Eumerus druk Smit, 2020

Smit, John, Zeegers, Theo & Dorji, Phurpa, 2020, A new species of Eumerus (Diptera, Syrphidae) from the Kingdom of Bhutan, the easternmost representative of the bactrianus subgroup, ZooKeys 906, pp. 141-151 : 141

publication ID

https://dx.doi.org/10.3897/zookeys.906.48501

publication LSID

lsid:zoobank.org:pub:46D77D87-0F79-40CD-A661-0E545EEA42F1

persistent identifier

https://treatment.plazi.org/id/5BBC6AD2-F2BF-4726-A26E-6055791AFE79

taxon LSID

lsid:zoobank.org:act:5BBC6AD2-F2BF-4726-A26E-6055791AFE79

treatment provided by

ZooKeys by Pensoft

scientific name

Eumerus druk Smit
status

sp. nov.

Eumerus druk Smit sp. nov. Figs 1A-F View Figure 1 , 2A-E, G View Figure 2

Type locality.

Bhutan, Thimphu.

Diagnosis.

Body golden-coppery, except t2 and t3 medially and t4 basomedially: shiny black amplified by short adpressed black pile. Basoflagellomere rectangular, with a rounded posterior corner. Male: abdomen t3 and t4 laterally with long, silvery, ventrally directed pile; s4 without an incision posteriomedially but medial part of sternite less sclerotized. Basotarsomere of metaleg simple, equal in length to the rest of the tarsomeres. Male terminalia: posterior surstyle lobe with a tuft of long pili just anterior to the bifurcation.

Description.

Male. Length of body (excluding antennae) 7.5-8.5 mm, length of the wing 5.5-6.5 mm. Head. Eyes holoptic, eye contiguity 9-10 ommatidia long, ommatidia near eye contiguity conspicuously larger than those in the posterior part (Fig. 1E View Figure 1 ). Eye margins ventrally slightly divergent. Eye covered with dense white pile; posterior eye margin bare. Face with dense, silvery-white pollinosity and white pile. Frons with golden-yellow pile, intermixed with black pile or even predominantly black pilose on the ocellar triangle. Ocellar triangle isosceles; distance between anterior ocellus and posterior ocelli compared to the distance between both posterior ocelli 1:0.55. Frons with a small pollinose macula anterior to anterior ocellus. Occiput with dense white pollinosity up to about 3/4 dorsally; dorsal part shiny black, with coppery luster. Antenna black; basoflagellomere rectangular (Fig. 2D View Figure 2 ), with a rounded posterior corner. Arista entirely black. Scape and pedicel black, with white pile; black pile dorsally; dorsal pile much shorter than ventral pile.

Thorax. Entirely shiny black, with golden luster (Fig. 1D View Figure 1 ). Mesonotum with a pair of white pollinosity vittae covering 3/4 of scutal length. Mesonotum and scutellum covered with golden-yellow pile; clearly longer near the posterior margin of the mesonotum and scutellum. Notopleural suture absent. Scutum next to wing base with a row of strong black setae. Scutellum with a broad rim, somewhat granular. Anepisternum and anepimeron with the same golden luster; katepisternum pollinose, with a small shiny spot dorsally, posterior to tuft of long white pile, ventrally with a few long white pili. Legs. All black, except for the tibiae, which are red on the basal third. Tarsi black, claws bicoloured, red basally, and black apically. Metafemur moderately swollen, slightly curved, with two rows of black setae apicoventrally, 11 on anterior ridge and 11-13 on posterior ridge, long white pile dorsally, about half as long as the maximum width of the femur and even longer white pile ventrally, the longest ones slightly more than 3/4 the maximum width (Fig. 1B View Figure 1 ). Metatibia with a flange of adpressed setae on the basal half, ventrally, followed by a shallow notch, apicoposteriorly with a single row of long light pile, longer than the maximum width of the metatarsus. Basotarsomere of metaleg simple, equal in length to the rest of the tarsomeres. Wings. Hyaline, pterostigma light brown, entirely microtrichose.

Abdomen. Entirely black, parallel sided, t2-4 with oblique maculae of white pollinosity, those on t3 and t4 longer and clearly lunulate (Fig. 1A View Figure 1 ). t2 and t3 shiny black medially, as well as t4 basomedially, laterally with golden-coppery luster (Fig. 1D View Figure 1 ). The black colour in the middle of the tergites is amplified by the short adpressed black pile, light on the pollinose maculae as well as on the lateral sides and the majority of the t4. Abdomen with conspicuous long, silvery, ventrally directed, white pile on the lateral sides of the t3 and t4 (Fig. 1C View Figure 1 ). s4 with long silvery-white pile laterally, distinctly shorter medially, posteromedially without incision, but medial part of sternite less sclerotized (Fig. 2E View Figure 2 ).

Terminalia (Fig. 2A-D View Figure 2 ). Posterior lobe of sursylus bifurcate, with a tuft of long light pile just anterior to bifurcation.

Description of female.

Similar to male except for the normal sexual dimorphism (Fig. 1F View Figure 1 ). Length of body (excluding antennae) 7 mm, length of the wing 6 mm. Head. Frons with some pollinosity alongside the eye-margin, from the antennae up to the anterior ocellus. Ocellar triangle isosceles, distance between anterior ocellus and posterior ocelli compared to the distance between both posterior ocelli 1:0.88. Abdomen. t3 and t4 laterally with slightly longer, silvery and ventrally directed, pile.

Etymology.

The specific epithet ‘druk’ is Dzongkha (the Sino-Tibetan language spoken in Bhutan) for dragon and refers to the official name of the kingdom: Druk yul (country of the Dragon people, or the Land of the Thunder Dragon). It should be treated as a noun in apposition.

Distribution.

This species is only known from the type series collected at the Royal Botanical Garden in Thimphu, Bhutan, but it likely has a wider distribution in the Himalayas. This is the only Eastern Palaearctic species of the bactrianus subgroup of the strigatus species group.

Examined material.

Type material. Holotype Bhutan • male; Thimphu, Royal Botanical garden; 27.425N, 89.650E, 2400 m a.s.l.; 26 April 2018; J.T. Smit & Th. Zeegers leg.; RMNH.INS1092470.

Paratypes Bhutan • 4 males; same collection data as for holotype • 1 female; same data as for holotype; RMNH.INS1092471.

The holotype is in good condition and is deposited, together with one male and female paratype in the National Biodiversity Center, Bhutan (NBCB). The remaining three paratype males, as well as the DNA material are stored in the collection of Naturalis Biodiversity Center, the Netherlands (NBC).

Remarks.

The male of Eumerus druk Smit, sp. nov. is easily distinguished from all other species in the bactrianus subgroup by the long, silvery, ventrally directed, pile on the lateral sides of t3 and t4. Eumerus banaticus has some longer pile on the lateral sides of t4, but this is shorter, not ventrally directed, and not present on t3. Furthermore E. banaticus is easily distinguished by the lack of pollinose maculae on t4 and by the shape of st4 and the terminalia. Eumerus hungaricus Szilády, 1940 and E. pulchellus Loew, 1848, which have similar long, ventrally directed pile on t3 and t4, are superficially similar but the pile is much more dense. Eumerus druk Smit sp. nov. can easily be distinguished by the bifurcate posterior surstyle lobe. E. hungaricus and E. pulchellus furthermore lack the golden-coppery luster on the thorax and abdomen of E. druk . Eumerus pulchellus is a more slender built species, with a more bluish luster, a relatively slender metafemur, the pro- and mesotarsi predominantly light brown, the basoflagellomere orange. Eumerus hungaricus is a more black species with less luster, especially on the abdomen, which is predominantly black pilose; s3 is very slender, about 2.5 times longer than wide, and t4 has a yellow posterior margin, medially.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Syrphidae

Genus

Eumerus