A review of the damselfly fauna of the , , with descriptions of two new species (Odonata: Zygoptera: Coenagrionidae)

Ronald A. Englund & Dan A. Polhemus

The Zygoptera biota of the Austral Islands in French Polynesia is reviewed, and two new endemic species are described: Ischnura rurutana endemic to the island of , and Ischnura jeanyvesmeyeri endemic to the island of . Additional notes on coloration and ecological preferences are also given for Ischnura thelmae Lieftinck, 1966, endemic to Rapa, and the occurrence of the widespread species Ischnura aurora Brauer, 1865 on all the high islands in the Australs is briefly noted. Color photographs of adult males are provided for all three endemic Austral Island species, as well as figures of the male wing venation, pterothoracic color patterns, and male secondary genitalia, and the female dorsal pterothorax and lateral terminal abdomen. Scanning electron micrographs of the male abdominal appendages in various views are provided for all three endemic Austral Island Zygoptera species. Photographs are also provided for the breeding habitat and immature stage of I. rurutana. Dr. R.A. Englund*, J. Linsley Gressit Center for Entomological Research, Bishop Museum, 1525 Bernice Street, Honolulu, Hawaii 96817, USA. [email protected] Dr. D. A. Polhemus, Bishop Museum, 1525 Bernice Street, Honolulu, Hawaii 96817, USA. [email protected]

Introduction and both the islands themselves and their aquatic The Zygoptera biota of the archipelagos contained habitats are generally difficult to access. Rapa, for within the modern political province of French example, has no airstrip, and only six or seven ships Polynesia is incompletely surveyed. Although only reach its shores in any given year. These islands have a few named species are recorded from this region, therefore been largely overlooked in terms of fresh- many new taxa are known to us from the Society, water entomological surveys. Marquesas, and Austral islands, based on recent sur- Recent work has now revealed that endemic dam- veys by the authors and colleagues. In this paper, we selfly species occur on three of the high Austral report on two new endemic species from the islands islands: Rurutu, Raivavae, and Rapa. Of the remain- of Rurutu and Raivavae in the Austral chain, and ing high islands in the group, is small, review the Zygoptera fauna of the Austral Archipel- relatively low, has few streams, and is now heavily ago as a whole. disturbed by human occupation; surveys here have The Austral Islands are a hotspot chain lying in the revealed no Zygoptera other than the widespread South Pacific Ocean approximately 500 km south of Ischnura aurora Brauer, 1865. The other high Aus- , and extending for approximately 1500 km tral island, , is the largest in the group, rises in an ESE–WNW direction (Fig. 1). The islands to 422 m, and possesses rocky upland streams suit- composing the Australs are all relatively small, able for endemic damselflies. Surveys to date have

Tijdschrift voor Entomologie 153: 25–40, Figs 1–34. [ISSN 0040–7496]. http://www.nev.nl/tve © 2010 Nederlandse Entomologische Vereniging. Published 1 June 2010.

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o o o 155 W 150 W 145 W o Fig. 1. Map of the Austral 20 S Islands, showing locations of islands discussed in text, and position of the Austal Maria Islands in relation to the Rurutu Rimatara Pacific Ocean as a whole. Tubuai Raivavae

25o S

Rapa MAP AREA

0 500 km

not produced any endemic Zygoptera on this island, tron microscope housed at the National Museum of but we consider it possible that such species may Natural History in Washington, DC. exist, given that Tubuai is now known to harbor an Holotypes and paratypes are deposited either in the endemic genus of aquatic Heteroptera, Tubuaivelia National Museum of Natural History, Washing- (Polhemus & Polhemus 2008). ton, D.C. (USNM) or Bishop Museum, Honolulu, Hawaii (BPBM) as indicated. Material and methods The new species described herein were collected Taxonomy during the course of a comprehensive program of Genus Ischnura Charpentier aquatic biodiversity surveys on the islands of French Polynesia, recently undertaken in cooperation with Ischnura rurutana sp. n. the Délégation à la Recherche in Papeete, and Figs 2, 5, 8, 11–15, 23, 26, 29, 32 funded by that agency, with supplemental funding from the U. S. National Science Foundation. Col- Type material. – Holotype, ?: French Polynesia, lections at a given site were made by visual searching Austral Islands, Rurutu, Puputa Stream, above and hand netting of adults, and dip netting and kick Moerai Town, from water tanks at 64 m eleva- sampling of benthos for immatures. Specimens were tion (22.45016°S, 151.35100°W) upstream to preserved in 75% ethanol, then transported to the 80 m elevation at 20 m-high cascade (23.45041°S, Bishop Museum in Honolulu, Hawaii for detailed 151.35210°W), 23.xi.2003, BPBM-FP 1490, analysis and identification. R.A. Englund (BPBM). Paratypes: French Poly- All measurements are given in mm. Descriptive nesia, Austral Islands, Rurutu: 8 ?, 1 /, same data morphological terminology and associated abbrevia- as holotype (BPBM). tions used herein follow Westfall & May (1996) and Lieftinck (1959, 1966). Because the bright colors Description of these Ischnura fade considerably in specimens Male. Size. Dimensions of holotype: Total length preserved for any period of time, whether dry or in 30 mm; abdomen length 19 mm; fore wing length alcohol, our descriptions of coloration are based on 17 mm; hind wing length 16 mm. Intraspecific notes made from live individuals, dead individuals variation (n = 6): Total length 29–31 mm; abdomen immediately after capture, or photographs of living length 22­–26 mm; fore wing length 16–17 mm; specimens. hind wing length 15–16 mm. Scanning electron micrographs were made by the Colour (Fig. 2). Head. Labium beige; labrum green- second author using a Philips XL30 scanning elec- ish-blue; anteclypeus black; postclypeus bright blue

Downloaded from Brill.com10/07/2021 11:49:16AM via free access Englund & Polhemus: Zygoptera of the Austral Islands (Odonata) 27 on lower section, upper portion black with metallic length 18 mm; hind wing length 17 mm. blue overtones; genae greenish-blue, mandible dark Colour. Coloration duller than in male, present- brown with apices of teeth black, frons transversely ing an overall dull blue greenish appearance. Post- greenish-yellow; eyes bichromatic, black dorsally ocular spots smaller, green; eyes greenish-yellow; grading to bluish-green to green ventrally; vertex mesepisternum with slender, green mid-dorsal stripe; black, sparsely covered with long thin brown setae, abdomen black dorsally, yellowish-green ventrally. ocelli gold; post ocular spots large, ovate, bright blue. Structural characters. Thorax: Pronotum with pos- Thorax. Prothorax with anterior lobe of pronotum terior lobe laterally explanate, posterior margin bright blue, middle and posterior lobes of pronotum broadly convex, not highly modified, general col- black, ventral edge of propleuron lined with blue. oration black with scattered small, light greenish- Pterothorax with anterior margin of mesostigmal yellow markings adjacent to anterior terminus of plate raised, pale blue; mesepisternum predomi- antehumeral stripe. Mesostigmal lamellae narrow, nantly black, with a pair (1+1) of prominent bright transversely oriented, posterior margins slightly blue antehumeral stripes, these stripes extending raised and laterally swollen, these expanded portions the entire length of the mesepisternum; mesopleu- of posterolateral margin pale blue, nearly confluent ral suture covered by broad black stripe extending with anterior terminus of antehumeral stripe, cen- entire length of the suture; mesepimeron and mete- tral depression between lamellae small, triangular in pisternum bright pale blue, with a short, black, shape (Fig. 26). Remainder of pterothorax mostly roughly triangular mark covering visible part of black, with pale blue antehumeral stripes extending interpleural suture, creating a V-shaped margin to along entire length. the blue coloration posteriorly; metapleural suture Abdomen: Segment VIII bearing a short, brown, covered by narrow, irregular black stripe, this pointed vulvar spine (Fig. 29). stripe becoming progressively broader posteriorly; Immature. (n = 1, found in association with adults in upper two thirds of mesepimeron bright blue with swiftly flowing stream habitat). a blue V-shaped notch at the posterior end of the Colour. Overall color brownish-green dorsally, ven- mesepimeron; metepimeron pale blue, trending trally more brown than green; with asperities on dor- toward tan along ventral margin; meso- and meta- sal surface darker brown. coxae pale blue; entire thorax covered with fine, light Structural characters. Body strongly laterally com- brown setae. pressed and streamlined (Fig. 15). Dorsal surface Structural characters. Wings. Shape and venation as with rough, bumpy appearance; head wider than in Fig. 8. thorax or abdomen; with narrow, robust, caudal Abdomen. Posterior margin of segment X bearing a laminate gills bearing long, white, filamentous tips small bilobate process medially, these processes pro- on posterior ends; gill margins bearing fine black- jecting slightly upward in lateral view (Figs 5, 11, 12). ish brown serrations, set with long, fine, pale setae, Male secondary genitalia: Penis with an obvious, tri- strongly raised serrations also present on axial tra- angular zone of articulation separating the basal and cheae of gills; premental setae inconspicuous, with terminal segments; posterior margin of basal seg- only one visible; papal lobes lacking setae. ment bearing a set of stout, spinose setae; terminal segment bearing a subapical tubercle, this tubercle Etymology bearing only tiny, incipient spinose processes; apex The name “rurutana” refers to the island of Rurutu, of terminal segment bifurcate, bearing a pair of curv- to which this species is endemic. ing, acuminate processes (Fig. 32). Male appendages: Cercus moderately large, shorter Distribution than paraproct when viewed laterally (Fig. 5), Endemic to the island of Rurutu in the Austral upper margin terminating in acute point, lower sec- Islands. tion forming a downward curving blade, this ven- tral blade with posterior margin broadly curved in Comparative notes oblique view, inner anterior margin straight, apex In comparison to other endemic Zygoptera from the acute (Figs 12, 13). Paraproct with basal section Austral Islands, I. rurutana is a smaller, more deli- stout, posterior half narrowed and tapering to a blunt cate, and lighter-colored species, and can be easily point when viewed laterally (Fig. 5), apex forming a separated by the structure of the male abdominal small, inwardly curving point when viewed dorsally terminalia (compare Figs 5, 11, 12 with Figs 6–7, (Fig. 11). 17–19, 21–22). The male caudal appendages, partic- Female. Size (n = 1). Total length 28 mm (includ- ularly the cerci, are similar in general form to those ing ovipositor); abdomen length 22 mm; fore wing of I. thelmae from Rapa (Figs 7, 21), but greatly

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Figs 2–4. Endemic Ischnura species from the Austral Islands, color photographs of males. – 2. I. rurutana from Rurutu. 3. I. jeany- vesmeyeri from Raivavae. 4. I. thelmae from Rapa.

2

3

4

reduced in size compared to either that species or segment, but lacks the long spinose processes on I. jeanyvesmeyeri from Raivavae (Figs 6, 17–19). the subapical tubercles seen in R. thelmae and many In lateral view, the paraprocts are quite small and other Polynesian Ischnura species (compare Figs 32, stubby, and the cerci much reduced and more 33). Females of I. rurutana have mesostigmal lamel- pointed than in I. jeanyvesmeyeri (compare Figs 5, 6). lae that are laterally expanded, rather than being of The penis of the male secondary genitalia is similar even width throughout as in R. thelmae, or possessing in basic form to that of I. thelmae from Rapa, pos- circular depressions as in R. jeanyvesmeyeri (compare sessing clearly defined basal and terminal segments, Figs 26–28). The vulvar spine on female abdomi- a subapical tubercle on the terminal segment, and nal segment VIII is present, but very small in paired acuminate processes apically on the terminal I. rurutana, whereas in both R. thelmae and

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R. jeanyvesmeyeri it is represented as a more massive, angulate ventral projection (compare Figs 29–31). Based on the single larva at hand, the gills of I. ruru- tana, although lamellate as is typical of Ischnura as a whole, are shorter and more laterally compressed in comparison to the widespread Ischnura aurora (Lief- tinck 1959), which has longer and more slender gill filaments. A trend toward shortened and compressed gills is characteristic of the larvae of Ischnura species living in swiftly flowing waters (Lieftinck 1959). Larvae were not collected for the other Austral Island species, thus no further comparisons can be made in regard to the regional fauna. In terms of coloration, I. rurutana has a more bluish- 100 μm yellow overall coloration than I. jeanyvesmeyeri 5 (compare Figs 2, 3), with some individuals of I. rurutana having an almost greenish-yellow tinge on the ventral surface of the abdomen that is quite striking in comparison to the darker black dorsal abdomen and lighter colored legs seen in I. jeany- vesmeyeri. The terminal abdominal tergites are also much more extensively marked with blue than in I. thelmae (compare Figs 2, 4).

Biological notes Ischnura rurutana has to date been taken only along Puputa Stream, upslope of the village of Moerai in the northeastern sector of Rurutu. This species occurred along a reach extending upstream from several large water tanks at the main diversion for the Moerai town water supply to a tall cascade 100 μm (Fig. 14); this entire reach was shaded by a closed 6 canopy of Hibiscus tiliaceus except for the area in the immediate vicinity of the waterfall. Because of this riparian canopy, lighting was dappled on and around the stream, and the damselflies were consequently difficult to observe. Once individuals were sighted and approached they generally flew straight up and disappeared into the overarching canopy, mak- ing collections difficult. One female was observed ovipositing on a 2 m sloping cascade in the forest adjacent to the larger, unshaded cascade on the main stream channel. Males were mostly collected along the main stream corridor as they flew beats above stream riffles. Several individuals were also collected at midday in a shaded area at the base of the cascade. This species therefore seems to prefer shaded areas along higher gradient reaches. Four larvae were col- 100 μm lected by benthic kick sampling in the fastest parts 7 of riffles along the main channel, immediately below Figs 5–7. Endemic Ischnura species from the Austral the large cascade. This preference for breeding sites Islands, left lateral views of male abdominal terminalia. in fast flowing waters stands in marked contrast – 5. I. rurutana from Rurutu. 6. I. jeanyvesmeyeri from to many other Ischnura, including the widespread Raivavae. 7. I. thelmae from Rapa. I. aurora, that breed in stream pools or standing water habitats.

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Figs 8–10. Endemic Ischnu- ra species from the Austral Islands, male fore and hind wings. – 8. I. rurutana from Rurutu. 9. I. jeanyvesmeyeri from Raivavae. 10. I. thelmae from Rapa.

8

9

10

Ischnura jeanyvesmeyeri sp. n. (BPBM); 2 ?, Vaipa Stream, above water diver- Figs 3, 6, 9, 17–19, 24, 27, 30, 33 sion and upstream of dense Hibiscus growth, 207 Type material. Holotype ?, French Polynesia, m, 23.86222°S, 147.64679°W, 25 November Austral Islands, Raivavae, Vaipa Stream, 122– 2002, R.A. Englund (BPBM); 1 ?, Tuarani River 220 m, 23.86333°S, W 147.64676°W, 29.xi.2002, at 1st road crossing (cement bridge), 20.xi.2002, BPBM-FP 1498, R.A. Englund (BPBM). Para- 23.86903°S, 147.65465°W, flying midstream, types: French Polynesia, Austral Islands, Raivavae: R.A. Englund (BPBM); 1 ?, 2 /, stream, below same data as holotype, 2? 1/ (BPBM); 1?, small bridge crossing at taro fields between Mahana- wooded stream below Mt. Hiro, 170 m, 23.86100°S, toa and Rairua, December 2002, 23.87065°S, 147.65059°W, 23.xi.2002, R.A. Englund 147.67918°W, R.A. Englund (BPBM); 1 / (teneral),

Downloaded from Brill.com10/07/2021 11:49:16AM via free access Englund & Polhemus: Zygoptera of the Austral Islands (Odonata) 31 spring/taro patch below summit of Mt. Hiro, 265 m, 22 November 2002, 23.85602°S, 147.65671°W, R.A. Englund (BPBM); 2 ? , Vaipa Stream, cas- cade face, 120–215 m, 29.xi.2002, 23.86333°S, 147.64676°W, R.A. Englund (BPBM); 1 ? , Vaipa Stream, cascade, 210 m, 25.xi.2002, 23.86222°S, 147.64679°W, R.A. Englund (BPBM).

Description Male. Size. Dimensions of holotype: Total length 42 mm; abdomen length 39 mm; fore wing length 22 mm; hind wing length 21 mm. Intraspecific vari- ation: total length 41–43 mm (n = 10); abdomen length 33–36 mm (n = 10); fore wing length 23–23 mm (n = 4); hind wing length 21–23 mm (n = 9). Colour (Figs 3, 16). Head. Vertex black with slight tinge of green, postocular spots large, ovate, bright 11 100 μm medium blue; eyes bichromatic, ventral portion of eyes greenish-yellow, this coloration trending from bright green dorsally to yellow adjoining black dor- sal portion of eye; ocelli gold; frons transversely pale aqua; postclypeus with upper half black, lower half sapphire blue; anteclypeus black; labrum pale aqua, genae greenish yellow, mandible dark brown, with apices of two stout teeth dark brown, Thorax. Dorsal coloration predominantly black, with 2 short, narrow, bright blue mid-dorsal stripes extending less than 1/5 the length of the pterotho- rax, lateral ptrerothorax with broad bright sky blue stripes. Pronotum black, anterior lobe narrowly bright sky blue anteromedially; propleuron with small blue spot along ventral margin. Mesepister- num black, bearing scattered slender, erect pale setae, two (1+1) narrow blue antehumeral stripes present dorsally on anterior portion, these stripes extending 12 100 μm posteriorly for only 1/5 the length of the mesepis- ternum, humeral stripe broad, black, confluent with black coloration on lower portion of mesepisternum, this combined dark area broadly covering meso- pleural suture; mesepisternum broadly sky blue; metapleural suture covered by an irregular longitu- dinal dark stripe of moderate width; metepimeron broadly bright sky blue, anterior 1/5 black; ventral surface of pterothorax blackish brown. Legs. Femora and tibiae black dorsally, ventral por- tion of femora light bluish-cream color, ventral por- tions of tibiae entirely black, tarsi embrowned; fem- oral and tibial spines long and stout, black, length approximately 3 times width of corresponding leg 100 μm segment; tarsal spines black, shorter, length equal to 13 thickness of corresponding tarsal segment; claws very gently curved, nearly straight, tips apically bidentate, Figs 11–13. Ischnura rurutana from Rurutu, details of coloration amber brown, apices black. male abdominal terminalia. 11. Terminal abdomen, Wings. General coloration pale fumate, pterostigma dorsal view. 12. Terminal abdomen, posterior view. dark brown, narrowly margined with pale tan (Fig. 9). 13. Left cercus and paraproct, inner lateral view.

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midline stripe; segments IX and X broadly blue dorsally, this blue coloration extending downward roughly half the distance to the ventral margins of these segments. Structural characters. Wings: Shape and venation as in Fig. 9. Male secondary genitalia: Penis lacking an obvious zone of articulation demarcating the basal and ter- minal segments, incipient zone of demarcation indi- cated only by a vertical set of relatively short, spinose setae; terminal segment lacking a subapical tubercle and associated spinose processes; apex of terminal segment bifurcate, massive, bearing a pair (1+1) of expanded bilobate processes separated by a deep con- cavity, and resembling a grasping hand in lateral view (Fig. 33). Male appendages. Cercus large, stout, strongly pro- jecting posteriorly in lateral view (Fig. 6), apices rounded in lateral view, pointed and weakly hooked inward in dorsal view (Figs 6, 17–19), inner basal margin with prominent ventrally directed process, this process elongate and triangular in posterior view (Fig. 17). Paraproct short, rounded, weakly projecting posteriorly in lateral view (Fig. 6); api- 14 ces expanded, bulbous, central section constricted, basal section enlarged, stout, dorsally concave (Figs 17–19). Female. Size (n = 1). Total length (including ovi- positor) 39 mm; abdomen length 31 mm; fore wing length 25 mm; hind wing length 24 mm. Colour: Overall color pattern quite similar to males except slightly lighter in overall color saturation; mid-dorsal stripe extending along entire length of pterothorax, coloration light greenish-blue, broad stripes on lateral pterothorax light powder blue. Structural characters. Thorax. Pronotum predomi- nantly black, bi-tumescent centrally, these tumes- ences black with small blue spots in their centers, 15 separated by a shallow longitudinal median sul- Figs 14–15. Ischnura rurutana from Rurutu, breeding cus, posterior pronotal margin with a prominent, habitat and immature stage. 14. Type locality at Puputa V-shaped incision medially, the apex of this incision Stream, above Moerai on northeastern Rurutu. 15. Im- directed anterad, widened posterior section pale mature, lateral view, photograph of living specimen. blue, separating a pair (1+1) of narrow, explanate, crescent-shaped lobes, these lobes black with extreme lateral apices pale blue. Mesostigmal lamel- Abdomen. Dorsal coloration predominantly black, lae expanded and excavate laterally, forming a pair brown ventrally, covered with fine pale setae; seg- (1+1) of ear-shaped structures with strongly raised ment I with large bright blue spot laterally on each margins to either side of a prominent, transversely side; segment II with small cream colored spot ante- ovate medial depression, centers of the ear-shaped rolaterally and irregular pale blue spot posterolater- depressions pale blue, remainder of lamellae black ally on each side; apical annulus between segments (see Fig. 27). Remainder of pterothorax, exclusive of VII and VIII blue dorsally; lateral portions of seg- lamellae, mostly black, with pale blue antehumeral ment VIII bearing a pair (1+1) of vertically oriented stripes extending along entire length. ovate blue patches, these patches extending dorsally Abdomen. Segment VIII acutely angulate, but not but not meeting at midline, leaving narrow black produced into a vulvar spine (Fig. 30).

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Fig. 16. Ischnura jeanyvesmeyeri from Raivavae, dorsal habitus (S. Meyers illustration).

Etymology antehumeral stripes seen in the latter species (com- This species is named for Jean-Yves Meyer in honor pare Figs 23, 24). While similar in size to I. thelmae of his spirit of adventurous fieldwork, and his out- from Rapa, males of I. jeanyvesmeyeri have a much standing personal dedication to the conservation of darker dorsal and ventral thorax and abdomen French Polynesia’s native fauna and flora. (compare Figs 3 and 4, 24 and 25); in particular, I. thelmae has a more greenish-yellow tinge overall; Distribution has a pterothorax with antehumeral stripes extend- Endemic to the island of Raivavae in the Austral ing along its entire length; and possesses blue dorso- Islands. apical stripes on the last three abdominal segments (Fig. 4). Females of I. jeanyvesmeyeri have coloration Comparative notes similar to the males, but with the blue areas of the Ischnura jeanyvesmeyeri is a strikingly large species, thorax and the ventral areas of the abdomen slightly the males of which are easily distinguished from the lighter overall; this contrasts with I. rurutana and two other endemic Ischnura species found in the I. thelmae, where males and females exhibit strong Austral Islands by the structure of the abdominal ter- intersexual color dimorphism. minalia (compare Figs 6, 17–19), the male second- Distinctive character states for I. jeanyvesmeyeri in ary genitalia (Fig. 33), and the female mesostigmal the context of the Austral Islands biota include the lamallae (Fig. 27). In addition, I. jeanyvesmeyeri is highly enlarged male cercus on the terminal abdo- much larger and more heavy-bodied than I. ruru- men (Fig. 6); the highly expanded apical processes tana from Rurutu, and also lacks the full length of the terminal segment of the male secondary

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genitalia, which in lateral view resemble a grasping hand (Fig. 33); the absence of a vulvar spine on the venter of the female abdomen (Fig. 30); and the female mesostigmal lamellae bearing roughly ovate, pale colored depressions (Fig. 27). These character states are dissimilar to those seen in other Coenagrio- nidae occurring in the Austral Islands, or even in the Society and Marquesas archipelagos, demonstrating that I. jeanyvesmeyeri is an isolated and anomalous taxon in the context of the overall French Polynesian Zygoptera biota.

Biological Notes 100 μm Virtually all the streams on the island of Raivavae are 17 at some point diverted for agricultural or domestic uses, and most are quite small (< 1 m wide, and only 3–15 cm deep in most cases), occupying short catch- ments running steeply off the central ridgeline of this small, elongate island. Within such habitats, I. jeany- vesmeyeri was collected at a wide range of elevations, from just above sea level at two locations (at 6 m elevation on the Tuarani River and at 1 m elevation on an unnamed stream between Mahanatoa and Rai- rua) upward to 265 m on the upper Vaipa Stream. One female was collected at the highest elevation where water was observed on Raivavae, around a small taro patch and spring area at 265 m. Both of the lower elevation locations at which this species was taken were heavily vegetated areas lying between 100 μm taro fields. Specimens were found only along shaded 18 stream reaches, and no individuals were observed in or around the large adjoining lowland taro fields where I. aurora occurred instead. Along low eleva- tion stream reaches I. jeanyvesmeyeri was most often found in proximity to exposed root mats trailing in the stream along the main stream channel. Although females were observed ovipositing in such root mats, attempts to collect larvae from the mats were unsuc- cessful. At higher elevation, another female was observed ovipositing on algae mats at a cascade along Vaipa Stream. The most productive collection locality for this spe- cies was along upper Vaipa Stream above the diver- sions, where a series of cascades provided high quality 100 μm habitat. The stream at this point was lined with thick 19 growths of Dicranopteris linearis ferns, and in com- Figs 17–19. Ischnura jeanyvesmeyeri from Raivavae, mon with most Raivavae streams the bed substrate details of male abdominal terminalia. 17. Terminal ab- consisted of bare rock with little loose rock or gravel, domen, dorsal view. 18. Terminal abdomen, posterola- but abundant root mats and aquatic algae. Very few teral view. 19. Left cercus and paraproct, inner posterior other aquatic organisms were collected at this site, view. despite extensive dipnet sampling. By contrast, males of I. jeanyvesmeyeri were easily collected here as they flew beats along the main stream corridor.

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Ischnura thelmae Lieftinck, 1966 Figs 4, 7, 10, 20–22, 25, 28, 31, 34 Ischnura thelmae Lieftinck, 1966: 92. Holotype ?: Rapa, Maii Bay.

Description Male. Size (n = 1). Total length 43 mm; abdomen length 34 mm; fore wing length 22 mm; hind wing length mm. Colour (Fig. 4). Head. Ocelli gold, vertex black, head overall lightly covered with long thin brown setae; labium buff; bottom 2/3 of labrum yellowish- green, thickly covered with brown setae, upper por- tion of labrum brown; anteclypeus bright yellow, postclypeus black with fine brown setae overhanging anteclypeus; eyes bichromatic, yellow ventrally, black dorsally; frons transversely yellow; post ocular spots large, ovate, bright blue, vertex black. Fig. 20. Ischnura thelmae from Rapa, photograph of Thorax. Anterior lobe of pronotum bright yellow, female “green form”. middle lobe black, posterior lobe with bright yellow spot laterally, above this an anterior brown spot bear- ing long, light brown setae; mesostigmal plate bright yellow, raised along anterior margin. Pterothorax 100 μm covered by fine pale setae, bearing two bright yellow antehumeral stripes extending along entire length; mesopleural suture black; mesepimeron with small black notch at posterior end; metapleural suture black; metepimeron light blue by base of hindwing but trending yellow ventrally toward metinfraepister- num; entire thorax covered with fine, pale setae. Legs. Femora black dorsally, yellow ventrally, bearing stout black spines, length of these spines less than twice width of corresponding femur; tibiae mottled light brown, spotted with black dorsally, yellow ven- trally, bearing long, black, angled spines, length of these spines greater than twice width of correspond- 21 ing tibia; tarsi brown with black annuli at apices of each segment, bearing short, black spines, length of these spines equal to thickness of corresponding tarsal segment; claws very gently curved, nearly straight, tips apically bidentate, coloration amber brown, apices black. Wings. General coloration very pale fumate; pter- ostigma on forewing dark brown with posterior end much lighter, vein ringing pterostigma dark brown; pterostigma on hindwing a slightly lighter, more uni- form brown than on forewing (Fig. 10). Abdomen. Dorsal coloration predominantly dark brown, each apical annulus light yellowish-brown, this same coloration extending laterally and ventrally; segment I black dorsally, bright yellow laterally, yel- 22 100 μm low area covered by fine white pruinosity, first apical annulus bright blue; segments II–VI black dorsally, Figs 21–22. Ischnura thelmae from Rapa, details of dark yellow ventrally; segments VII–X black dorsally male terminalia. 21. Paraproct, inner lateral view. and laterally, segments VII–IX bearing bright blue 22. Paraproct, dorsal view.

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Male secondary genitalia: Penis with an obvious, triangular zone of articulation separating the basal and terminal segments; posterior margin of posterior segment bearing a set of stout, spinose setae; termi- nal segment bearing a subapical tubercle, this tuber- cle bearing moderately long, gently curving spinose processes; apex of terminal segment bifurcate, bear- ing a pair of curving, acuminate processes (Fig. 34). Male abdominal appendages. Cercus of moderate length, not exceeding apex of paraproct when viewed laterally (Fig. 7), curving downward posteriorly, apex broadly rounded in lateral and dorsal views, in 23 oblique view appearing as a large semi-circular blade with a sharply pointed apex (Fig. 21). Paraproct longer than cercus, stout basally, posterior half slen- der and tapering to an acute, upwardly curving point when viewed laterally (Fig. 7); broadly curving and progressively tapering to an acute, incurved, slightly cupped apex when viewed dorsally (Fig. 22). Female. Size (n = 3). Total length (including oviposi- tor) 37–40 mm; abdomen length 27–31 mm; fore wing length 22–23 mm; hind wing length 22 mm. Colour. This species has heterochromatic females with two color forms: an “orange form” with bright orange coloration on the thorax and abdomen, and a “green form” with a dull, forest green appearance (Fig. 20). 24 Structural characters. Thorax. Pronotum predomi- nantly orange, bi-tumescent centrally, separated by a broad, shallow, roughly triangular median sulcus, posterior portion of this sulcus black; posterior pro- notal margin not strongly modified, nearly straight, sharply raised to form a narrow lip. Mesostigmal lamellae orange, expanded laterally to form small, roughly rectangular plates, anterior and posterior margins of these plates narrowly raised, medial depression between these plates black, transversely ovate with triangular central sulcus, this sulcus roughly triangular in shape with apex directed pos- teriorly (Fig. 28). Remainder of pterothorax mostly orange, with broad black middorsal stripe flanked 25 to either side by much narrower black antehumeral Figs 23–25. Endemic Ischnura species from the Austral stripes, all these stripes extending along entire length Islands, lateral view of male pterothorax. 23. I. ruru- of pterothorax. tana from Rurutu. 24. I. jeanyvesmeyeri from Raivavae. Abdomen. Segment VIII bearing a large, acute, 25. I. thelmae from Rapa. brown ventral apical spine (Fig. 31).

Distribution dorso-apical stripes; segment X with posterior mar- Endemic to the island of Rapa (also known as Rapa gin bearing prominent medial process (Fig. 7), this Iti) in the Austral Islands. process bilobate when viewed dorsally (Fig. 21), pro- jecting strongly backward and slightly upward when Material examined. French Polynesia, Austral Islands, viewed laterally (Fig. 7). Rapa: 1 ? (genitalia used for SEM), Hiri Bay side of Structural characters. Wings: Shape and venation as Mt. Morogouta, below ridge trail, mixed Metrosideros/Psid- in Fig. 10. ium/Freycinetia forest, 238 m, 27.62356°S, 144.34457°W,

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26 27 28 Figs 26–28. Endemic Ischnura species from the Austral Islands, dorsal views of female head and pterothorax. 26. I. rurutana from Rurutu. 27. I. jeanyvesmeyeri from Raivavae. 28. I. thelmae from Rapa.

16.xii.2002, R.A. Englund (BPBM); 1 /, stream from description of the living coloration of this species, Hiri Bay side of Mt. Morogouta, below ridge trail, small along with some brief ecological notes. forested streamlet in mixed Metrosideros/Freycinetia/ Despite its larger size, I. thelmae shares many aspects Psidium forest, 190 m, 27.62358°S, 144.34572°W, I. rurutana 16.xii.2002, R.A. Englund (BPBM); 1 ?, 1 /, forested of its overall morphology with from stream above Haurei Town water tanks, 61 m, 27.62401°S, Rurutu, including the general form of the termi- 144.33551°W, 15.xii.2002, , R.A. Englund (BPBM); nal abdominal appendages (compare Figs 5, 13 1 /, along trail at ridgetop in mixed Weinmannia/Eurya/ to Figs 7, 21), male secondary genitalia (compare Melicope/Corokia/Pittosporum forest, 305 m, 9.xii.2002, Figs 32, 34), antehumeral stripes that extend the R.A. Englund (BPBM). entire length of the dorsal pterothorax in males (com- pare Figs 23, 25), and some degree of development Comparative notes of a vulvar spine on the ventral abdomen of females This species was described by Lieftinck (1966) on (compare Figs 29, 31). The male secondary genita- the basis of 10 individuals collected in 1963 by lia are similar in many respects to those of I. cardi- Dr. Gates Clarke and his wife Thelma M. Clarke, for nalis Selys from the western , indicat- whom the species was named. It can be easily rec- ing these taxa may be elements of a common line- ognized among the suite of Austral Island endemic age. Males and females of I. thelmae exhibit strong Ischnura by its geographic provenance; distinctive intersexual color dimorphism, as in I. rurutana, but male abdominal appendages (compare Figs 7, 21, in addition there is intrasexual color polymorphism 22); male secondary genitalia with long spinose pro- among the females of I. thelmae. Two female color jections arising from a subapical tubercle on the ter- morphs occur, a “green form” and an “orange form.” minal segment (Fig. 34); and the presence of a stout, Females of the “orange form” also have a noticeably angulate vulvar spine on the female ventral abdomen lighter brown pterostigma. (Fig. 31). Lieftinck found this species remarkable because at Biological notes the time it was the largest Ischnura species known in Lieftinck (1966) noted that collections of this spe- the world, although as noted previously, our newly cies by Gates Clarke were taken from high eleva- described I. jeanyvesmeyeri from Raivavae is of simi- tions above 300 m, and that Clarke believed that lar size. The specimens examined by Lieftinck were the immature of this species would be found in the badly faded and had lost most of their original col- leaf axils of the climbing pandanus, Freycinetia arbo- oration. We have therefore provided a supplemental rea, which was abundant in the 1960s on the steep

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Freycinetia, and often found with only modest effort. In addition, if I. thelmae was a leaf axil breeder then adult damselflies would have been expected to be common in the area containing the last great stands of Freycinetia near the summit of Mt. Perhau. But in fact, no Ischnura thelmae were observed by a team of six biologists during two full days spent in pris- tine cloud forest habitat near the Mt. Perhau sum- mit, despite excellent weather conditions. Instead, 29 all specimens were taken at lower elevations along streams. In our view, it is more likely that this species is a stream breeder, but with adults that forage at con- siderable distances away from streams. For example, one collection site was behind the main Rapa village of Haurei, upstream of the large municipal water tank area. The single male damselfly observed here along the guava-lined stream took off into the for- est after being disturbed, whereas typical damselfly behavior on the island of Raivavae would be for the 30 individual to return to the stream. Similar behavior was also observed among I. thelmae females as well. In addition, the collection of three out of the four females in association with streams during field work on Rapa suggests lotic oviposition sites. Ultimately more benthic sampling in Rapa streams, which was not undertaken due to time constraints, will be nec- essary to determine the breeding site of I. thelmae. Although common in the 1960s (Lieftinck 1966), I. thelmae now appears to be seriously threatened not by introduced alien fish species, such as has occurred in Hawaii (Englund 1999), but instead by loss of 31 riparian forest. On the basis of our observations, the Figs 29–31. Endemic Ischnura species from the Austral adults are closely associated with riparian forests, Islands, right lateral view of female terminal abdomen. and were never observed during thorough surveys in 29. I. rurutana from Rurutu. 30. I. jeanyvesmeyeri from open riparian habitats, including overgrazed stream Raivavae. 31. I. thelmae from Rapa. and pasture areas (Englund 2003). Our observa- tions also indicate that adults of I. thelmae forage far from streams in areas of native forest. There is thus a potential link between the condition of the native hillsides of Rapa. However, due to grazing and tram- forest and the health of these native damselfly popu- pling of cattle, which have steadily worked their way lations. up into the island’s highest areas, such as Mt. Perahu, Most of the native terrestrial insect biodiversity Freycinetia is now much less abundant on Rapa than remaining on Rapa is now found in a narrow zone in the past. of native forest between 500–650 m at the summit In addition, extensive observations made by the first of Mt. Perau that is estimated to be no more than author during field work on Rapa indicate that is 20 ha in size (Englund 2003, J.Y. Meyer, pers. highly unlikely that I. thelmae is a terrestrial leaf axil comm). The collection of many undescribed insect breeder, as speculated in Lieftinck (1966). First, at species from Mt. Perau in December 2002 by Eng- least a hundred separate Freycinetia axils were exam- lund (2003) illustrates that much remains to be ined for larvae at the summit of Mt. Perhau, and no discovered about the fauna from this mostly intact larvae were found. Although such absence does not native forest area. The cattle grazing line near the conclusively refute the leaf axil breeding hypoth- summit of Mt. Perau starts at about 370–400 m esis, we do note that in the Hawaiian Islands, leaf elevation, and cattle were visibly trampling down axil breeding damselflies are commonly collected in Freycinetia to gain further access to the uppermost

Downloaded from Brill.com10/07/2021 11:49:16AM via free access Englund & Polhemus: Zygoptera of the Austral Islands (Odonata) 39 summit areas, with evidence of goats also found near the very summit. In 2002, goat damage was observed as high as the 550 m elevation on the Mt. Perau ridgelines. We believe that this progressive loss of native forest ecosystems on Rapa represents a contin- uing threat to the long term persistence of I. thelmae. 32 Ischnura aurora aurora Brauer Ischnura aurora aurora Brauer, 1865: 510. Holotype from Tahiti.

Distributional notes This species ranges broadly throughout the Indo- Pacific region, from India and Sri Lanka eastward through Southeast Asia to New Zealand and Micro- nesia, and is also widespread across the archipelagos of French Polynesia. In the Austral Islands, I. aurora 33 was common in lowland palustrine and lotic ripar- ian habitats on all islands sampled. On Tubuai and Rimatara this was the only Ischnura species taken, while on Rapa, Raivavae, and Rurutu it was collected in addition to the locally endemic species that occur in the uplands of these islands. The recent Austral Island records for I. aurora will be summarized in a forthcoming publication. 34 Ecological notes Figs 32–34. Endemic Ischnura species from the Austral In contrast to the endemic Austral Island damselflies, Islands, right lateral view of male secondary genitalia. which were never encountered in or around lowland 32. I. rurutana from Rurutu. 33. I. jeanyvesmeyeri from taro fields or open wetland areas, Ischnura aurora was Raivavae. 34. I. thelmae from Rapa. abundant in such habitats.

male secondary genitalia; and some degree of Discussion development of a vulvar spine in females. These char- The current assignment of all the endemic Austral acter states are, by contrast, not present in I. jeanyves- Islands damselflies to the genus Ischnura is done pro- meyeri from Raivavae. Finally, I. rurutana and visionally, and in recognition of the fact that certain I. thelmae exhibit intersexual color dimorphism, species do not conform to the strict definition of this which is apparently lacking in I. jeanyvesmeyeri. genus. For instance, Westfall & May (1996) consid- These character state incongruities, coupled with the ered the presence of a dorsoapical prominence on lack of a vulvar spine in I. jeanyvesmeyeri, imply that abdominal tergite X to be a key characteristic for the the Austral Island damselfly species currently held as genus Ischnura, at least for the North American taxa a whole in Ischnura may be the result of two separate they treated. Such a structure is present in I. aurora, colonizations, with I. jeanyvesmeyeri representing a I. rurutana, and I. thelmae, but absent in I. jeany- separate lineage, a hypothesis that should be further vesmeyeri (compare Figs 5–8), thus the latter species evaluated based on molecular characters before for- would not key to Ischnura in Westfall & May (1996). mal taxonomic changes are proposed. In addition, both I. rurutana from Rurutu and The question of where the putative Ischnura species I. thelmae from Rapa share several putatively homol- endemic to the Austral Islands lie phylogenetically in ogous character states, notably the curving, blade- relation to other endemic radiations of superficially like extension of the ventral portion of the terminal similar stocks in the Society and Marquesas archi- cercus in males; the presence of a bilobate medial pelagos is still unresolved. The general male genitalic process on the posterior margin of male abdo- layout of the endemic species on Rurutu and Rapa minal segment X; a subapical tubercle and acuminate is similar to that of Tahitian species also currently apical processes on the terminal segment of the held in Ischnura, and Marquesan species held in the

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locally endemic genus Bedfordia (Mumford 1942). Clouard, V. & A. Bonneville, 2005. Ages of seamounts, It is worth considering that isotopic dating indi- islands, and plateaus of the Pacific Plate. – In: cates the Austral Islands as a whole are of consider- G.R. Foulger, J.H. Natland, D.C. Presnall, & ably greater age than either the Society or Marquesas D.L. Anderson (eds.), Plates, Plumes and Paradigms, groups (Clouard & Bonneville 2001), and that the Geological Society of America Special Paper 388: endemic damselflies of the Australs may thus be rem- 71–90. nant representatives of the stocks that initially colo- Englund, R.A. 1999. The impacts of introduced poeciliid fish and Odonata on endemic Megalagrion (Odonata) nized what is now French Polynesia, and potentially damselflies on Oahu Island, Hawaii. – Journal of In- gave rise to the subsequent radiations that arose on sect Conservation 3: 225–243. islands to the north and east. Englund, R.A. 2003. Report for the 2002 Pacific Biological Survey, Bishop Museum Austral Islands Expedition to Raivavae and . – Prepared for the Délegation Acknowledgments à la Recherche (Ministère de al Culture, de l’Enseigne- The authors offer special thanks to J.Y. Meyer and to ment Supérieur et de la Recherche), Papeete, Tahiti, the Délégation à la Recherche (Ministère de la Pro- Polynésie française. v + 30 pp. Lieftinck, M.A. 1959. On the New Guinea species of motion des Ressources Naturelles, Gouvernement Ischnura charpentier and Oreagrion ris. – Nova Guinea de la Polynésie française), Papeete for funding field 10 (2): 213–240. collections by the first author during two trips to Lieftinck, M.A., 1966. Some Odonata of Rapa Island, the Austral Islands. The first author would also with descriptions of three Polynesian species of Ischnu- like to extend his gratitude to the other members ra Charpentier. – Tijdschrift voor Entomologie 109: of these field expeditions for their assistance in col- 89–102. lections, photography, and general fieldwork: Jean- Mumford, E.P., 1942. A new genus Bedfordia, and other François Butaud, Benoît Fontaine, Olivier Gargo- records of dragonflies from the . miny, Jacques Florence, Claude Thibault, Rosemary – Annals and Magazine of Natural History (11)9: Gillespie and Diana Percy. We also thank Brad Evans 824–837. of the Bishop Museum for preparing the Austral Polhemus, J.T. & D.A. Polhemus, 2008. A new genus of Islands base map. Microveliinae from the Austral Islands, French Polynesia The second author wishes to express his gratitude (Heteroptera, Veliidae). – In: S. Grozneva & N. Simov to Scott D. Whittaker of the Smithsonian Institu- (Eds.), Advances in Heteroptera Research. Festschrift in Honor of the 80th Anniversary of Michail Josifov: tion’s Laboratories of Analytical Biology, National 293–302. Pensoft Publishers, Sofia-Moscow. Museum of Natural History, Washington, DC for Westfall, M.J., Jr. and M.L. May. 1996. Damselflies of assistance with the scanning electron microscopy North America. – Scientific Publishers, Gainesville. and to Elin Claridge for logistical assistance during a x + 650 p. visit to the Austral Islands in 2007. This research was supported by grant DEB-0451971 from the U. S. National Science Foundation, Wash- ington, DC, and represents Contribution 2010–007 to the Pacific Biological Survey, Bishop Museum.

References Brauer, F., 1865. Dritter Bericht über die auf der Weltfahrt der kais. Fregatte Novara gesammelten Libellulinen. – Verhandlungen der Zoologische-Botanischen Gesell- Received: 8 February 2009 schaft in Wien 15: 501–512. Revised version accepted: 25 January 2010

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