisternum entirely dirty pale yellow. Legs with coxae and trochanters pale yellow, femora same except above joints and a dark streak along the flexor surface, this darkest near joint. Tibiae pale except for a dark streak along the upper flexor surface, terminating at the first spine and immediately above tarsi. Tarsi with first segment brown, second pale except distally, third pale in basal half, brown in distal half, claws pale at base becoming darker towards tips. Wings as for the genus, with 9 Px in left Fw, 10 in right, 7 Px in Hw. Fw quadrilateral with costal side slightly more than half rear side, slightly longer than proximal side and just longer than distal side; Hw quadrilateral with costal side just over two-thirds rear side, ca three times proximal side, which is very slightly shorter than distal side. Three postquadrilateral cells except left Hw, where a cross vein is missing so that there are only 2 such cells. Pt pale brown, with a narrow pale margin variably developed, covering slightly less than one underlying cell.

Abdomen: Largely brown, darker above, paler at sides, with pale markings as follows. S1 with a small lateral blue streak, based on the posterior carina and extending backwards for slightly less than half the segment. S2 with a narrow blue basal annulus, broadly interrupted dorsally and not continuing much past halfway down the sides. S3–6 with a similar blue basal annulus, becoming cream coloured and expanding on the lower half of the side; on S3–4 only very narrowly interrupted dorsally, blue fading by S4, entirely replaced by cream on subsequent segments, fading and becoming more broadly interrupted dorsally. By S7 this marking reduced to a faint obscure lateral patch. S3–6 also with a diffuse but bright cream coloured lateral marking, occupying approximately the fourth one-fifth of each segment, but becoming smaller on successive segments, segment much darker brown beyond this. S8 ( Figs. 16, 18 ) almost entirely blue dorsally, except for a narrow dark band anterior of the posterior carina and a pair of small brown dots at ca seven-tenths length; blue extending laterally about halfway down, below obscurely pale and dark. S9 ( Fig. 16 ) with basal half blue dorsally, this extending onto apical half as two narrow, irregular, parallel spurs just to either side of the dorsal midline, not reaching the posterior carina; very dark brown elsewhere. S10 entirely very dark brown, apical margin raised up into a central peak dorsally. Cerci shorter than paraprocts, and just longer than S10, of complicated shape ( Figs. 22, 24 ), black with obscure grey areas laterally and white areas interiorly. Paraprocts very dark brown, tapering from base to tip, gently and slightly upturned, tips turned inward. Genital ligula as shown in Fig. 31 .

Measurements (mm): Abdomen without anal appendages 21, superior anal appendage ca 0.3, Hw 12.

Description of female paratype (SAR05-COE153). As male except as noted. Head ( Fig. 4 ): Labrum dark brown. Clypeus dull blue, as is an area adjacent to the clypeus and labrum on the mandible bases, which are grey elsewhere, becoming dirty cream along the lower margin. Dorsum of head dark brown, postocular spots absent.

Thorax: Prothorax dark brown, posterior pronotal lobe short, lateral parts not extending below level of mesostigmal plates, central part short and approximately triangular. Synthorax with black mesostigmal plates raised up, longest laterally, where folded forwards ( Fig. 10 ). Rest of mesepisternum dark brown and black, with pale antehumeral markings similar to male described, but reduced and poorly defined. Mesepimeron entirely dark brown. Metepisternum dark brown above, paler below, with a pair of poorly defined blue markings, one a streak above the spiracle, the other just anterior of the antealar carina. Metepimeron obscurely greyish brown and cream, venter of synthorax dirty cream. Mesinfraepisternum dark brown except a narrow dirty cream stripe above coxa, metinfraepisternum coloured as metepimeron. Legs (left anterior leg missing below trochanter) darker than the male, with coxae and trochanters dirty cream and brown. Femora dark greyish brown on outer surfaces, with more extensive dark areas above the joint on inner surface. Tibiae with dark area below joint, otherwise as male. Wings with 9 (left)–10 (right) Px in Fw, 8 Px in Hw. Fw quadrilateral with costal side equal to distal side, half length of rear side and just longer than proximal side. Hw quadrilateral with costal side one-and-a-half times distal side and proximal side and ca three-fifths rear side.

Abdomen: Similar to male, but darker. S1 entirely dark brown. S2–6 with a pair of small basal dorsolateral blue spots, widely separated on dorsum of S2 but only very narrowly separated dorsally on S3–6; these also on S7–8, but pale cream not blue, and fused dorsally to form single mark ( Fig. 20 ). S2–S8 otherwise dark brown above, with sides dark brown with diffuse paler area on each segment, even less well defined than on male described. S9–10 entirely dark brown, apical margin of S10 as male. Cerci short, dark brown, shorter than S10, paraprocts slightly shorter, ca triangular ( Fig. 32 ), dark brown. Ovipositor dirty cream coloured, valves not extending far past margin of S10, terminating before level of tips of paraprocts.

Measurements (mm): Abdomen without anal appendages or ovipositor ca 18.75 (with cerci 19), Hw 12.5.

Variation in paratypes. Apart from small variations in the size and shape of markings on the head, thorax and abdomen, and size variation, most of the variation within M. indraneil appears to be related to age. Teneral individuals of either sex are pale, with both the ground colour of thorax and abdomen and the colour of paler markings becoming darker with age. Immature males often have the facial markings cream rather than blue, and blue markings on thorax and abdomen very pale, these darken and often become reduced in size with age; the antehumeral markings often disappear entirely. The thorax and abdomen change from pale brown to almost black. In one male from the Matang Road there is no pale marking on S9.

Measurements (mm): Males: Abdomen without anal appendages 18–24.5, but 18–21 typical, Hw 10.5–12.5, 8– 10 Px in Fw, 7–10 Px in Hw. Females: Abdomen without anal appendages or ovipositor 19.5–21, Hw 11.5–13, 9– 10 Px in Fw, 7–8 Px in Hw.

Diagnosis. The male is easily separated from all other species by the form of its cerci, in particular by the distinctive finger-like projection ( Fig. 24 ) which is not present in any other species. The female is separated from all species except M. amoena by the combination of very short posterior pronotal lobe and raised, forward folded mesostigmal plates. In M. amoena ( Fig. 8 ) the central part of the posterior pronotal lobe forms a more distinct peak which is directed upwards, exposing the inner ends of the mesostigmal plates, which are folded rearwards whilst the outer ends form a low ridge, rather than being the forward folded structures seen in M. indraneil .

Remarks. Lieftinck (1935) recorded M. amoena from Borneo: “of this species I have also received a few specimens from W. Borneo”; he repeated this record in his 1937 paper, with the additional information that only female specimens were available from Borneo. These female specimens are in RMNH (and are listed above); they differ from M. amoena in size and the structure of the pronotal hind lobe and mesostigmal area, and agree exactly with M. indraneil . There is no evidence of the occurrence of M. amoena on Borneo and it should be dropped from the list of species recorded from the island.

Figures

FIGURES 1 – 6. Dorsal view of head of: (1) M. arthuri male; (2) M. arthuri female; (3) M. indraneil holotype; (4) M. indraneil female paratype (SAR 05 _ COE 153). Markings of pronotum, dorsal view, of M. arthuri: (5) male; (6) female.

FIGURES 7 – 10. Prothorax and mesostigmal region of female Mortonagrion (scale bar 100 μm unless otherwise noted): (7) M. alcyone mesostigmal plates in dorsal view; (8) M. amoena posterior pronotal lobe and mesostigmal plates, lateral; (9) M. arthuri posterior pronotal lobe and mesostigmal plates (scale bar 200 μm), lateral; (10) M. indraneil paratype (SAR 06 _ COE 353) posterior pronotal lobe and mesostigmal plates, lateral.

FIGURES 11 – 14. Markings of male synthorax: (11) M. arthuri dorsal; (12) M. indraneil holotype dorsal; (13) M. arthuri lateral; (14) M. indraneil lateral.

FIGURES 15 – 20. Markings of terminal abdominal segments: (15) M. arthuri male dorsal; (16) M. indraneil holotype dorsal; (17) M. arthuri male lateral; (18) M. indraneil holotype lateral; (19) M. arthuri female dorsal; (20) M. indraneil female paratype (SAR 05 _ COE 153) dorsal.

FIGURES 21 – 24. Male anal appendages: (21) M. arthuri dorsal; (22) M. indraneil holotype dorsal; (23) M. arthuri lateral; (24) M. indraneil holotype lateral.

FIGURES 25 – 32. Genital ligula of Agriocnemis, Argiocnemis and Mortonagrion species (scale bar 100 μm): (25) Agriocnemis femina; (26) Argiocnemis rubescens rubeola; (27) Argiocnemis species; (28) Mortonagrion aborense; (29) Mortonagrion alcyone; (30) Mortonagrion arthuri; (31) Mortonagrion indraneil paratype (SAR 05 _ COE 152). Mortonagrion female anal appendages (32) Mortonagrion indraneil female paratype (SAR 06 _ COE 353), scale bar 200 μm.