Relictanum

Miranda, Gil Felipe Gonçalves, Marshall, Stephen A. & Skevington, Jeffrey H., 2014, Revision of the genus Pelecinobaccha Shannon, description of Relictanum gen. nov., and redescription of Atylobaccha flukiella (Curran, 1941) (Diptera: Syrphidae), Zootaxa 3819 (1), pp. 1-154 : 85-86

Genus Relictanum Miranda gen. nov.

Relictanum Miranda gen. nov. (type species Baccha crassa Walker, 1852 ).

Included species. R. adspersitum Miranda sp. nov., R. braziliensis ( Curran, 1939) , R. crassum ( Walker, 1852) , R. fiametta ( Hull, 1943a) , R. johnsoni ( Curran, 1934) , R. magisadspersum Miranda sp. nov., R. nero ( Curran, 1939) , R. schwarzi ( Curran, 1939) , R. shropshirei ( Curran, 1930) .

Diagnosis. Head. Face narrow (between ¼ to 1/3 of head width) and mostly dark, rarely pale laterally; tubercle distinct and ventrally positioned ( Fig. 45a ). Frons normal (~1/3 of head width). Antennal insertions confluent. Female ocellar triangle ~1 ocellus-width from lateral eye margin. Dorsal occiput with 1 row of pile ( Fig. 45b ). Thorax. Scutum with anterior row of longer pile, entirely dark and usually without any discernible pattern of pollinosity. Scutellum entirely dark. Anterior anepisternum pilose. Katatergum with short microtrichia that gives the sclerite a ‘velvet’ appearance. Metaepisternum pilose. Metasternum bare. Dorsal lobe of calypter with normal pile on margin (but shorter than ventral lobe pile). Male metafemur with normal pile. Wing. Alula usually 2-3 times larger than c cell, rarely as wide as c cell. Wing hyaline or entirely light brown, usually entirely microtrichose. Abdomen. Abdomen petiolate, 2nd abdominal segment usually very narrow and long ( Fig. 44 g); abdominal tergites with pattern variable. Genitalia. Female 7th tergite rectangular with posterior margin concave ( Fig. 44 a); 8th tergite sub-quadrate to trapezoidal, usually with basal and apical margins concave ( Fig. 44 a) or notched ( Fig. 43 a); 10th tergite with apico-medial notch and fused apically or laterally to cercus; cercus setulate ( Figs. 43 a & b). Male subepandrial sclerite usually trapezoidal and with slightly extended posterior corners; surstylus sub-quadrate, with antero-apical corner extended ( Figs. 44 c & 47c); basiphallus teardrop-shaped, distiphallus membranous but with dorsal sclerotized triangular region.

Description. Male. Head: Dark brown to black. Face narrow, almost straight dorsal to tubercle, rarely pale laterally, with white pollen laterally, pollen sparse to absent on tubercle apex, usually white pilose laterally except black ventral to antenna, with distinct sub-ventral median tubercle, anterior oral margin sparsely white pilose; gena narrow (appears as an elongated triangle from ventral view). Lunule usually entirely black, sometimes pale above antenna insertion, bare, shiny. Frontal triangle entirely black, with dull brown pollen medially and silvery-white pollen laterally that sometimes is restricted to oval spots/triangles, usually with long, erect, black pile; ocellar triangle 1–1.5 times its length from posterior eye margin. Eye contiguity usually slightly shorter than vertical triangle length; antennal dark, basoflagellomere oval and at least slightly longer than wide, black pilose, arista dark red. Occiput usually with sparse dark pollen on dorsal ¼ and dense silvery-white pollen on ventral ¾, rarely entirely covered by white pollen (e.g. R. schwarzi ), dorsal ¼ with 1 row of simple black or scale-like white pile, middle 2⁄4 with 2–3 regular rows of pile, posterior row always with longer, scale-like white pile, anterior rows ranging from scale-like white pile to simple black pile, ventral ¼ with 2–3 irregular rows of white, scale-like pile, usually with shorter pile on anterior row.

Thorax: Prothorax dark, with sparse dull pollinosity but without pile. Scutum dark brown to black, dull pollinose, with a rectangular concentrated area of pollen anterior to scutellum; scutum markings, if present, formed by vittae of pale pollen; scutum pilosity usually erect, with anterior row of longer white pile that sometimes has shorter pile in the middle, notopleuron with pile longer anterior to transverse suture, and pile slightly thicker and densely arranged latero-posteriorly to transverse suture. Scutellum as dark as scutum, covered by dull pollen. Pleuron dark, with sparse white pollen, microtrichia longer on anterior ½ of katatergite (‘velvet’-like); pleuron pilose on anterior anepisternum, posterior ½ of posterior anepisternum, anterior anepimeron, ventro- and dorsoposterior katepisternum, katepimeron and sub-appressed on metaepisternum, pile on katepimeron and metaepisternum sometimes inconspicuous; metasternum dark, bare and very narrow dorso-laterally to metacoxa; metaepimeron flared laterally on posterior ½ being connected to body by a membrane; postmetacoxal bridge incomplete, metathoracic epimera widely separated. Dorsal lobe of calypter narrow, with marginal fringe of short pile; ventral lobe with long, branching pile.

Wing: Hyaline to entirely brown; alula linear to large, rarely with bare areas.

Legs: Procoxa with only 1 row of pile antero-apically, protrochanter bare ventrally, profemur with sparse pile on basal ½ and slightly longer pile on baso-ventral ½, with densely arranged pale pile ventro-laterally on apex of protibia and ventrally on protarsus. Mesofemur bare to sparsely pilose ventrally and with posterior row of longer black pile, mesotibia with ventro-apical short, thick, black pile, 1st and 2nd mesotarsomeres with densely arranged pale pile and short, thick, black pile intermixed ventrally, mesobasitarsus thinner than mesotibia and slightly thinner than other mesotarsomeres; metacoxa with distinctly longer pile, basal ½ of metafemur with only sparse pile ventrally, metatarsus usually entirely dark, metabasitarsomere with at most apex pale; pile color usually same as background.

Abdomen: Petiolate. First abdominal tergite crescent shaped, with long and erect pile laterally, usually bare or with shorter and sparse pile dorso-medially. Second abdominal segment narrow and very long. Third abdominal segment triangular to trapezoidal. Other abdominal tergites usually rectangular and wide. Sterna dark, well sclerotized. Genitalia: Small; epandrium and cercus densely microtrichose; epandrium trapezoidal in lateral view. Surstylus usually quadrate with slightly extended apical corner, base of surstylus articulated to epandrium apicoventrally. Subepandrial sclerite usually trapezoidal with slightly extended posterior corners and homogeneously sclerotized. Hypandrium usually sub-oval with a narrower quadrate apical ⅓, ventral surface usually bare, rarely with a few pile subapically (e.g. R. magisadspersum ). Postgonite narrow and elongated, with subapical acute dorsal extremity, and pilose on baso-ventral surface.

Female: Usually very similar to male except: frons narrow. Occiput dorsal pilosity and wing markings are sometimes different from the male. Sixth segment divided into tergite and sternite. Genitalia: 7th tergite rectangular with concave posterior margin; 7th sternite usually absent, sometimes rectangular, with extensive membranous region between 7th and 8th segments; 8th tergite sub-quadrate to trapezoidal and usually with basal and apical margins concave; 8th sternite reduce to pair of lateral rectangular/trapezoidal sclerites; 10th tergite with apico-medial notch, setulose and fused laterally or apically to cercus; 10th sternite, if visible, just a narrow sclerite with a few pile. Cercus densely pilose and with dorsal setulae.

Comments. These are small (length 5–10mm), petiolate flies, with the scutum entirely dark ( Fig. 44 g), usually with only 1 row of pile on the dorsal region of the occiput and with a very narrow 2nd abdominal segment.

Some species from the Ocyptamus caldus group with a bare metasternum resemble species of Relictanum , but the former are distinguished by the ventral rows of pile of the occiput distanced from the eye margin, the face wider than ⅓ of the head’s width, the wider 2nd abdominal segment, the enlarged surstylus and the distal portion of the distiphallus strongly curved anteriorly.

Etymology. The name is a reference to the word ‘forsaken’, referring to the way this clade is separated from the other “ tristis group” species (here treated as Pelecinobaccha ). The name Relictanum is to be treated as neutral.

Figures

FIGURE 43. Relictanum braziliensis (Curran, 1939). a – b. Female genitalia: a. Dorsal. b. Apex, lateral. c – f. Male genitalia: c. Surstylus, ventral. d. Epandrium, ventral. e. Hypandrium, lateral. f. Hypandrium, ventral. g. Holotype, habitus, dorsal. 8 tg: 8 th tergite, 10 tg: 10 th tergite, cerc: cercus, s scl: subepandrial sclerite.

FIGURE 44. Relictanum crassum (Walker, 1852). a – b. Female genitalia: a. Dorsal. b. Lateral. c – f. Male genitalia: c. Surstylus, ventral. d. Subepandrial sclerite, ventral. e. Hypandrium, lateral. f. Hypandrium, ventral. g. Male, habitus, dorsal. 8 tg: 8 th tergite, 10 tg: 10 th tergite, cerc: cercus, s scl: subepandrial sclerite.

FIGURE 45. a – e. Relictanum johnsoni (Curran, 1934), female: a – b. Head: a. Lateral. b. Dorsal. c – d. Genitalia: c. Dorsal. d. Lateral. e. Holotype, habitus, dorsal. f – h. Relictanum shropshirei (Curran, 1930), female: f – g. Genitalia: f. Lateral. g. Dorsal. h. Holotype, habitus, dorsal. 8 tg: 8 th tergite, 10 tg: 10 th tergite, cerc: cercus.