Drepanosticta carmichaeli (Laidlaw, 1915)

Phan, Quoc Toan, Yokoi, Naoto, Makbun, Noppadon, Joshi, Shantanu, Subramanian, K. A., Ngo, Quoc Phu & Dow, Rory A., 2021, A review of the Drepanosticta carmichaeli-group, with the description of D. wildermuthi sp. nov. from the Central Highlands of Vietnam (Odonata: Zygoptera: Platystictidae), Zootaxa 5067 (2), pp. 187-210 : 188-190

The Drepanosticta carmichaeli -group

In this study it was found that the subbasal spur on the paraprocts is only variably present in D. jurzitzai and is not present in D. annandalei and D. wildermuthi sp. nov. Since these species (especially D. wildermuthi sp. nov. and D. jurzitzai ) are clearly very similar to the other species in the group it is necessary to slightly modify the definition of the D. carmichaeli -group to include them. Additionally, all species in the group share a simple prothorax structure, which separates them from some other species of Drepanosticta from Sundaland. Here we define the D. carmichaeli -group as follows:

Species of Drepanosticta from west of Huxley’s line (which differs from Wallace’s line in its northern part, separating Borneo and the Palawan region of the Philippines from the rest of the Philippines, but merges with Wallace’s line between Borneo and Sulawesi, continuing southward through the Lombok strait) lacking horns or long processes on the anterior and posterior pronotal lobes of either sex. Cerci and paraprocts of similar length. The male with paraprocts of simple form, with at most a subbasal interior spine or spur, and lacking any spines or other protuberances, expansions, abrupt turns or twists in the apical half, and almost equally simple cerci, with either no dorsal modifications or only weakly developed interior-dorsal projections, and lacking clumps of long setae or any well-defined spines or spurs.

With this definition two additional species Drepanosticta sumatrana Sasamoto & Karube, 2007 and D. tenella Lieftinck, 1935 , both from Sumatra, are included, this is discussed further below. We have excluded species from east of Huxley’s line from consideration because although some are morphologically similar with D. carmichaeli and its allies (for instance at least some species of the D. moluccana -group defined by van Tol 2007), they are very unlikely to have any genuinely close relationship with them.

Within the D. carmichaeli -group most species have the dorsal surfaces of the head and synthorax entirely dark. Drepanosticta carmichaeli itself is the exception, with a pale bluish transverse band across the head and pale antehumeral markings as well as a (typically) brown dorsum to the synthorax ( Fig. 3a ). In D. annandalei , although there is no pale band across the head, some pale markings can be present dorsally on the synthorax (see Fig. 1a where a faint poorly defined paler area can be seen above the mesopleural suture near the wing bases), but these are poorly defined and never approach the antehumeral markings present in D. carmichaeli . In males of D. annandalei examined for this study, the subtriangular area defined by and including the bifurcated section of the middorsal carina behind the mesostigmal plates is pale ( Fig. 1a ). The prothorax is always simple in both sexes in this group, with at most slight lateral expansions to the rear at the dorsolateral margin of the posterior pronotal lobe ( Fig. 1c ).

The genital ligula of the species in the D. carmichaeli -group, where it has been studied, is rather simple, with a broad internal fold and a terminal segment narrower than the internal fold, divided into a pair of apical arms (concave between the arms) which themselves expand to some degree apically in most included species ( Figs 3e , 5c , 7e , 8e , 12d ).

The cerci of the species in the D. carmichaeli -group, as implied by the definition above, are mostly rather similar to each other, in dorsal view relatively broad at base with either no interior-dorsal projections (as in D. annandalei ) or a weak, flap or corner like interior-dorsal projection around the point where the cerci turn downwards in lateral view (as in D. carmichaeli ). In lateral view the cerci are usually directed slightly upward and taper from base, reaching a minimum (giving a rather pinched or petiolate appearance) at around half-length where they turn downwards and expand ventrally at least slightly, in most species this expansion is abrupt (the exceptions are D. wildermuthi sp. nov. and D. tenella , where the cerci only expand gently), sometimes with a distinct heel at the start of the expanded part (for instance in D. emtrai and D. vietnamica ) which often has a slightly blade-like appearance (for instance in D. hongkongensis ) when a distinct heel is absent. The Sumatran D. sumatrana has relatively straight cerci and a slight dorsal apical expansion but otherwise conforms to the above description. The subbasal spur on the paraprocts (referred to as basal by Fraser (1931b, 1933 but it is not actually at the base of the paraprocts), when present, can be from interiorly to dorsally directed and varies from a narrow spine to a fairly broad based, almost rounded structure; when not strongly dorsally directed (so easily visible in lateral view) it can be difficult to see. In almost all species included in the group the paraprocts, viewed ventrally, taper rather evenly after the base to a sharp or at least narrow apex. The exception is D. annandalei where in ventral view the paraprocts are of fairly even width and relatively robust in their apical half and have a rounded apex with a slight subapical interior hook. Because of its paraproct structure we consider D. annandalei to only provisionally belong to the D. carmichaeli -group and also retain some reservations about the inclusion of D. sumatrana .

Measurements of the species of the D. carmichaeli -group are summarized in Table 1 .

Figures

FIGURE 1. Drepanosticta annandalei ♂ [a, c, e, g, h, i] & ♀ [b, d, f, j], Bamboo Teri,Andaman Island, India (NZC). (a, b), head & thorax, lateral view; (c), head, dorsal view; (d), synthorax, dorsal view; (e, f), terminal segments of abdomen, lateral view; (g–i) appendages in lateral, dorsal and ventral view; (j), pterostigma, ♀.

FIGURE 3. Features of Drepanosticta carmichaeli ♂ [a–f], Darjeeling, India (NMNS) & ♀ [g–j], Arunachal Pradesh, Seijosa, India (NCBS). (a, g), head and thorax, lateral view; (b), abdominal tip, lateral view; (c, d), appendages in dorsal and lateral view; (e), genital ligula; (f), pterostigma; (h, i), prothorax in lateral & dorsal view; (j), abdominal tip, lateral view.

FIGURE 5. Drepanosticta emtrai ♂, Ta Thom, Laos (ZCDTU). (a), head and thorax in lateral view; (b), tip of abdomen; (c), genital ligula; (d), pterostigma.

FIGURE 7. Features of Drepanosticta jurzitzai, ♂ [a–e] & ♀ [f–h], Chantaburi, Thailand (ZCDTU). (a, f), abdominal tip in lateral view; (b, c), appendages in dorsal & lateral view; (d), paraprocts in ventral view; (e), genital ligula; (g), abdominal tip in dorsal view; (h), pterostigma.

FIGURE 8. Features of male Drepanosticta vietnamica ♂, Ta Thom, Laos (ZCDTU). (a), head & thorax, lateral view; (b), prothorax, lateral view; (c), abdominal tip, lateral view; (d), appendages, oblique dorsal view; (e), genital ligula; (f), pterostigma.

FIGURE 12. Drepanosticta wildermuthi sp. nov., holotype ♂. Appendages in (a), dorsal view, (b), lateral view & (c), ventral view; (d), genital ligula.