Indolestes anomalus Fraser, 1946

Kosterin, Oleg E., Garrison, Rosser, Kompier, Tom & Farrell, Dennis, 2019, Taxonomic notes on Indolestes Fraser, 1922 (Lestidae, Zygoptera). 3. Male and clarified type locality of Indolestes anomalus Fraser, 1946, Zootaxa 4555 (1), pp. 67-78 : 68-78

Indolestes anomalus Fraser, 1946

Figs. 1–7

Indolestes anomala Fraser 1946: 43 –44, figs. 1c, 2e—original description of “a single rather teneral female” from “ Siam: Doun-moi”, drawings of the pterostigma and thorax in lateral view; Hämäläinen & Pinratana 1999: 32 —report for Tak (June) [Mae Sot, 1 vi 1986, 1 ♂, 1 ♀, A. Pinratana’s collectors leg.—M. Hämäläinen, pers. comm.], Lampang (October) [Huay Tak Teak Plantation, 23 x 1986, 1 ♂, M. Hämäläinen leg.—M. Hämäläinen, pers. comm.] and Chaiyaphum (July) [Phu Khieo, 20 vii 1996, 1 ♀, A. Pinratana leg.—M. Hämäläinen, pers. comm.] Provinces of Thailand; Ng et al. 2011: 12, fig. 1—report for the Peninsular Malaysia, Cameron Highlands of 2 ♂♂ collected on 20 ix 2008 at Sg. Pos Terisu area and of 1 ♂ collected on 24 ix 2008 at Sg. Telom area; drawings of the variable pattern of synthorax of males from Malaysia, Cameron Highlands, and Thailand, Lampang and Tak Provinces

Lestes (Indolestes) anomala (Fraser) : Kimmins 1966: 178 —information on the holotype in the collection of British Natural History Museum: “ Holotype ♀. Indolestes anomala Fraser, Dalat , Siam, 17.x. 20, Type [label F.C.F.]. The locality given in the original description is Doun-moi, without date, but the specimen otherwise agrees.”

Indolestes anomalus: Day et al. 2012: 18 —report of 2 ♂♂, 1 ♀ collected on 09– 10.07.2011 in Thailand, Petchabun Province, Nam Nao National Park.

Specimens examined. Vietnam. 1 ♀ ( Fig. 3 ), Đỗng Nai Province, Cát Tiên National Park , 11.440 N, 107.422 E, 6 ii 2016, T. Kompier leg . Thailand: 2 ♂, 5 ♀♀ (1 ♂ ( Fig. 6 ), 1 ♀ ( Fig. 4 ) in tandem), Chaiyaphum Province, small muddy pond at Tung Lui Lai , 16.6089 N, 101.8906 E, 19 vii 1996, R.W. & J.A. Garrison leg.

The type locality. The type locality of I. anomalus was given in the original description as “ Siam: Doun-moi”. Siam is the historical name of Thailand, but no site with this or a similar name could be located in that country, so Hämäläinen & Pinratana (1999: page 32) noted that “The whereabouts of the type locality is unknown”, and Dow (2009) noted that “The type locality, " Siam, Doun Moi" ( Fraser 1946) cannot be relocated.”

“Doun Moi” might be variant spelling of “Than Moi” or “Than Muoi”, a place in northern Vietnam (or in Tonkin, as that was referred to at that time), well known for numerous insect specimens collected there by Hans Fruhstorfer in June–July 1901. Presently this location is called Đỗng Mỏ town, the capital of Chi Lăng District, Lạng SƠn Province (21.66° N, 106.58° E) ( Hämäläinen 2015). Thus “ Siam ” could result from a confusion with Tonkin or used in a sense to include all of Indochina. (For instance, the holotype of Macrogomphus borikhanensis Fraser, 1933 is labelled “Borikhane/ Laos, Siam ”, see Kimmins 1966). But the holotype label has no indication of the collector, which as a rule is present on labels of Fruhstorfer’s specimens.

However, Kimmins (1966) transcribed the holotype label ( Fig. 2d ) as follows: " Indolestes anomala Fraser, Dalat , Siam, 17.x.20, Type" and added: "Type locality given in the original description is Doun-moi, without date, but the specimen otherwise agrees". Kimmins (1966) noted a number of cases where actual labels of the type specimens did not coincide with information given by Fraser in his original descriptions. There are a Dalet or Dalat Town in Myanmar and Đà Lạt Town in Vietnam, the capital of Lâm Đỗng Province. The Cát Tiên District of the latter province is the location of the headwaters of the Đỗng Nai River. This river gave rise to the name of Đỗng Nai Thưọng commune in Cát Tiên District and Đỗng Nai Province (with the capital Biên Hòa), which borders Lâm Đỗng Province to the southwest. It is not clear which were the local toponyms and administrative divisions during Fraser’s time but it is very plausible that the holotype originated from the Đỗng Nai River basin in South Vietnam and that the river (or town) name was misspelled as “Doun-moi”. The original label of the specimen (or otherwise communicated information on the locality) could include both ‘Dalat’ and ‘Doun-moi’, two different toponyms from the same area, while Fraser included only the former on the label under the holotype and mentioned only the latter in the original description. “ Siam ” still was also an error or was used in too broad a sense. So any topotypes should be sought within the Đỗng Nai River basin in Lâm Đỗng Province or Đỗng Nai Province. Cát Tiên National Park is located along the Dong Nai River on the border between these provinces and so would be a good place to search for this species.

The holotype. The holotype is kept in Natural History Museum , United Kingdom (BMNH) under reference number NHMUK 0 13324318. Photographs of its details were kindly provided by Benjamin Price ( Fig. 2 ). The holotype is a somewhat teneral female in poor condition. The left hind wing and abdominal segments [hereafter S] 8–10 are missing (but were described in the original description).

There is a pair of pale spots on the occiput lateroposteriorly of the lateral ocelli, surrounding small tubercles, mentioned in the original description ( Fraser 1946). The synthoracic pattern ( Fig. 2c ) fits the drawing in the original description ( Fraser 1946: Fig. 1b ) where, however, the black spots at the posteroventral corner of the mesepisternum and anteroventral corner of the metepimeron were shown as smaller, while the dark stripe from the latter to the spiracle was shown as distinct although this is barely traceable in the holotype.

In describing the most conspicuous diagnostic character for the species, the pterostigma unusually short for Lestidae, Fraser (1946: 45) made somewhat confusing statements: “pterostigma ... of fore wing about one-third longer than deep, that of the hind-wing about half as long again as deep” meaning that the pterostigmata length in the fore and hind wings was, respectively, ca 1.33 and 1.5 times its height. Fraser did not mention which pterostigma he figures ( Fig. 2e ), showing the maximum length comprising 1.68 of the maximum width ( Fig. 1a ). The actual pterostigmata of the holotype are substantially longer: 1.90 times as long as high along the dorsal side and 2.25 times as long as high along the ventral side in the fore wing ( Fig. 2e ) and, respectively, 1.75 and 2.20 times as long as high in the hind wing ( Fig. 2f ). In both wings, the pterostigmata covers a bit less than two underlying cells ( Fig. 2e, f ), but one and half cells in Fraser’s figure. Fraser clearly stated that he had only one specimen and the BMNH specimen labeled as the holotype of “ Indolestes anomala ” fits very well in other respects, e.g. the synthoracic pattern, thus excluding the possibility of other specimens. The left hind wing is missing in the holotype ( Fig. 2a ); perhaps it had a shorter pterostigma, which Fraser may have figured and he may have detached that wing for convenience. Some of the discrepancies mentioned above between Fraser’s own figure and his textual description of the pterostigmata proportions indicates that he likely did not aim for high degree of accuracy of his measurements and/or drawings. Other incorrect proportions in Fraser’s drawings are well known (e.g. the wrong shape of the paraprocts shown for the lectotype of Lestes nigriceps Fraser, 1924 , see Kosterin 2018).

A nearly topotypic female. On 6 ii 2016 one of us (T.K.) collected a female in Cát Tiên National Park ( Fig. 3 ). It fits, with minor differences, the original description well. It displays the short pterostigmata ( Fig. 3b ), and has a pair of pale-coloured tubercles on the occiput, behind the lateral ocelli, a pair of dark spots on the anteclypeus, and a synthoracic pattern consisting of a posthumeral bronze stripe split into three irregular spots and a blunt projection of the dorsal bronze stripe at ca. three-fourths of its length ( Fig. 3a ). The central and posterior bronze spots on the mesepimeron are somewhat shorter ( Fig. 3a ) than in the holotype ( Fig. 2c ). The pale occipital spots extend lateroposteriorly of the pair of tubercles ( Fig. 3a ). The length of the hindwing is 20 mm (as in the original description); of the abdomen 28.5 mm (vs 27 mm in the original description).

The hind wing pterostigma of the female from Cát Tiên is 1.63 and 1.78 times as long as high along the dorsal and ventral margins, respectively ( Fig. 3b ), which is even shorter than in the holotype ( Fig. 2f ).

The characters of the end of abdomen differ considerably from the original description, which states “segments 8 to 10 dark brown with obscure indications of large yellow lateral spots. Anal appendages brownish, shortly conical”. This statement cannot be verified since the holotype lacks S8–10. In the Cát Tiên female, S8 is dark dorsally and pale ventrally and posteriorly, with a pair of smaller dark lateral spots, all colour transitions of which are diffuse; S9 dark becoming paler laterally, while S10 is entirely pale ( Fig. 3c ). Cerci are also pale with black tips and are conical but are as long as S10 ( Fig. 3c ). The colorational differences could result from the post-mortem changes or from the teneral state of the holotype, while the Cát Tiên female was photographed upon capture ( Fig. 3c ).

This was the only specimen collected during many visits to the park, nor has it been found during the extensive explorations of the area by James Holden (pers. comm.), so it may be rare. However, large parts of the park have not been surveyed.

Thai females. We have five females from a small muddy pond at Tung Lui Lai, Chaiyaphum Province, central Thailand collected by R. W. and J. A. Garrison. One female was collected in tandem with a male and is illustrated here ( Fig. 4 ). It has somewhat longer pterostigmata: 2.21 and 2.14 as long as high along the ventral margin in the fore and hind wings, respectively ( Fig. 4g, h ), which fits the holotype. The synthoracic pattern and such structural characters as a pair of pale-coloured occipital (postocellar) tubercles, although very slight ( Fig. 4b, c ), also correspond to I. anomalus , and the postocellar light spots are confined to the immediate circumference of those ( Fig. 4b, c ). The coloration of the end of the abdomen is similar to the Cát Tiên female, with S8 somewhat darker; and the cerci too are as long as S10 ( Fig. 4e ). The posthumeral dark spots are reduced in comparison with the holotype and Cát Tiên female: the posterior one narrow but parallel-sided, without a ‘neck’, the middle one small, the anterior one missing ( Fig. 4a ).

Measurements (N=5, in mm): Hw: 20–22.5, Abd. 27–31, total length: 35–38.

The photos from Nam Nao National Park in neighbouring Phetchabun Province by Dennis Farrell show mature females ( Fig. 5c, d ) in which the synthorax has a saturated blue ground colour, while that of the prothorax and mesepisternum is brownish. The pale colour of S1–3 and S10 is also blue, while S4–9 is brownish with indistinct darker dorsal spots expanding at the segment joints, with blue present only on the anterior margins of S4–7; the eyes are brownish-grey. Teneral females on his photos (not reproduced) have a brownish-grey ground colour.

Male. Since the male has not been described and its diagnostic characters remain unknown, we provide below a description of a male ( Figs. 6 , 7 ) collected in tandem with a female at Chayaphum Province of Thailand.

Habitus. Resembles the female, ground colour pale-bluish (further referred to as ‘pale’), dark pattern bronzeblack (further ‘dark’).

Head. Labrum, base of mandibles, genae and anteclypeus pale; postclypeus pale anteriorly, dark posteriorly, with a pair of large semicircular spots touching each other at base; epicranium and rear of head dark ( Fig. 6b ).

Thorax. Prothorax pale dorsally, with following areas dark: a pair of dorsolateral spots on middle lobe, wash of brown along dorsal margin of pleuron and a pair of ill-defined dorsolateral brown spots on rounded posterior lobe ( Fig. 6a,c ).

Synthorax ( Fig. 6c, d ). Mesepisternum with dark middorsal stripe occupying over half of mesepisternum, its sides parallel except for a small rounded lobe almost touching mesopleural suture at upper fifth and again at upper margin and with an offshoot extending posteriorly over mesopleural fossa; mesepimeron pale with following areas dark: irregular elongate spot extending posteriorly from mesopleural fossa and curving ventrally to level of semicircular spot of middorsal stripe, isolated irregular spot at middle of mesopleural suture and a small subtriangular spot at juncture of mesinfraepisternum, dorsal carina and upper fifth of interpleural and metapleural sutures dark; a narrow elongate dark spot bordering posterior margin of pale metinfraepisternum ( Fig. 6c ); venter of thorax as in Fig. 6d .

Coxae pale but diffusely brownish anteriorly. Femora black, becoming brown externally ( Fig. 6a, c ).

Wings hyaline; venation brownish. Postnodals: FW 10/11, Hw 10/10; RP 2 at Fw starts at postnodal 4/4, at Hw at postnodal 3/3. Pterostigmata: FW: 1.6 2–1.69/1.87–1.95 times as long as high (along dorsal/ventral side); HW 1.72–1.94/1.84–1.98 times as long as high, surmounting surmounting 1.5/cells in both wings. In one male specimen, costal vein at pterostigma is noticeably convex at FW and distinctly convex at HW; in the other male specimen it is only very slightly convex at both wings.

Abdomen with the following dark markings ( Fig. 6a ): S1 with a small dorsal quadrate spot at basal 0.30 and with narrow apical ring; S3–7 with a long dorsal stripe beginning at basal tenth, its base moderately expanded proximally and with a quadrate expansion laterally at distal end (that of S2 shaped as an inverted key-hole), but almost interrupted dorsally by an incomplete apical ring; basal 0.60 of S8 black, distal 0.30 pale, narrowly divided above by thin inverted triangular dark spot; S9 with irregular dark narrow basal ring, otherwise pale; S10 entirely pale, with a deep triangular dorsal incision.

Genital ligula ( Fig. 7 ) of usual lestine form, basal segment ovate, ectal arm with small semihyaline coiled tip that is grooved entally and ectally.

Cercus ( Fig. 6 e–g) with proximal half pale, becoming blackish-brown distally, mesal margin with a small semicircular lobe followed distally by a strong posteromedially directed tooth, apical third of cercus slightly swollen and attenuate distally; paraproct semicircular, black, about one-fifth the length of cercus.

Measurements (in mm): HW 20, Abdomen (including cerci) 32, total length 38

The other male specimen from the same series shows no significant differences. Mature males photographed by Dennis Farrell ( Fig. 5a, b, d ) have a saturated blue ground colour and dark-blue eyes with a green hue below, while these are brownish-grey in teneral ones (not shown); the expansion of the dorsal synthoracic dark stripe sometimes reaches the mesopleural suture and merges with the posterior posthumeral spot.

Habitat. In Cát Tiên National Park in Vietnam the female was found in January, which is during the dry season, in seasonally humid tropical forest with dense and thorny undergrowth. In Chayaphum Province of Thailand the species was found by R.G. at a small muddy pond. In Phetchabun Province, in Nam Nao National park, the species was regularly found in forest ponds, including a large one with reeds, from January to August, sometimes as extremely abundant ( Farrell 2018).

Distribution. The species is presently known from three separated areas: northern Thailand (Tak, Lampang, Phetchabun and Chaiyaphum Provinces), southern Vietnam (Đỗng Nai and possibly Lâm Đỗng Provinces) and Cameron Highlands in Peninsular Malaysia ( Fraser 1946; Day et al. 2012; Ng et al. 2011; Farrell 2018; this paper), as shown in Fig. 8 . It was observed as abundant only in Phetchabun Province of Thailand ( Farrell 2018). It can be expected in Cambodia, which lies between these regions.

Diagnosis. Indolestes anomalus is characterized by the synthoracic pattern with (i) the middorsal black stripe having a small extension at ca. three-fourths of its length and posteriorly expanding to the mesopleural suture and (ii) three irregular and variable posthumeral dark spots: an elongate dorsal one followed by a smaller quadrate one and finally by a smaller triangular spot at the margin of mesinfraepisternum (this small spot may be missing) ( Figs. 1a , 3a , 4a , 5 , 6a, c ). These spots rarely become confluent thus forming a broad irregular stripe confluent with the middorsal stripe (e. g. Ng et al. 2011: Fig. 1b ). The synthoracic maculation of I. anomalus differs from that in any other Asian Indolestes spp. Indolestes indicus Fraser, 1922 , I. gracilis gracilis (Hagen in Selys, 1862) and I. peregrinus (Ris, 1916) also have or may have a number of separate posthumeral spots, but in I. gracilis the dorsal dark stripe has straight margins whereas in I. indicus and I. peregrinus this stripe forms long trapezoid extensions medially rather than a small extension as in I. anomalus , but also expanding at the posterior end, like in I. anomalus ( Fraser 1933; Asahina 1976). The male cerci of I. anomalus ( Fig. 6 e–g) have attenuated apices similar to those of Indolestes cyaneus (Selys, 1862) , I. gracilis , I. guizhouensis Zhou & Zhou, 2005 (if this is a bona fide species) and I. peregrinus among Asian species (Kosterin 2015), but differ clearly from those species by the much larger and prominent, rounded inner swellings. Females have a characteristic pair of pale tubercles at the occiput lateroposterior of the lateral ocelli ( Figs. 3a , 4b, c ). Females resemble those of I. peregrinus by pale S10 and cerci contrasting with dark S9 ( Figs. 3c , 4a,d ). Pterostigmata at its ventral margin 1.8–2.2 as long as high ( Figs. 3b , 4f, g ); that is shorter than in the related species (e.g. 3.0– 3.2 in I. peregrinus ).

In his description, Fraser (1946) especially stressed the short pterostigmata of the holotype but it is longer than he depicted and becomes a less conspicuous diagnostic character. Nevertheless, it is still relatively shorter than in all other Indolestes species. Indolestes anomalus most resembles I. peregrinus , with which it shares separated posthumeral spots in both sexes, but differs by its smaller size and a more posterior position of the prominence of the dorsal synthoracic dark stripe. The large rounded inner swellings of the cerci in males ( Fig. 6 e–g) (almost absent e.g. in I. peregrinus ) and pair of pale, variably expressed postocellar tubercles in females ( Figs. 3a , 4b, c ) are good structural characters to identify I. anomalus .

Figures

FIGURE 1. The holotype (female) of Indolestes anomalus as illustrated in Fraser (1946): a—wing dorsoproximal part (after Fraser 1946: Fig. 2e); b—thorax (after Fraser 1946: Fig. 1c). Not to scale.

FIGURE 2. The holotype (female) of Indolestes anomalus (NHMUK 013324318) at BMNH: a—habitus, dorsal view; bhabitus, lateral view; c—head and thorax, lateral view; d—labels; e—right fore wing pterostigma; f—right hind wing pterostigma. Not to scale. Courtesy of Benjamin Price.

FIGURE 3. A nearly topotypical female of Indolestes anomalus from Vietnam, Đỗng Nai Province, Cát Tiên National Park, 6 ii 2016: a—head and thorax; b—hindwing; c—general habitus. Not to scale. Photo by Tom Kompier.

FIGURE 4. The female of Indolestes anomalus collected in tandem with a male in Thailand, Chaiyaphum Province, a small muddy pond at Tung Lui Lai, 19 vii 1996; a—body habitus; b—head, frontal view; c—head top, dorsofrontal view; dsynthorax, ventral view; e—tip of abdomen, lateral view; f—right wings; g—fore wing tip; h—hind wing tip. Not to scale. Photos by Rosser Garrison.

FIGURE 5. Indolestes anomalus photographed in nature in Thailand in Chaiyaphum Province, Phu Khieo Wildlife Sanctuary, 12 v 2016 (a) and Phetchabun Province, Nam Nao National Park, Suan Son Ban Baek, 15 viii 2015 (b–d); a, b—mature males; c—mature female; d—ovipositing tandem. Photo by Dennis Farrell.

FIGURE 6. The male of Indolestes anomalus collected in tandem with the female of Fig. 3 in Thailand, Chaiyaphum Province, a small muddy pond at Tung Lui Lai, 19 vii 1996; a—body habitus; b—head, frontal view; c—synthorax, lateral view; dsynthorax, ventral view; e—anal appendages, lateral view; f—ditto, dorsal view; g—ditto, dorsolateral view. Not to scale. Photo by Rosser Garrison.

FIGURE 7. The structure of the genital ligula of a male of Indolestes anomalus collected in tandem with the female of Fig. 3 in Thailand, Chaiyaphum Province, a small muddy pond at Tung Lui Lai, 19 vii 1996: a—ectal view; b—details of ectal arm, ectolateral view; c—lateral view. (Drawings by Rosser Garrison).

FIGURE 8. The known distribution of Indolestes anomalus. A—the locality of the nearly topotypical female shown in Fig. 3 (Vietnam, Đỗng Nai Province, Cát Tiên National Park) and approximately the presumed type locality; B—the locality of male and female shown in Figs. 4–7 (Thailand, Chaiyaphum Province, at Tung Lui Lai); C—the locality of a males shown in Fig. 6a (Thailand, Chaiyaphum Province, Phu Khieo Wildlife Sanctuary); D—the locality of individuals shown in Fig. 6b–d (Thailand, Phetchabun Province, Nam Nao National Park).