Ischnura foylei, Kosterin, Oleg E., 2015

Kosterin, Oleg E., 2015, Ischnura foylei sp. nov. (Odonata, Coenagrionidae) from the highlands of Sumatra, Zootaxa 4032 (2), pp. 179-189 : 179-188

Ischnura foylei sp. nov.

( Figs. 2–4 , 5 a–c, 6, 7a–g)

Type material. Holotype: ♂ ( Fig. 4 , 5 a–c), Indonesia, Sumatra, Jambi Province, Danau Gunung Tujuh (Danau Sakti), 1°41'15"S, 101°25'28"E, 1995 m a.s.l., October 2014; deposited in RMNH. Paratypes: 5 ♂, 3 ♀, of which 2 androchromatic ( Fig. 6 ) and one gynochromatic (heterochromatic) ( Fig. 7 a–g), the same data, deposited in RMNH, BMNH and ISEA. The specimens were preserved in a vial of alcohol, some dried afterwards.

Etymology. The species is named after the British philanthropist Christopher Foyle to honour his support for research and conservation of Indonesian rainforests and their biodiversity in both Kalimantan and Sumatra.

Holotype male. A black, azure blue and ochraceous yellowish (on abdomen) damselfly bearing dense light hairs, long on head, thorax and base of abdomen, decreasing in length to the end of abdomen. Since the specimens were preserved in alcohol, their dark colour, black in life ( Fig. 2 a, 3), changed to blackish brown, especially ventrally ( Fig. 4 a–c, 5a–c), while the azure colour changed to whitish blue, but the description below refers to colours in life.

Head ( Fig. 4 e–g): black above ( Fig. 4 e), yellowish white below ( Fig. 4 g), greenish blue and black frontally ( Fig. 4 f). Eyes in life bluish green with a dull violet dorsal side (border of colours indistinct ( Fig. 2 a, 3)). Labium whitish, mentum base brownish, bases of movable hooks with light brown spots, claws brown. Labrum bluish with a broad brown stripe along base with a wavy anterior margin forming three projections, at centre and sides. Mandible bases and genae greenish blue. Anteclypeus greenish blue with a black border at upper margin a pair of deep hollows marked with dark brown spots inside. Postclypeus black. Frons black with an even, arched transverse stripe, contiguous with broad areas of the same colour on genae ( Fig. 4 f). Frons, vertex and occiput black; pair of blue postocular spots, roundish but with irregular margins ( Fig. 4 e). Rear and lower head surface greenish, with two indistinct blackish brown spots on either side of lower surface ( Fig. 4 g).

Thorax: Prothorax black (including anterior lobe) with a brownish border along hind margin. Posterior lobe inconspicuous, very slightly raised, with a wavy, evenly tripartite hind margin; hind margin of prothorax well seen behind posterior lobe, smoothly rounded ( Fig. 4 h).

Mesostigmal plate as shown in Fig. 4 h, with central part more or less rectangular with a transverse central hollow; posterior margin with two short weakly prominent ridges. Synthorax ( Fig. 4 a) dorsum entirely black, antehumeral stripes absent. Mesepisternum black, mesepimeron mostly blue but black at mesopleural suture for 1/3 (below) to 1/2 (above) of its width, and anterior margin broadly black. Lateral suture has only a short and pointed projection of black at its upper end. Inframesepisternum black with lower side broadly greenish blue.

Metepisternum and metepimeron largely azure blue (turning greenish blue at ventral side) but with a broad black stripe along lower margins and metapleural suture. Inframetepisternum greenish blue with a broad black anterior border and narrower borders along other sutures ( Fig. 4 a). Poststernum greenish blue, its anterior margin with a black border with indistinct margins.

Legs ( Fig. 4 a) blackish brown, femora with indistinct yellowish stripes along their lower side; tarsi brownish; protrochanters, trochanters and coxae coloured in brownish black and greenish blue with indistinct border of colours.

Wings hyaline; main longitudinal veins yellowish, other veins brownish. Postnodals 10 on forewing, 9 in hindwing. Pterostigmata ( Fig. 4 c–d) diamond-shaped, those on hindwing slightly smaller, brownish with an indistinct whitish margination; dorsal side of those of forewings azure blue for about distal third.

Abdomen ( Fig. 4 a–c): S1 black with a large subtriangular lateral blue spot towards apex, crossed by a black streak along segment apical carina. S2 black with dark blue metallic lustre on dorsum and smaller subtriangular blue apical spot laterally, not extending beyond subapical carina ( Fig. 4 b). S2–7 bicolorous, brownish black above, dull ochraceous yellow below, with black extended at segment apices to form rings. S8 brownish black with indistinct yellowish latero-proximal spots. S8 and S9 azure blue; S8 with faint black streaks along anterior and posterior margins (the former complete, the latter disappears at lower parts); sternite brownish black but bluish for distal 1/5. S8 with a short, with tapering ends, black streak along anterior margin, a longer black streak along carina at posterior margin, and a pair of very small slanting black strokes on dorsum ( Fig. 4 c, 5a–c). S10 mostly black with a greenish blue metallic lustre at dorsal side, greenish below. Appendages black. S10 cleft deep, V-shaped. Appendages brown at base, black distally ( Fig. 5 a–c).

Cerci short and broad, in dorsal view ( Fig. 5 b,c), with rounded inner angles, skewed towards somewhat projecting blunt outer margins; in lateral view mammiform (as inverted breasts), skewed down with apices very slightly hooked down. Paraprocts long, in dorsal view ca 2.5 times as long as cerci, clawlike, slightly curving towards each other and bluntly hooked; in lateral view straight, blunt, directed up and behind, at ca 45º to body axis ( Fig. 5 a–c).

Measurements (mm). Hindwing 18.5; abdomen 26; total length 33.

Variation in male paratypes. The number of forewing postnodals varies from 10 to 11, in one case 12; that of hindwing varies from 9 to 10. In two males with less developed black markings, twin dorsal black strokes on S10 missing, inframetepisternum blue with all black borders narrow, black stripe along metapleural suture narrow, mesepimeron with a broad black border at ventral side but this border does not continue at metepisternum (this variation is seen in the two males of Figs. 2 a, 3). In a more melanised male, S10 with a broad black tridental stripe along posterior margin ( Fig. 5 c). Ranges of measurements (mm): hindwing 18–19; abdomen without anal appendages 26–28; total length 33–35.

Androchromatic females ( Fig. 3 a, 6). Strongly resemble males, with the following differences. Head ( Fig. 6 i–j); Black tripartite stripe at labrum base narrower. Blue archlike stripe across frons broader. Eyes greener.

Thorax: Prothorax anterior lobe with a broad yellowish transverse stripe ( Fig. 6 e). Mesostigmal plate as in male. Black stripe along metapleural suture narrow. Inframesepisternum half black and half blue; inframetepisternum blue with a narrow black stripe along anterior margin. Mesepimeron broadly bordered with black below, but this border does not continue to metepisternum ( Fig. 6 i–j). Poststernum without an anterior dark border but with a pair of blackish brown indistinct spots at middle. Procoxa with a large blue spot; meso- and metaxoca blue with black anterior borders ( Fig. 6 a). All venation brownish. Postnodals: 11–12 on fore wing, 9–10 on hindwing. Pterostigmata brownish with lighter rims at ventral side, evenly yellowish at dorsal side ( Fig. 6 d).

Abdomen ( Fig. 6 a–c, f–h): S2 with additional small blue anterolateroventral spots ( Fig. 6 a–b). S8 without a black streak along carina at posterior margin. In the two androchromatic paratypes, S9 varies. In one, a version of male pattern with both anterior and posterior black stripes extended (the former with three prominences, the latter with one) ( Fig. 6 f). In the other, S9 black with very large lateral blue spots and small twin irregularly transversal dorsal blue spots ( Fig. 6 g) (S 9 in this female shows the greatest difference from the male pattern). Sternite of S8 blackish; vulvar spine black, well developed. Ovipositor bicolorous, blackish brown above and yellowish below, style brownish ( Fig. 6 h). Cerci blackish, paraprocts blackish above, yellowish below and inside ( Fig. 6 g–h).

Measurements (mm; two specimens). Hindwing 18 and 20; abdomen without anal appendages 25 and 28; total length 32 and 35.

Gynochromatic (heterochromatic) female ( Fig. 2 b–c, 7a–g). An ochraceous green damselfly with a black dorsal pattern, of a common appearance of Ischnura gynochromatic females but with indistinct melanisation at sides of last abdominal segments. Immature, orange gynochromatic females occurred at the type locality as well but were not collected.

Head ( Fig. 7 e–f): black above, greenish below, dull orange behind. Labrum greenish with a wavy black stripe at base. Anteclypeus greenish. Postclypeus black. Frons mostly greenish, with a convex black streak at ventral margin and a black stripe along dorsal margin, so that border of greenish and black colours generally straight but uneven. Antenna 1st segment and apex of 2nd segment greenish, rest of antenna black ( Fig. 7 f). Occiput dull orange behind, narrowly at central part, broadly at sides, but orange does not reach eyes which are bordered with black. Postocular spots bluish, diamond shaped, disposed at border of black and orange ( Fig. 6 e).

Thorax: Prothorax ( Fig. 6 g) anterior lobe yellowish green. Median lobe black dorsally, sides change from greenish below to dull orange above (border of this colour makes upward projections in its distal part). Posterior lobe with a yellowish margin, smoothly tripartite with central part making a more developed smooth projection than in males and androchromatic females and so hides prothorax posterior margin. Mesostigmal plate as in males and androchromatic females, black but with broad greenish ochraceous boders along sides of its posterior margin ( Fig. 6 g). Synthorax ( Fig. 6 a) dull orange above turning greenish below, with a broad black dorsal stripe occupying about halves of mesepisterna; no other black markings. Coxa and protrochanters yellowish, trochanters and femora brown with yellowish ventral side; tibiae yellowish with blackish stripes at outer sides; tarsi brownish, with lighter claws.

Wings hyaline; venation brownish. Postnodals 11–12 on fore wing, 9–10 on hindwing. Pterostigmata yellowish to brownish.

Abdomen ( Fig. 7 b–d): Ochraceous greenish with dorsal black stripe along S3–10, which expands ventrally at S3–9 along subapical carina producing indistinct half-rings. S1 without black markings, S2 with a dorsal cupshaped black spot occupying ca posterior 40% of segment length. S6–7 with irregular brown subapical melanisation on lower tergite halves; on S8 this melanisation occupies ca distal 3/4 of tergite length; on S9 appearing along both proximal and distal tergite margins. In one of specimens photographed ( Fig. 2 c), this subventral melanisation is more developed. Cerci brownish, paraprocts and ovipositor ochraceous ( Fig. 7 d). Tergites blackish but ochraceous at apex; vulvar spine ochraceous ( Fig. 7 d).

Measurements (mm). Hindwing 20; abdomen without anal appendages 28; total length 34.

Diagnosis. The species is unique in the genus by virtue of the colour pattern of its males: coloured black and blue (with a green hue only on face and lower part of synthorax), antehumeral stripes absent, continuous black stripes along the metapleural and poststernal sutures (but a light poststernum), conspicuous blue lateral spots distally at S1 and S2, blue S8 and S9. Structurally the new species males are close to those of the widespread Ischnura senegalensis (Rambur, 1842) , here illustrated by specimens from Lombok ( Fig. 5 d–e, 7h). The new species differs from it in having the structure of the prothorax, with posterior lobe not raised ( Fig. 4 a, h), and the long paraprocts directed back and up ( Fig. 5 a). A notable similarity of the new species to I. senegalensis is the metallic blue lustre on the dorsum of S2 ( Fig. 2 a, 4a–b). The main structural difference from I. senegalensis is the shape of the cerci. In the new species they are skewed laterally in dorsal view ( Fig. 5 b), strongly resembling those of Ischnura elegans (Vander Linden, 1820) , and nearly mammiform, just skewed down in lateral view ( Fig. 5 c), while in I. senegalensis they are truncated nearly straight in dorsal view ( Fig. 5 e) and strongly hooked down in lateral view ( Fig. 5 f). The dorsal cleft of S10 is deeper and more acute than in I. senegalensis ( Fig. 5 b). The synthorax of the new species has an azure blue ground colour with a green hue only in ventral part ( Fig. 2 a, 3) while in I. senegalensis the synthorax is more green than blue. It is noteworthy that the new species is much larger than I. senegalensis : hw 18–20 mm, 10–12/9–10 (fw/hw) postnodals versus hw 13–16 mm, 8–9/6–7 postnodals in I. senegalensis .

I. elegans differs structurally from the new species in the prothorax posterior lobe with a very prominent central part, and the paraprocts directed more back than up.

The androchromatic females have the same unique appearance ( Fig. 3 , 6 a–c) as the males apart from an additional pair of blue anterolateral spots on S2 and the dorsum of S9 which is more and variably black ( Fig. 6 f–g). The gynochromatic females differ from I. senegalensis in a more developed (as in males) trilobation of the prothorax posterior lobe, with the central part rounded and moderately protruding behind ( Fig. 7 g), while in gynochromatic females of I. senegalensis the posterior lobe central part is very gently rounded, almost straight ( Fig. 7 h). Besides, the gynochromatic females of the new species are considerably larger (hw 20 mm in the studied specimen, postnodals 11–12/9–10 versus hw 14–16 mm, postnodals 9/ 7 in I. senegalensis ).

Habitat. The lake Danau Gunung Tujuh (‘Lake of Seven Mountains’) also known as Danau Sakti (‘Mystic Lake’), resides in an extinct volcanic crater among evergreen forest at 1995 m a.s.l.. Damselflies of the new species were abundant in sedges seen at the left of Fig 1 . This species was quite abundant at the lake but was the only damselfly species observed there; in addition, metallic green dragonflies (perhaps Procordulia sp.) and, at a forest stream nearby, a female of Anaciaeschna jaspidea (Burmeister, 1839) and a teneral male of Macromia moorei Selys, 1874 , were photographed.

Distribution. So far known only from the type locality.

Figures

FIGURE 1. The type locality and habitat of Ischnura foylei: Danau Gugung Tujuh (Danau Sakti), Jambi Province, Sumatra, Indonesia (photo by J. Holden).

FIGURE 2. Ischnura foylei at the type locality: a—males; b – c—gynochromatic (heretochromatic) females (photos by J. Holden).

FIGURE 3. Copulating pairs of Ischnura foylei in the type locality: a—involving an androchromatic female; b—involving a gynochromatic (heterochromatic) female (photos by J. Holden).

FIGURE 4. Details of the holotype male of Ischnura foylei: a—habitus of head, thorax and S 1 – 3 of abdomen, lateral view; b— S 1 – 2 of abdomen, lateral view; c—S 6 – 10 of abdomen, lateral view; d—pterostigmata; e—head, dorsal view; f— ditto, frontal view; g— ditto, ventral view; h—posterior lobe of prothorax and mesostigmal plate, dorsal view. Not to scale.

FIGURE 5. End of abdomen of males of Ischnura foylei (a – c) and I. senegalensis (d – e): a – b—holotype of I. foylei; c—the most melanised paratype of I. foylei; d – e—a male of I. senegalensis from Indonesia, Lombok, 7 km NW Mataram, 8 ° 32 ' S, 116 ° 04 ' E, 6 m a. s. l., 22 ii 2014; a – d—lateral view; b – c, e—dorsal view; a – b and d – e in the same scale, c not to scale.

FIGURE 6. Details of androchromatic female paratypes of Ischnura foylei (a – e and j – j—the same specimen; f—the other specimen): a—habitus of head, thorax and S 1 – 3 of abdomen, lateral view; b—S 1 – 2 of abdomen, lateral view; c—S 6 – 10 of abdomen, lateral view; d—pterostigmata; e—prothorax and mesostigmal plate, dorsal view; f, g—end of abdomen, dorsal view; h— ditto, lateral view (note vulvar spine not clearly visible); i—head, dorsal view; j— ditto, frontal view. Not to scale.

FIGURE 7. Details of gynochromatic (heterochromatic) females of Ischnura foylei (a – g—a paratype) and I. senegalensis from Lombok, 7 km NW Mataram (h): a—habitus of head, thorax and S 1 – 3 of abdomen, lateral view; b – S 6 – 10 of abdomen, lateral view; c—end of abdomen, dorsal view; d— ditto, lateral view; e—head, dorsal view; f— ditto, dorsofrontal view; g – hprothorax and mesostigmal plate. Not to scale.