Lestes decipiens Kirby, 1893

Hopkins, Paul, Kosterin, Oleg E., Phan, Quoc Toan & Keetapithchayakul, Tosaphol Saetung, 2025, Taxonomic reconsideration of Lestes dorothea Fraser, 1924, L. decipiens Kirby, 1893, bona species, L. praecellens Lieftinck, 1937 and L. praemorsus Hagen in Selys, 1862 (Odonata, Lestidae), Zootaxa 5642 (5), pp. 451-475 : 459-468

Lestes decipiens Kirby, 1893

( Figs 1c–d ; 5e–h ; 8f–j ; 9–10 ).

Specimens examined. Cambodia: 2 ♂♂ ( Fig. 5e–h ) , 1 ♀, Mondulkiri Province, 15 km NNE of Sen Momorom , a large sedgy swamp, 12.550° N, 107.258° E, 570 m a.s.l., 27 vi 2018, O. Kosterin leg. ; 1♂, Stung Treng Province, Thala Barivat District, 32.5 km NNW Stung Treng, 9.5 km NE Sam’ang village , 13.798°– 13.800° N, 105.860°– 105.866° E, 81–85 m a.s.l., a rivulet with a pond, 27 vii 2016, O. Kosterin leg. ; 1 ♂, Kampot Province, Bokor Plateau, ‘Praemorsus Pond’ , 2.9 km NE Bokor Palace, 10.6456° N, 104.0392° E, 926 m a.s.l., 9 xii 2010, O. Kosterin leg. ; 1 ♂, Kampot Province, Bokor Plateau, the Popokvil River at the lower bridge, 4.9 km NE Bokor Palace, 10.6583° N, 104.0525° E, 926 m a.s.l., 18 viii 2011, O. Kosterin leg. ; 1 ♂, Preah Sihanouk Province, 11 km NE Sihanoukville, Kbal Chhay Waterfall env., a pond at the main river right bank, 10.674° N, 103.607° E, 53 m a.s.l., a rivulet with a pond, 26 v 2013, O. Kosterin leg. ; 1 ♂, Koh Kong Province, Thma Bang village, ‘ Triangularis pond’, 11.6703° N, 103.4086° E, 371 m a.s.l., 25 viii 2011, O. Kosterin leg. ; 3 ♂♂, Koh Kong Province, 13 km ENE Koh Kong, a grassy swamp at ‘ Aciagrion Rivulet’ source, 11.6600° N, 103.0956° E, 316 m a.s.l., 13 viii 2011, O. Kosterin leg. ; 1 ♂, Koh Kong Province, Koh Kong S suburbs, ‘ Calamorum ponds’ E of the road to Peam Krasaop village , 11.584° N, 102.985° E, 316 m a.s.l., 26 viii 2011, O. Kosterin leg. Thailand: 1 ♀, Nakhon Ratchasima Province, Wang Nam Khiao , 15 iii 2015, Makbun leg. ; 1 ♂, Krabi Province, Muang , 1 viii 2018, Makbun leg. Vietnam: 2 ♂♂, 2 ♀♀ (collected in tandems; Fig. 8f–j ), Quảng Nam Province, Nui Thanh District, Tam My Tay Commune , 15.3757° N, 108.5761° E, 46 m a.s.l., 16 x 2019, Q. T. Phan leg. ( ZCDTU) ; 1 ♀, Lam Dong Province, Bao Loc , 11.5288° N, 107.7082° E, 622 m a.s.l., 24 v 2023, Q. T. Phan leg. ( ZCDTU) ; 4 ♂♂, Kon Tum Province, Dak Glei , 15.2091° N, 107.7358° E, 1097 m a.s.l., 2 ix 2024, Q. T. Phan leg. (ZCDTU).

Characters. Male ( Fig. 5e–h , 9 ). The paraprocts are set more or less parallel to each other, so well seen in dorsal view ( Fig. 5e ). Because of this position, the paraprocts extend well behind the level of the cercus tooth ( Fig. 5f ). The length of the paraproct inner margin (as measured from the S10 border to the tip) comprises ca 46 % of the cercus length (as measured from the S10 border to the tip along the insect body axis). In ventral view ( Fig. 5f ), their outer margins are convex and inner margins slightly concave, so that their bluntly terminated apical parts, somewhat converge to each other, as seen also in dorsal view ( Fig. 5e ). In the oblique lateroventral view, the paraproct distal part is much broader and less S-like curved than in L. dorothea , with broadly blunt apices ( Fig. 5h ). In lateral view, the paraproct looks evenly tapering and slightly curved up, without distinction into the broader basal and narrower distal part. The appendages of the holotype of L. decipiens are damaged so that the right cercus and left paraproct are missing ( Fig. 9e ). However, the remaining paraproct corresponds perfectly to our recent specimens of L. decipiens : it is directed behind and has the same shape, slightly curving inwards.

Measurements (mm). Hindwing 19.5–20, 20.7 in the holotype; abdomen with appendages 29–29.5, 21.2 in the holotype.

Female ( Figs 10 , 12f–j ). The cerci in dorsal view are finger-like, narrowing only in apical part, pale entirely ( Figs 10e , 12g –h ). The ovipositor is but very slightly concave in lateral view ( Fig. 12f ); blackish, with pale areas at base ( Fig. 10d , 12f, h ). The genital lamina is blackish-brown at base and pale at posterior margin ( Fig. 12h ). The dorsal side of S10 black in the studied specimens ( Fig. 12g ), dark-brown in the female paralectotype ( Fig. 10e ). The prothorax hind lobe is almost upright, very scarcely slanting in lateral view ( Fig. 12i ) and looks rounded in dorsal view ( Fig. 12i ).

Measurements (mm). Hindwing 20–21 (mostly 20), 20.0 in the female paralectotype, abdomen with appendages 27.8 in the allotype, 26.5 and 30 mm in Vietnamese specimens, 29–30 (mostly 30) in Cambodian specimens.

The differences between males of L. dorothea and L. decipiens : confusion resolved

The initial identification of L. dorothea found at the Seima Forest on 8 vi 2024 was made on the field character of this species provided by Kompier (2024). He referred to the pruinosity of the male being restricted to S10 (as in Figs 2–3 ), whereas in Lestes decipiens it extends into S9 (as in Fig. 11 ) ( Kompier 2024). Kompier also made a reference to “strikingly different” inferior appendages of the male but did not explain the difference. In essence, the paraprocts are broadly divergent and hence concealed under the cerci in the male L. dorothea ( Fig. 5a–b ) and set close to each other in L. decipiens ( Fig. 5e–f ). This feature is not readily obvious as a field character and cannot be seen in Fig. 2 , although the photograph of a separate male from above ( Fig. 3 ) shows that the paraprocts are hidden by the cerci. In L. decipiens , the paraprocts are easy to see even in the field and in general photos, e.g. Fig 13 , because of their close proximity to each other (although in Fig. 13 the angle is oblique therefore only one paraproct can be seen). The difference in the paraprocts is clearly seen in the close-up photos of the Cambodian male specimens by OEK ( Fig. 5 ).

The above consideration of the striking diagnostic difference between L. decipiens and L. dorothea in the male paraprocts lacks references since it was never reported as such in literature, although follows from it implicitly. In the original description, Fraser (1924) characterised those of L. dorothea as “very short black-tipped with whitish hairs, extending only as far as basal spine of superiors, not visible from above, widely separated” ( Fraser 1924: 485). However, he did not mention them in the statement which can be considered as the differential diagnosis, which was as follows: ”Easily distinguished from elata by the shape of its dorsal thoracic bands and from praemorsa by its much larger size and by the absence of markings on sides of segments 8 and 9” ( Fraser 1924: 485). (Note that in L. decipiens from Cambodia ( Fig. 13 ) the blue lateral spots are indeed present on S8 but not on S9). The drawing of the end of abdomen of L. dorothea in dorsal view provided in the original description is adequate ( Fraser 1924: Plate XXXI, fig. 8; reproduced here in Fig. 1e ). The described coloration of the end of the abdomen in males of L. dorothea corresponds to the holotype, our specimens and the character pointed out by Kompier (2024): “8 to 9 entirely black save for a fine blue basal ring on 8, segment 10 pruinosed on the dorsum” ( Fraser 1924: 485).

The male paraprocts of the two species in question were also correctly described by Fraser in his famous monograph ‘Dragonflies of British India including Ceylon and Burma’ ( Fraser 1933). It is important to bear in mind that Fraser considered L. decipiens as a synonym of “ L. praemorsa praemorsa ”, although in fact the insects denoted with these names are quite different ( Lieftinck 1949; see the discussion below), and he had at his disposal only specimens of the taxon decipiens , from India, Sri Lanka and Myanmar. So in his citations below “ praemorsa ” should be taken as “ decipiens ”. For his “ L. praemorsa praemorsa ” (actually decipiens ), Fraser wrote as follows: “Inferior appendages much shorter, apposed at base, where they are very broad and rounded, then abruptly contracted to form a short, cylindrical, ungulate process tipped with stiff whitish hairs” ( Fraser 1933: 33). For L. dorothea he wrote: “Inferior much shorter, not visible from above, widely separated, thick at base, with a short ungulate process at apex tipped with whitish hairs” ( Fraser 1933: 36). However, his drawings of the end of the abdomen provided for both species ( Fraser 1933: figs 12–13) and reproduced here as Fig. 1f–g , showed the exactly opposite situation. The paraprocts are not seen from above in the drawing provided for “ L. praemorsa ” (that is for L. decipiens ) but actually showing L. dorothea (his fig. 12; Fig. 1f here), and are set closely to each other at base in the drawing provided for L. dorothea but actually showing L. decipiens (his fig. 13, Fig. 1g here). We have to conclude that these figures were accidentally confused and swapped places.

Maybe this unfortunate circumstance was a reason why this very obvious distinguishing character concerning the paraprocts has never been explicitly mentioned in scientific literature, and was mentioned but not explained in the blog by Kompier (2024). Something was wrong with this character, so people abstained from mentioning it. It is not excluded that the same occurred with Fraser himself when he prepared his monograph, since in his key for Lestes he provided the size as the only (and not so reliable) character distinguishing the two species, the size: “Small species, with abdomen 30–32 mm and hind wing 20–21 mm ” for “ L. praemorsa ” (that is for L. decipiens ) and “Larger species, with abdomen 36–39 mm, and hind wing 24–26 mm ” for L. dorothea ( Fraser 1933: 30) . His textual diagnostic note for L. dorothea was as follows: “Its much larger size and the absence of markings on segments 8 and 9 in the male, and its higher postnodal index, will serve to distinguish it from L. praemorsa ” ( Fraser 1933: 36) .

One can notice considering our Fig. 1e–g that the outline of the cerci of L. dorothea was shown quite differently in the original description ( Fraser 1924: Plate XXXI, fig. 8) ( Fig. 1e ) and the monograph by Fraser (1933: fig. 12) ( Fig. 1f ). The latter ( Fig. 1f ) showed them as relatively much longer, with the basal tooth well apart from the S10 margin. Discrepancies of different structural drawings by Fraser (1924) between each other and the reality has already been reported, including those of Lestes ( Kosterin 2019; 2020b). As seen from our Fig. 6c , showing the holotype of L. dorothea , and Fig. 5a , showing the Cambodian male, the drawing in the monograph ( Fig. 1f ) is closer to reality, except for the curvature of the distal part of the cerci, which in our insect ( Fig. 5a ) is as strong as in Fraser’s original description ( Fig. 1e ).

With respect to Fraser’s descriptions of the paraprocts, the following note is relevant: strictly saying, they are not shorter in L. dorothea than in L. decipiens . As can be inferred from their ventral views in Fig. 5b, f , the length of their inner margin (from the S10 border to tip) comprises ca 44 and 46% of the length of cerci (as measured from the S10 border to tip along the insect body axis). The actual difference is in their direction: they are more or less parallel to each other in ventral view ( Fig. 5b ) and directed mostly caudad in lateral and oblique views ( Fig. 5c, d ) in L. decipiens , while strongly divergent in ventral view ( Fig. 5f ) and more slanting up in lateral and oblique views ( Fig. 5g, h ) in L. dorothea . Because of this direction, they just reach the cercal tooth in L. dorothea ( Fig. 5b ) but strongly protrude behind them in L. decipiens ( Fig. 5f ). In ventral view, it may be noticed that the margins of the paraproct distal parts are nearly straight in L. dorothea ( Fig. 5b ), while in L. decipiens their inner margins are convex and the outer margin concave ( Fig. 5f ). However, these curvatures are seen in both species in the oblique lateroventral view ( Fig. 5d, h ). So, the question arises, if the difference between the two species in the paraprocts, so drastic in the dorsal view ( Fig. 5a, e ), could this be a matter of position/rotation rather than shape. However, the latter is not the case, since in L. decipiens the paraproct distal part is also much more thick, robust and blunt, and the distinction between the basal and distal part much less sharp ( Fig. 5e–h ) than in L. dorothea ( Fig. 5a–d ), so it cannot be rotated to occupy the position like in L. dorothea .

It can also be added that in his monograph, Fraser repeated the statement “segments 9 and 10 entirely black, the latter pruinosed white on dorsum” for L. dorothea but did not mention the pruinescence of the end of the abdomen in L. decipiens , thus missing the second valuable distinguishing character.

One can notice that the Indian specimens of L. dorothea are larger than the Thai/Indochinese specimens (the length of the abdomen with appendages respectively being 37–40 vs 35 mm).

The peculiar pattern of dark spots on the synthorax dorsum does not differ in L. decipiens and L. dorothea , that also follows implicitly from Fraser (1933).

Yokoi & Souphanthong (2014: fig. 5) provided a drawing (reproduced here as Fig. 1h ) of the anal appendages in dorsal view of a male from Laos, Champasak Province, Bolaven Plateau, Paksong, 1310 m a.s.l., 23 viii 2005, of an unidentified Lestes sp.1 , with no paraprocts seen. Most probably this was in fact L. dorothea , occurring in all neighbouring countries, which can hence be considered to be reported for Laos as well.

The differences in females of L. dorothea and L. decipiens

Fraser (1933) did not include female characters in his keys and did not indicate diagnostic ones in his descriptions. Our comparison of the proved females of L. dorothea from Thailand with those of L. decipiens from Vietnam ( Fig. 12 ) and with the photos of the allotype of L. dorothea ( Figs 7c–d , 8 ) and a female paralectotype (incorrectly designated as the “ allotype ” by Kimmins (1970)) of L. decipiens ( Fig. 10d–e ) revealed the following structural character: the cerci are gradually tapering, almost conical in dorsal view in L. dorothea ( Figs 8d , 12b ) but are finger like, narrowing only in apical part in L. decipiens ( Figs 10g, 10d ). The ovipositor lower margin is more noticeably concave in L. dorothea ( Figs 8c , 12a ) than in L. decipiens ( Figs 10d , 12c ). The structural difference was also observed in the hind lobe of the prothorax, which is almost upright in L. decipiens ( Figs 7e , 12i ) but more slanting in L. dorothea ( Fig. 12d ), but this character is rather quantitative. The females compared differ in many minor details of their pale maculation which may or may not be species characters, but the S10 dorsum is generally pale in L. dorothea ( Figs 8a, c–d , 12a–b ) and dark in L. decipiens ( Fig. 12f–g ); the cerci have black bases, lower sides and tips in L. dorothea ( Fig. 12b–c ) and entirely pale in L. decipiens ( Fig. 12g –h ).

The differences in the coloration of female S10 and cerci were mentioned in descriptions by Fraser (1933), as follows: for L. dorothea : “segment 10 entirely blue save for the mid-dorsal carina, which is finely black. Anal appendages small, conical, pointed, black” ( Fraser 1933: 36); for L. decipiens : “borders and apical ends of segment s 9 and 10 narrowly blue. Anal appendages creamy white, shortly conical, pointed” ( Fraser 1933: 33). The difference between the shape of the cerci was not mentioned while the difference in their colour was described as more drastic: black in L. dorothea (in fact not fully black) and pale in L. decipiens .

Assuming that the S10 ground colour not mentioned by Fraser for L. decipiens was black, we see the same drastic difference in the S10 coloration of females: dorsally mostly pale in L. dorothea and mostly black in L. decipiens . This character is well seen on photos and our analysis of those of both taxa uploaded to iNaturalist (2024) confirmed its validity. So, we may recommend the S10 colour as a good field character for females of these taxa.

Based on the above considered characters, we doubtlessly identified our female specimen collected without a male in Cambodia as L. decipiens .

Figures

FIGURE 1. Drawings of Lestes spp. (all males but i-right female) from literature, with original identifications: a, “Lestes praemorsus praemorsus”, Philippines, Luzon, Bilucao (Lieftinck 1949: fig. 19); b, “Lestes praemorsus praemorsus”, N. New Guinea, Hollandia (Lieftinck 1949: fig. 20); c, “Lestes praemorsus decipiens”, India, Coorg, Gonocopal (Lieftinck 1949: fig. 17); d, “Lestes praemorsus decipiens”, Indonesia, Java, Buitenzorg (Lieftinck 1949: fig. 18); e, “Lestes dorothea” from the original description (Fraser 1924: plate XXVI, fig. 8); f, “Lestes praemorsa” (in fact Lestes dorothea) (Fraser 1934: fig. 12); g, “Lestes dorothea” (in fact Lestes decipiens, restored in species rank in this paper) (Fraser 1934: fig. 13); h, “Lestes sp.1”, Laos, Champasak Province, Bolaven Plateau, Paksong (Yokoi & Souphanthong 2014: fig. 5); i-j, “Lestes praecellens”, holotype (i-left,-j) and allotype (i-right) from SW Java;, Oedjoeng Benteng Bay (Lieftinck 1937: figs 2–3); k–l, “Lestes praemorsus decipiens”, Taiwan (Asahina 1985: figs 25–26); m, “Lestes dorothea” (Orr 2005: 28); a-left, b-left, c-left, d-left, e, f-left, g-h, j-right, l-right, m-left–anal appendages in dorsal view; a-right, b-right, c-right, d-right, f-right, j-left–the same in lateral view; i-left, k–thorax in dorsal view; i-right, m-right–the same in lateral view. Not to scale.

FIGURE 2. Male of Lestes dorothea. 8 vii 2024. Seima Forest, Cambodia (PH).

FIGURE 3. Another male of Lestes dorothea. 8 vii June 2024. Seima Forest, Cambodia (PH).

FIGURE 5. Anal appendages of male specimens of Lestes dorothea (a–d) and L. praemorsus decipiens (e–h) collected at the same sedge swamp 15 km NNE of Sen Monorom, Mondulkiri Province, Cambodia, on 27 vi 2018; a,e–dorsal view; b,f–ventral view, c–g–lateral view; d–h–oblique lateroventral view. Scale bar = 1 mm. The pruinescence was washed off by acetone (OEK). Asterisk indicates the position of the paraproct tip.

FIGURE 6. The holotype of Lestes dorothea, from S. India, Coorg, Mercara, 17 iv1923, F.C. Fraser, male, preserved in the BMNH collection: a–dorsal general view; b–labels, c-e–the end of abdomen in dorsal, ventral and lateral views (photos by Dan Hall).

FIGURE 7. Thorax of the holotype, male (a,b), and allotype, female (c,d) of Lestes dorothea, in lateral (a, c) and dorsal (b, d) views (photos by Dan Hall).

FIGURE 8. The allotype of Lestes dorothea, from S. India, Greenfields, Sidapur. 26 iv1923, F.C. Fraser, preserved in the BMNH collection: a–dorsal general view; b–labels, c,d–end of abdomen in lateral and dorsal views (photos by Dan Hall).

FIGURE 9. The lectotype, male, of Lestes decipens, from Ceylon, Mahagany, 20 ix 1891, Yerbury: a–general habitus in lateral view; b–ditto in dorsal view; c–labels, d–end of abdomen in lateral view; e–ditto in dorsal view.

FIGURE 10. A paralectotype, female (incorrectly designated as “the allotype” by Kimmins (1970)) of Lestes decipiens, from Ceylon, 6th Milestone, Nilavelli Road, 9 xii 1891, Yerbury: a–general habitus in lateral view; b–ditto in dorsal view; c–labels, d–end of abdomen in lateral view; e–ditto in dorsal view.

FIGURE 11. The anal appendages of two male specimens of Lestes dorothea from India, Western Ghats, Kerala, Iduikki District: a–c–a pond at 10.0951° N, 76.9319° E, 4 vi 2024; d–f–a pool under a rocky slope by Mankulam Power House, 10.0965° N, 76.9345° E, 19 vi 2024; a–d–dorsal view; b–e–ventral view; c–f–lateral view.

FIGURE 12. The end of abdomen (a–c, f–h) and thorax (d–e, i–j) of female specimens of Lestes dorothea (from Thailand, Kanchanaburi Province, Kroeng Krawia) (a–e) and L. decipiens (from Vietnam, Quảng Nam Province, Nui Thanh, Tam My Tay; species rank restored in this paper) (f–j) collected in tandem with males: a, d, f, i–lateral view; b, e, g, j–dorsal view, c–h–ventral view; d mirrored.

FIGURE 13. A male of Lestes decipiens (species rank restored in this paper). 23 vi 2024. Siem Pang, Cambodia (PH).