Eristalinus brunettii Roy, Naskar & Banerjee sp. nov.

urn:lsid:zoobank.org:act: 4A4C7F2E-0792-4EBE-A7E1-7AD822D5A903

Figs 1–3, 7A–C

Diagnosis

The species is well distinguished from morphologically similar species by a combination of the following features: scutum entirely black, without pruinose vittae in males (Fig. 1A), or indistinct pruinose vittae sometimes present laterally in females (Fig. 3A). The anterior half of the wing has a distinct yellowish brown infuscation (Fig. 1A–B), indistinct in females (Fig. 3A). The terga are mainly orange with a black posterior margin and median vittae on terga II–III (Figs 2D, 3D). In male, the ventral margin of the surstylus is sinuous at the middle (Fig. 7C).

Etymology

The species is named after Enrico Adelelmo Brunetti to honour his immense contribution to the Indian Diptera, especially Syrphidae. The specific name brunettii refers to his surname and should be treated as a noun in the genitive case.

Type material

Holotype

INDIA – West Bengal • ♂; Hooghly, Arambagh; 22.86355° N, 87.80362° E; 15 m a.s.l.; 20 Apr. 2024; B. Roy leg.; sweep netting; GenBank no.: PQ615094; NZSI.

Paratypes

INDIA – West Bengal • 1 ♀; same collection data as for holotype; GenBank no.: PQ615095; NZSI • 1 ♂, 3 ♀♀; same collection data as for holotype; NZSI • 1 ♀; Murshidabad, Malipara; 24.15341° N, 88.37381° E; 40 m a.s.l.; 8 Mar. 2020; Banerjee and party leg.; pan trap; GenBank no.: ON421642; NZSI • 4 ♂♂, 3 ♀♀; Birbhum, Suri; 23.906383° N, 87.527732° E; 71 m a.s.l.; 7 Mar. 2024; B. Roy leg.; sweep netting; NZSI • 2 ♂♂, 3 ♀♀; Hooghly, Arambagh; 22.86355° N, 87.80362° E; 15 m a.s.l.; 26 May 2024; B. Roy leg.; sweep netting; NZSI.

Description

Male

MEASUREMENTS. Body length 6.0– 8.5 mm, wing length 5.5–7.5 mm, FH 0.19–0.24, WM 2.08–2.31.

HEAD (Fig. 2A–B). Eye holoptic, yellow, with dark patches, pilose on the dorsal half, eye contiguity about 12–16 facets long; vertical triangle shining black, fully occupied by ocellar triangle, entirely covered with black pile, ocelli dark red; frons shining blueish black with black pile, lateral margin narrowly pruinose; face yellowish grey pruinose with shining blueish black median vitta, facial pilosity pale yellow; facial tubercle moderately developed, gena and subcranial cavity black; occiput black with greyish white pruinosity, pilosity black dorsally and greyish white ventrally; antennae yellowish orange, postpedicel about 1.9 × as long as wide, dorsal half dark brown, arista dark brown, bare.

THORAX. Mesonotum shining black with blue reflection, covered with dense, erect black pile; scutum without pruinose vittae; postpronotum and anterolateral area of scutum before transverse sulcus with pale yellow pruinosity; pleura black, with greyish white pruinosity on posterior half of anterior anepisternum, anterodorsally on posterior anepisternum, posteriorly on anepimeron, anterodorsally on katepisternum and meron; pleural pilosity pale yellow mainly, intermixed with black pile on anterodorsal part of anepimeron; anterior anepisternum and meron bare; posterior anepisternum densely pilose anterodorsally, rest of pleura comparatively sparsely pilose (Fig. 2C). Wings with distinct yellowish brown infuscation on anterior half, veins dark brown, pterostigma brown; calypters blackish grey (Fig. 1A); haltere orange. Legs mainly black; pale yellow at apex of pro- and mesofemur, apical half of protibia, whole mesotibia, extreme apex of metatibia, apical 1–2 tarsomeres of pro- and mesoleg, and basitarsomere of metaleg; pile on leg black and yellow intermixed; yellow on basal ⅔ of meso­ and metafemur and basal ⅓ of profemur; black pile on rest of profemur, dorsally on pro- and mesofemur, entirely on metatibia, intermixed with yellow pile on pro- and mesotibia; pile on tarsomeres of all legs yellow and black intermixed, shorter and denser than those on femora and tibia; presence of black setulae at basolateral extreme of all tibia, and apico-laterally on all tarsomeres.

ABDOMEN (Fig. 2D). Abdomen yellowish orange; tergum I with shining black area at middle; terga II– III with black posterior margin and median black vittae; tergum IV with or without median black vitta and posterior margin narrower than that on terga II–III; tergum V completely black; pile on abdomen yellow, except on black part, laterally on terga II–III, and anterolateral corner oftergum II with black pile (Fig. 2D); sterna I–III yellow, rest of sterna brownish black, pilosity on sterna yellow (Fig. 1B).

GENITALIA (Fig. 7A–C). Cercus sub-triangular, wider than high; surstylus rounded on extreme apex with black reclinate setulae (Fig. 7B), anteriorly with a few pile and scattered setulae, ventral margin of surstylus sinuate at the middle (Fig. 7A); hypandrium curved, almost uniformly broad throughout its length, postgonite with 2 ventral projections, one apical and one sub-medial, nearly equal in length (Fig. 7C).

Female (Fig. 3)

Body length 5.5–7.2 mm, wing length 5.8–7.0 mm, FH 0.27–0.30, WM 2.06–2.25. Similar to male except for normal sexual dimorphism and following characteristics: eye dichoptic, bare; postpedicel about 1.6× as long as wide; area anterior to vertex, frons and face along eye margins greyish white pruinose, pile on frons black; mesonotal pile yellow intermixed with black ones; tergum III with incomplete posterior margin and a trace of black vitta, pile on anterolateral corner of tergum II yellow.

Biology

Eristalinus brunettii Roy, Naskar & Banerjee sp. nov. exhibits a preference for high­flying behaviour, typically frequenting the canopies of tall woody trees such as Mangifera indica L. (Anacardiaceae) and Syzygium cumini (L.) Skeels (Myrtaceae). The species also occurs occasionally on ground-cover vegetation and agricultural lands.

Distribution

West Bengal (India).

Remarks

Specimens identified herein as Eristalinus brunetti sp. nov. were previously treated as morphological variants of E. polychromata due to similarities in the general habitus and abdominal colouration. Detailed morphological examination, however, revealed consistent differences in the body pilosity, colouration, wing infuscation, and the structure of the surstylus and postgonite, separating these specimens from E. polychromata (Table 2). Additionally, the female specimen ON421642 (NZSI), earlier identified as E. polychromata (Kar et al. 2024), was re-examined and found to exhibit the diagnostic characters defined for E. brunetti; molecular analysis further recovered this specimen within the E. brunetti clade. Accordingly, the specimen is here assigned to E. brunetti as a paratype.