Davidioides martini Fraser, 1924

Sadasivan, Kalesh, Nair, Vinayan P., Pulikkal, Subash, Janaki, Sabari & Samuel, Abraham, 2023, Taxonomic notes on Davidioides martini Fraser, 1924 (Odonata: Gomphidae) and description of its female from Western Ghats, Peninsular India, International Journal of Odonatology 26, pp. 114-123 : 116-122

publication ID	https://doi.org/10.48156/1388.2023.1917211
persistent identifier	https://treatment.plazi.org/id/03AC9719-FFDB-FFAA-FFF8-F9B88FAFFBBB
treatment provided by	Felipe
scientific name	Davidioides martini Fraser, 1924
status

Treatment

Davidioides martini Fraser, 1924 View in CoL

( Figs 2–5 View Figure 2 View Figure 3 View Figure 4 View Figure 5 )

Davidioides martini View in CoL – Fraser, 1924: 472–473, Fig. 2 View Figure 2 (original description); Fraser, 1926: 419–420, Figs 3 View Figure 3 –6, Plate ii: Fig. 1 View Figure 1 ; Laidlaw, 1930: 188; Fraser, 1931: 447; Needham, 1932: 226

Specimens examined

4 ♂♂ and 4 ♀♀. TORG #1023 , ♂, Kakkadumpoyil , Nilambur, Malappuram District, Kerala, India, 28.v. 2023, 850 m a.s.l., col. K. Sadasivan. TORG #1024 ♂, 30.v.2023; TORG #1025 ♂, 31.v.2023; TORG #1026 ♂, 30.v.2023; TORG #1027 ♀, 31.v.2023; TORG #1028 ♀, 30.v.2023; TORG #1029 ♀, 31.v.2023, and TORG #1030 ♀, 31.v.2023, all bearing the following collection details: Nadukaani, Nilambur, Malappuram District , Kerala, India, 30.v. 2023, 700 m a.s.l., coll. K. Sadasivan.

Other specimens studied in the field (not collected)

2 ♂♂, and 2 ♀♀, from Thanuppan Chola , Nadukani , Nilambur, Malappuram District, Kerala, India, 30.v. 2023, 700 m a.s.l., (K. Sadasivan and S. Pulikkal) .

Description of male

( Figs 2 View Figure 2 , 4A–E, 4G–H View Figure 4 , 5E–F View Figure 5 )

Measurements (in mm) (n=4): TL 48–52, AL 32–37, FWL 35–38, HWL 32–33, HFL 5.

Head ( Figs 2A–D View Figure 2 ). Eyes greenish blue, anterodorsally darker, and inferolaterally pale bluish white. Genae black. Mandibles pale lemon-yellow. Labium yellowish white posteriorly, and anteriorly including the teeth black. Labrum black, bearing two large triangular yellowish blue patches on each half, its entire free edge thickly bordered with black. Anteclypeus pale lemon-yellow. Postclypeus shiny black. Antefrons and postfrons shiny black throughout, with a large pale lemonyellowish band in the upper area of the antefrons and expanding to the anterior area of the postfrons. The transverse band slightly concave in its middle. Vertex shiny black. Occipital bar slightly concave, matte black. Postocular lobe shiny black. Ocelli waxy white. Antennal flagellum and pedicel black, its scape ringed with yellowish white. Postgenae shiny black. Long pale amber-brown setae along the inferior border of the labrum and on the labium. Setae on the rest of the face black.

Prothorax ( Figs 2A, B, D View Figure 2 ). The general colour is black, and marked with lemon-yellow spots. In dorsal view, anterior lobe centrally broadly marked with yellow and laterally black; middle lobe black with a pair of small round paradorsal yellow spots; posterior lobe entirely black with its mid-dorsal aspect bearing a large yellow triangular spot, whole medial margin sinuous. In lateral view, the lateral aspect of the middle lobe with a large yellow triangular spot as mentioned above. Proepisternum and proepimeron black with a brownish tinge. Forelegs generally black, but lateral aspect of coxae dirty yellow, and medial aspect of femur with a large oval yellowish white patch, rest of the leg including the spines and claws black.

Synthorax ( Figs 2A–D View Figure 2 ). General colour black, marked with lemon-yellow stripes. In dorsal view,the mid-dorsal carina black, marked with yellow. Mesothoracic collar stripe yellow, well developed, passing over it and continuing to the other side; antehumeral stripes well developed, widely separated from the mesothoracic collar, minimally tapering towards the dorsum, L-shaped, almost reaching the antealar sinus dorsally, but turning laterally at a right angle as a continuous streak for a distance for almost one third of its length. In lateral view, the mesepisternum black, bearing the yellow mesothoracic collar and the antehumeral stripes. Mesokatepisternum dorsally black and inferolaterally marked with a bold yellow oblique stripe. Mesepimeron black, bearing a large anterosuperior yellow stripe extending dorsally and almost reaching the wing base. Metepisternum black and marked with a thin L-shaped yellow stripe that may be reduced to two small yellow spots on the posterodorsal aspect in well-marked specimens ( Fig. 2D View Figure 2 ). Metinfraepisternum mostly yellow, bordered with black. Metepimeron yellowish throughout sace for a thin black circumferential border. Poststernum yellow. Antealar sinus black, the intervening acrotergite region yellow. Scutum, scutellum, and postscutellum mostly yellow bordered with black. All sutures black. Metathoracic spiracle brown. Mid- and hindleg coxae dirty yellowish white; trochanter, femur, and tibia and claws black. Hind femur long, reaching the junction of abdominal sternites S1 and S2.

Wings ( Figs 2E View Figure 2 , 5E–F View Figure 5 ). Hyaline; Pt of both wings black, parallelogram-shaped, occupying almost four cells; borders slanting laterally; inferior border curvilinear. Pt length four times its breadth in its middle. Trigones (triangles) of forewing entire ( Fig. 5E View Figure 5 ), that of hindwing traversed by one vertical nervure ( Fig. 5F View Figure 5 ). Anal triangle in HW 4-celled. Nodal Range in FW: Ax 14–16 & Px 10–12; HW: Ax 10–12 & Px 11.

Abdomen ( Figs 2A, F, G View Figure 2 ). General colour shiny black, with pale lemon-yellow markings as follows: S1 dorsally on its distal border with a large triangular spot, the apex of which extends mid-dorsally towards the synthorax, and inferolaterally yellow. S2 bears a mid-dorsal spindle-shaped spot, two lateral yellow vertical streaks, a rounded triangular one enclosing the auricle, and another C-shaped, caudally convex one towards the posterolateral border. Another small spot antero-inferior to the yellow spot enclosing the auricle. Auricle yellow, its medial cranial border and the entire caudal border bearing the spine bordered with black. S3–6 marked with basal rings that end just short of the lateral carinae, ring with a width less than one eighth the length of the segments with posterior border excavated mid-dorsally by the black carina, ofen giving an appearance of paired spots in dorsal view. Dorsum of S7 marked with two yellow rings occupying just less than its basal half, these rings separated by a very narrow black streak dorsolaterally ( Fig. 2F View Figure 2 ). The yellow rings are interrupted laterally and terminate well short of the lateral carina of S7. A pair of small triangular spots on the posterior paradorsal aspect of S7 ( Fig. 2G View Figure 2 ). S8–10 unmarked.

Anal appendages ( Figs 2F–G View Figure 2 , 4C–E View Figure 4 ). General colour of cerci white in life (yellow in preserved specimens) with black basally and epiprocts entirely black; a little less than the basal fifh of the cerci and with five to six, small, short, black teeth on its ventral side. Length of cerci a little longer than that of S 10 in dorsal view. Cerci conical, divaricate and its lateral border slightly convex, medial border concave, and its tip pointed, directed posterolaterally. The whole surface bears short, bristlelike, brown setae. Lateral arms of the epiproct divaricate as the cerci, slightly shorter than the cerci, curved dorsolaterally, tips finely hooked. The whole surface bears blackish brown setae.

Secondary genitalia ( Figs 4A–B, G–H View Figure 4 ). Colour black, setae brown. Clef of anterior lamina (CAL) deep. Anterior hamule (AH) shorter than the posterior hamule in lateral view, long and narrow, flattened, with the tip rounded. Posterior hamule ( PH) with body broader than AH, tapering and curved uniformly towards its tip and directed anteromedially. Genital lobe (GL) slightly broader, but shorter than the PH, truncated, and its tip slightly curved anteriorly. The structure of the VS is illustrated in Figures 4G, H View Figure 4 . The median segment (S3) of the vesica spermalis in lateral view has a long digitiform extension directed ventroposteriorly, glans (S4) trumpet-like, with its tip expanded in the shape of a water lily leaf ( Fig. 4H View Figure 4 ).

Variation in males

The metepisternum is black and marked usually with a thin yellow stripe, but this may be reduced to two serial small yellow spots on the posterodorsal aspect in well-marked specimens (one in four). The L-shaped extension of the antehumeral stripe may occasionally be discontinuous in some individuals, forming a separate spot, but is never absent. The numbers of black teeth under the cerci vary from four to eight and may even vary between sides in the same specimen. The usual pair of small triangular spots on the posterior paradorsal aspect of S7 ( Fig. 2G View Figure 2 ) may be absent in heavily marked individuals. Venation is consistent in males with no variation in triangles observed, the FW is entire, and the HW triangle is always traversed.

Description of female

( Figs 3 View Figure 3 , 4F, I View Figure 4 , 5A–D View Figure 5 )

The female morphology is very similar to that of the males, the major differences are discussed below.

Measurements (in mm) (n=4). TL 52–55, AL 39–42, FWL 38, HWL 35–36, HFL 5–6.

Head ( Figs 3A–C, E View Figure 3 ). Colour and structure of eyes and head as in males. Occipital bar more concave than in males.

Prothorax ( Figs 3A–C View Figure 3 ). Colour and structure similar to those in males.

Synthorax ( Figs 3A–C, E View Figure 3 ). General colour black, with pale lemon-yellow markings. Colour and pattern as in the males. Mesothoracic collar stripe yellow, well developed, interrupted by the dorsal black carina. The extreme crest of the dorsal carina marked with yellow. Antehumeral stripes well developed, L–shaped, almost reaching the antealar sinus dorsally, but turning laterally at a right angle as a continuous streak for almost one third of its length. Metepisternum black and marked with a thin L–shaped yellow stripe that occupies its posterior part. Metathoracic spiracle dark brown, bordered with black. The mid- and hindleg coxae, trochanter, femur, and tibia are all black. Hind femur moderately long, reaching the junction of abdominal sternites S1 and S2.

Wings ( Figs 5A–D View Figure 5 ). Hyaline; Pt as in males. Nodal range in FW: Ax 14–17 & Px 10–13; HW: Ax 9–11 & Px 10–12. Venation as in males, but sometimes the superior triangle on the FW may be traversed even if only on one side ( Fig. 5B View Figure 5 ), and HW triangle not traversed ( Fig. 5D View Figure 5 ).

Abdomen ( Figs 3A, B, D View Figure 3 , 4F, I View Figure 4 ). General colour shiny black, marked with pale lemon-yellow as in the males. Abdomen slightly stouter than that of males. Auricle less conspicuous. Segmental markings on S1–6 as in males. Basal ring in S7 as in males, but the continuous yellow ring greatly reduced to a mid-dorsal streak. Distal parts of S7, S8 and S9 broader than in males. Hind femora extending to just short of junction of S1 and S2 only. S9 slightly shorter than S8. Abdomen only slightly longer than HW. Ninth abdominal sternite not differentiated into sclerotised plates. Subgenital plate (vulvar scale/vulvar lamina) is a pair of long triangular processes that almost reach the ventral half of the length of S8 ( Figs 4F, I View Figure 4 ).

Anal appendages ( Figs 3D View Figure 3 , 4F View Figure 4 ). General colour of cerci white and supra-anal plate black; cerci as long as S10, directed posteriorly, conical, tip with a small black tooth, the whole surface bearing white setae.

Variation in females

In females, the L-shaped extension of the antehumeral stripe may occasionally be disjunctive in some individuals but is never absent. The distal extension of the basal yellow annulus on S7 is sometimes reduced to a small triangular spot, but is always continuous with the basal annulus. The normal state of venation is non-traversed triangles in FW and traversed ones on HW ( Figs 5A, C View Figure 5 ), but occasionally the FW triangle may be traversed, too (1 in 4 females, unilaterally) ( Fig. 5B View Figure 5 ) and the HW triangle may not be traversed (1 in 4 females, unilaterally) ( Fig. 5D View Figure 5 ). Two of the three females caught had this abnormal venation in their triangles. In preservative, the cerci may take on a yellow colour, which is otherwise white in life in both sexes.

Distribution

The species is a mid-altitude one at between 400 and 900 m a.s.l. ( Fig. 1 View Figure 1 ). Kerala: Nilgiri–Silent Valley region: Silent Valley NP ( Babu et al., 2013, Nair et al., 2021; Subramanian, 2007; Subramanian et al., 2018), Nadukani in Nilambur (Kalesh Sadasivan & Sabari Janaki), Kakkadampoyil in Nilambur (Kalesh Sadasivan & Subash Pulikkal); Coorg: Kanichar (Vibhu Vijayakumaran), Kunnoth ( Fraser, 1924), and Aaralam ( Subramanian, 2009) in Kannur District. The visual records from the Lower Periyar area: Thattaekkad ( Varghese et al., 2014), Edamalayar and Agasthyamalai in Agasthyamalais ( Subramanian, 2009), and Nelliampathies-Anamalais, Cardamom Hills, and Pandalam Hills in Nair et al. (2021) need confirmation ( Fig. 1 View Figure 1 ).

Ecological notes

Males were spotted perching on rocks on the edges of hill streams in wet evergreen forests, basking in the morning sun. Some males were also seen inside shady jungle, sitting close to the ground on twigs and dead branches next to hill streams, with females perched on small twigs and rocks in the stream bed, busy ovipositing nearby. Egg-laying takes place in the clear water of small pools fed by seepages in these stream beds during the pre-monsoon season, in May and early June. Sympatric species observed were Protosticta gravelyi Laidlaw, 1915 , P. hearseyi Fraser, 1922 , Asiagomphus nilgiri- cus Laidlaw, 1922, Idionyx saffronata Fraser, 1924 , Idionyx corona Fraser, 1921 , Heliocypha bisignata (Hagen in Selys, 1853), Heliogomphus promelas (Selys, 1873) , Heliogomphus kalarensis Fraser, 1934 , Chlorogomphus campioni ( Fraser, 1924) , and Phylloneura westermanni (Hagen in Selys, 1860).