Coeliccia scutellum Laidlaw, 1932

Steinhoff, Philip O. M. & Uhl, Gabriele, 2015, Taxonomy and nomenclature of some mainland SE-Asian Coeliccia species (Odonata, Platycnemididae) using micro-CT analysis, Zootaxa 4059 (2), pp. 257-276 : 258-262

Coeliccia scutellum Laidlaw, 1932

Coeliccia tomokunii Asahina, 1997 has been considered a junior synonym of C. scutellum Laidlaw, 1932 ( Wilson & Reels 2001) . Asahina (1997: 24) indicated this possibility in his original description of C. tomokunii and suggested that “...a careful comparison of the type specimen is needed between the two species.” In order to test this possible synonymy we compared the lectotype of C. scutellum with specimens that were collected near the type locality of C. tomokunii , since the type specimens of C. tomokunii are not accessible and may be lost.

Descriptions and illustrations of specimens are provided and compared with the original descriptions by Laidlaw (1932) and Asahina (1997). Laidlaw (1932) gave only a short description and a rough sketch of the thoracic markings of C. scutellum , whereas Asahina's (1997) description includes illustrations of the head, thorax and anal appendages of C. tomokunii .

Material examined. Type material: 1♂ Lectotype: Bao Ha, Tonkin ( Vietnam), 20.04.1924, leg. H. Stevens [ BMNH, NHMUK 010266912].

Other material: Total 6♂: 1♂ Mt. Tam Dao, Vinh Phu Province, northern Vietnam, 1994, leg. M. Hämäläinen [ RMNH]. 1♂ “Stream below Thac Bac” Tam Dao, Vinh Phu Province, northern Vietnam, 26.06.2008, leg. M. Hämäläinen [ RMNH]. 1♂ same locality, 28.06.2008, leg. M. Hämäläinen [ RMNH]. 3♂ “Rhododendron & Fivelakes trail” Bach Ma National Park, Thua Tien Hue Province, central Vietnam, 15– 18.06.2008, leg. M. Hämäläinen [ RMNH].

Description of the lectotype. Head ( Fig. 2 A): Completely black except for diffuse greyish patches reaching out apically from the ocelli; typical postocular spots only just visible, the coloration faded away almost entirely. Prothorax ( Fig. 2 B–C): All black, posterior lobe slightly raised.

Synthorax ( Fig. 2 B–C): Black dorsally, with two big yellow markings ( Fig. 2 B). Synthorax laterally black with two big yellow markings, the lower one covering most of the metepimeron, the upper one covering the posterior part of the metepisternum up to the metathoracic spiracle, dorsally reaching slightly onto the mesepisternum. A small but distinct black spot near the upper margin of the metepisternal yellow marking; mesepisternum black.

Wings ( Fig. 2 G–H): Hyaline with black Pt, covering nearly two cells in Fw and Hw. 21 Px in Fw, 20 Px in Hw. RP 2 arising slightly proximal to Px 10 in Fw, between Px 7 and Px 8 in Hw. IR1 arises at Px 13 in Fw, and at Px 11 in Hw. IR2 arises slightly distal to subnodus in all wings.

Abdomen: Slender, black with whitish lateral spots on S3–6.

Anal appendages ( Fig. 2 D–F): Paraprocts slightly overtopping cerci in length. Cerci with small, medially directed spine on upper inner border; followed dorsoapically by a rounded elevation, and with distinct ventromedial tooth arising subapically. This tooth is difficult to see in the lectotype, as the cerci are turned so that the tooth is rather directed inwards.

Genital ligula ( Fig. 5 A–B, Supplementary Fig. 1 ): First segment simple with distal bend; second segment curved with well-developed inner fold, without terminal fold; third segment flat, median part distinctly raised, with two recurved flagella arising medially from raised part, bordering first segment.

Measurements (mm): Lectotype: Total length: 49, Abd.: 42, Fw/Hw (left): 21.

Measurement ranges of the six studied specimen collected near the type locality: Total length: 55–61, Abd.: 47–52, Fw (left): 29–34, Hw (left): 29–34.

Variation. Head ( Fig. 3 A): Specimens from near the type locality show more extensive whitish coloration reaching out from the lateral ocelli towards the antennal bases, which have a whitish base; postocular spots distinct, yellowish white.

Synthorax ( Fig. 3 B–C): Lateral yellow markings of the specimens from near the type locality agree well with the lectotype, but there is great variation in the extent of the two dorsal, escutcheon-shaped spots. In some specimens they cover about one third of the dorsal part of the synthorax as in the lectotype; in other specimens the spots cover up to two thirds of the dorsal synthorax ( Fig. 3 B–C). The coloration, described by Laidlaw (1932: 22) as “…citron or sulphur-yellow…” also varies in the specimen from the type locality; some specimen have citron markings as in the lectotype, while in others the markings are of a rather deep golden yellow color ( Fig. 3 B–C).

Anal appendages ( Fig. 3 D–F): In some of the other specimens examined, the anal appendages dried in another position than in the lectotype, so that the ventromedial tooth is directed straight downward and the small spine is directed rather obliquely inward ( Fig. 3 D–F). Asahina (1997: 23) did not describe the anal appendages for C. tomokunii but mentioned that the superior appendages are “provided with inflated head…”. Depending on the position of these appendages, this impression may arise from the rounded dorsoapical elevation.

Genital ligula ( Fig. 5 C–D, Supplementary Fig. 2 ): All specimens from near the type locality with two small thin flaps arising laterally from raised median part of segment three, posterior of origin of flagella ( Fig. 1 C, 5 C– D). Flaps missing in the lectotype.

Remarks. The specimens of Coeliccia scutellum studied show rather strong variation in coloration, size and shape of dorsal markings. In order to visualize this variability, we illustrate a specimen that is most different from the lectotype in all mentioned characters ( Fig. 3 ). The genital ligula of all examined specimens, differs from the genital ligula of the lectotype in having two thin lateral flaps on segment three ( Fig. 1 C, 5 C–D). The lectotype is the only specimen without flaps on the genital ligula, although the shape of the ligula is otherwise consistent with that found in the other specimens. Since there are no other structural differences between the lectotype and the other examined specimens, it seems possible that the flaps have eroded in the lectotype. Alternatively, within the 70 years that passed between the collection of the lectotype and the collection of the other specimens examined the genital ligula might have changed due to sexual selection or genetic drift. It seems also possible that there is variation in the shape of the genital ligula, with the lectotype without flaps representing the extreme end of the variability.

As the somatic and genital variability is strong between lectotype and all other examined specimens, we suggest that C. tomokunii is synonymous with C. scutellum . Investigating the variability in a long series of C. scutellum , in particular the assessment of whether there is continuous variation in flap size or bimodal distribution, would help to clarify the taxonomic status. We propose the following synonymy:

Coeliccia scutellum Laidlaw, 1932

Syn. Coeliccia tomokunii Asahina, 1997 , syn. nov.

Figures

FIGURE 1. Mounting methods and detail of genital ligula. A Pinned specimen (Coeliccia scutellum) mounted for micro-CT scan, B papered specimen (Coeliccia scutellum) mounted for micro-CT scan, C macro-photograph (Zeiss MCr Camera) of C. scutellum genital ligula, showing thinness of flaps. Scale bar: 250 Μm.

FIGURE 2. Coeliccia scutellum Lectotype. A head dorsolateral, B prothorax and thorax dorsal, C prothorax and thorax lateral, D anal appendages lateral, E anal appendages dorsolateral, F anal appendages dorsal, G left Fw, H left Hw. Scale bars: 500 Μm.

FIGURE 3. Coeliccia scutellum Tam Đ ảo, Vietnam. A head dorsolateral, B thorax dorsal, C thorax lateral, D anal appendages dorsal, E anal appendages lateral, F anal appendages dorsolateral. Scale bars: 500 Μm.

FIGURE 5. Genital ligulae as reconstructed from micro-CT (orientation bars: dl dorsolateral, l lateral, p posterior, v ventral, vl ventrolateral). A – B Genital ligula of C. scutellum lectotype C – D genital ligula of C. scutellum from Tam Đ ảo, Vietnam E – F genital ligula of C. hainanense lectotype.