Onychogomphus marijanmatoki Dow, 2014, sp. nov.

Onychogomphus marijanmatoki sp. nov.

(Figs. 1–12)

Material. Holotype: ♂ (SAR09_10_GOM30), Malaysia, Sarawak, Miri Division, Gunung Mulu National Park, Sungai Melinau Paku, flying over shallow riffle, 7 v 2010, leg. R. A. Dow. To be deposited in RMNH (Leiden).

Etymology. marijanmatoki, a noun in the genitive case, named after Marijan Matok (born 28th March 1972) of Ulm-Söflingen, Germany, in appreciation of his support of odonatological research in Malaysia through the International Dragonfly Fund.

Description of holotype male. Head (Figs. 2 –3): Labium mostly pale. Labrum mostly greyish-green becoming pale brownish cream laterally, narrow dark brown bands along free margin and adjacent to anteclypeus.

Mandible bases and genae pale. Anteclypeus with lower margin slightly expanded so overlapping labrum (Fig. 2), yellowish-brown coloured. Postclypeus dark centrally with yellowish-brown marks in lower lateral quarters. Ante- and postfrons not very sharply divided, dark brown with a yellow marking occupying most of postfrons (Fig. 3), narrowly divided centrally. Vertex and occiput black and brown. Tubercules behind lateral ocelli, ocelli yellowish.

Thorax: Prothorax almost entirely dark brown and black, pale along carina of anterior pronotal lobe. Synthorax dark brown with pale yellow markings as follows (Figs. 4–5): short mesothoracic collar narrowly separated from narrow antehumeral stripes that reach to approximately the apex of the antealar triangle. A broad stripe occupying most of mesepimeron, narrowing somewhat toward wing bases. A broad stripe occupying all of metepimeron except narrowly below metepleural suture. Venter obscurely dark and pale. Legs (Fig. 1) with coxae mixed yellowish, grey and brown, trochanters yellow and brown, rest mostly black, with brownish-yellow marks on flexor surfaces of femora, these most extensive on posterior legs where extending onto upper part of extensor surface. Wings (Figs. 6–7): Sectors of arculus well separated at origin with 2 (left) or 3 (right) crossveins before first bifurcation of superior sector in Fw and 1 in Hw. Discoidal field with two rows of cells from origin to ca level of nodus in both wings. 13 Ax in Fw, 9 in Hw, 11 (left) or 10 (right) Px in Fw, 9 in Hw. Pt brown, covering 4–5 underlying cells.

Abdomen: In dorsal view S1–2 moderately broad, contracting in apical half of S3, slender to S7 where it expands in apical half, maximum width at S8–9, then slightly more narrow on S10. Black with pale markings as follows (Fig. 1): S1–2 pale yellow laterally, including auricles, this colour deepening in distal half of S2, and a narrow yellow mid dorsal stripe, tapering to rear of S2. S3–6 with deep yellow basal markings, S7 with a more extensive deep yellow marking, occupying basal ca two–thirds of tergite. On S3 this marking partly divided dorsally, on S4–S7 narrowly but completely divided dorsally. S8–9 with lower part of sides orangey brown. S10 dark basally, largely yellow brown apically. Cerci yellow-brown in basal ca three-quarters, turning to brown apically, shaped as shown in Figs. 10, 11. Epiproct (Figs. 10, 12) dark brown becoming black apically, longer than cerci, deeply divided, the branches slowly dividing until apex, where abruptly out-turned. Accessory genitalia as shown in Figs. 8–9, terminal segment of genital ligula without cornua.

Measurements [mm]: Hw 25.5, abdomen without anal appendages 28.5, cerci ca 2.75, epiproct ca 3.

Diagnosis. A small member of the Onychogomphinae, with terminal segment of genital ligula not bearing cornua and epiproct just longer than cerci. Differs from all other named members of the Onychogomphinae for which the male is known and with epiproct not markedly shorter than cerci by the following combination of characters: terminal segment of genital ligula without cornua, seminal vesicle large but not very large and not rounded in profile, epiproct without basal third strongly downturned and without any dorsal spine or tooth visible in lateral view, merely a rounded hump in the basal half.

Remarks. O. marijanmatoki differs from the species described by Karube & Sasamoto (in press) in markings, details of accessory genitalia and penis structure and of the anal appendages. The male of Onychogomphus nigrescens Laidlaw, 1902 is not known, but the female, which is known only from peninsular Malaysia, differs from O. marijanmatoki in the markings of the thorax, which are stated by Laidlaw (1902: 80) to be “as in geometricus;” the markings of the pterothorax of O. geometricus Selys, 1854, are illustrated in Lieftinck (1929: 132, fig. 24). Although O. saundersii Selys, 1854, has been recorded from Sundaland, Lieftinck (1954: 93, footnote 1) noted that there is “a strong element of doubt about the occurrence of the genuine saundersii SELYS-HAGEN in Sumatra, and even within the boundaries of the Malaysian subregion.” In any case, the anal appendages and accessory genitalia of O. saundersii are illustrated in Selys Longchamps & Hagen (1858: plate 1, fig. 2), and although the anal appendages are somewhat similar to those of O. marijanmatoki, they differ in at least the length of the epiproct relative to the cerci and in the shape of the cercus; more importantly the penis of O. saundersii bears cornua on the terminal segment.

A number of genera have been erected within the Asian Onychogomphinae over the decades, but many of these have not been accepted by all authors. I prefer to follow the same conservative course as Müller & Hämäläinen (1993) and place the new species in Onychogomphus pending a thorough revision of the entire subfamily.