Arganthomyza Rohacek 2009
Creators: name: Roháćek, Jindřich
name: Barber, Kevin N.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Anthomyzidae
Arganthomyza

description: Genus Arganthomyza Roháček, 2009
Arganthomyza Roháček, 2009a: 59 [feminine]; ROHÁĆEK & BARBER (2013, partim): 7–9, 42–43 (redescription, phylogeny); ROHÁĆEK & TÓTHOVÁ (2014): 173 –174 (in-group phylogeny of the genus).
Type species. Geomyza socculata Zetterstedt, 1847: 2534 (original designation).
Diagnosis. (1) Head slightly higher than long, anteriorly rounded (rarely slightly angular). (2) Eye large, suboval to ovoid, with longest diameter slightly oblique subvertically. (3) Frontal triangle subshining to shining, relatively to very long. (4) Frontal lunule small but distinct. (5) Occiput slightly to distinctly concave. (6) Vertex (top of head) usually with silvery microtomentose spots or stripes between frontal triangle and posterior part of orbits. (7) Antenna geniculate, pedicel simple; (8) arista with sparse and relatively short ciliation. (9) Palpus yellow to brown, with 1 subapical seta and a few ventral setulae. Cephalic chaetotaxy: (10) pvt weak, convergent to crossed; (11) vti usually longest, vte, oc and posterior ors also long; (12) 2 long ors, anterior more or less shorter, 1–2 microsetulae in front of anterior ors; (13) a single row of small postocular setulae; (14) 1 long vi; subvibrissa weak, slightly to distinctly longer than peristomals; (15) peristomal setulae small and sparse. (16) Posterior corner of head rounded. (17) Antenna and face similarly coloured in both sexes.
(18) Thorax slightly narrower than head. Thoracic chaetotaxy: (19) 1 hu; 2 npl (anterior longer); (20) 1 very long prs (longer than anterior npl); (21) 1 very long sa, 1 long pa; (22) 2 very long (postsutural) dc, posterior dc longest of thoracic setae; (23) ac microsetae in reduced number, at most in 2 short rows, sometimes completely absent; (24) 2 sc, basal short and weak; (25) 1 minute ppl; (26) 2 stpl, posterior usually longer. (27) Legs unicolourous yellow, only apical tarsal segments with distal part contrastingly dark. (28) f 1 with strong posteroventral ctenidial spine. (29) t 2 with relatively short ventroapical seta. (30) Male f 3 with a posteroventral row of setae, having those in distal part shortened and thickened. (31) Wing relatively narrow and not very long; (32) wing membrane unicolourous or with longitudinal brown pattern. (33) C with small spinulae between apices of R 1 and R 2+3; (34) R 2+3 long, slightly to distinctly sinuate, subparallel with C; (35) R 4+5 slightly bent (recurved), subparallel with M apically; (36) discal (dm) cell long, widened distally, with r-m situated near its middle or slightly in front of it; (37) distal part of CuA 1 longer than dm-cu and almost reaching wing margin; A 1 short, ending far from it. (38) Alula small and narrow.
Male abdomen. (39) T1 and T2 usually only laterally fused (completely fused in A. setiplanta group only). (40) T2–T5 large and broad, all uniformly dark-pigmented. (41) S2–S5 narrow, as dark as terga or (secondarily) paler. Male postabdomen: (42) T6 reduced, short transverse, pigmented, submedially attenuated or unpigmented, bare. (43) S6 and S7 strongly asymmetrical, with 1–2 setulae each. (44) S8 less asymmetrical, long, setose in posterior half to two-thirds.
Male genitalia. (45) Epandrium of moderate size, as wide as high, with 1–2 pairs of longer dorsolateral setae in addition to shorter setosity. (46) Medandrium relatively broad, distinctly widened ventrally and narrower dorsally. (47) Cercus relatively large but weakly sclerotized and pale-pigmented, with pale setosity. (48) Gonostylus medium-sized to large, broader proximally and tapered distally, micropubescent on outer side, setose on inner side, with apex simple. (49) Hypandrium relatively robust, symmetrical and well sclerotized, with anterior inner lobes small and incurved, never projecting dorsally; (50) transandrium simple and slender, with more or less distinct caudal process that is nat and sometimes medially desclerotized. (51) Pregonite fused with hypandrial frame, shallow, usually with 2 (anterior and posterior) groups of setae and posteriorly with small to distinct ventrally projecting lobe; (52) postgonite slender, with distal part dilated and bent posteriorly, with 1 anterior setula, usually in proximal half. (53) Phallapodeme of moderate size, shallowly forked basally, bicuspidate apically. Aedeagus with (54) small, short and rather simple phallophore. (55) Distiphallus composed of distally membranous saccus and elongate sclerotized nlum. (56) Saccus with reduced armature, with only small unsclerotized tubercles; (57) nlum relatively short and robust, formed by two sclerites that are partly to largely fused and terminating in widened spinulose or denticulate apex. (58) Aedeagal part of folding apparatus nnely tuberculate and always striated; connecting sclerite narrow to very slender, nnely tuberculate or spinulose. (59) Basal membrane densely (usually pale) spinose. (60) Ejacapodeme relatively large, with slender digitiform projection.
(61) Female abdomen with broader, more transverse preabdominal terga and narrower sterna than in male; T1–T5 uniformly dark-pigmented. (62) Postabdomen relatively short, strongly tapered, partly telescopic. (63) T6 large, similar to T5, usually trapezoidal; S6 largest sternum and usually paler than T6. (64) T7+S7 fused, forming complete tergosternal subconical ring (only sometimes pale-pigmented ventrally, very rarely with S7 secondarily separated); (65) T8 about as long as broad, nat. (66) S8 rather short, longitudinally divided into 2 sclerites, having posterior bare parts bent dorsally, recurved and strongly invaginated. (67) Female genital chamber with only 1 pair of curved nat internal sclerites and with (68) one elongate (never transverse) annular sclerite lying below them; (69) ventral receptacle long, tubular and hyaline, with apex slender, straight or twisted; (70) accessory gland small, hyaline, at most with some nne grains on surface, and borne on slender, subterminally somewhat widened, duct. (71) Spermathecae (1+1) on short, basally inserted ducts (cervix present but weakly sclerotized to indistinct), pyriform to ovoid, with transversely ringed surface, basally with spine-like or bell-shaped appendages, rarely also with terminal invagination. (72) T10 very small, slightly transverse, dark, shorter than S10, with 1 medial pair of very long setae. (73) S10 simple, pentagonal, longer and slightly wider than T10. (74) Cercus medium-sized, usually pale (in contrast to dark-pigmented T10), with numerous nne setae (apical and dorsopreapical longest).
Discussion. This genus was established by ROHÁĆEK (2009a) to accommodate four species including the enigmatic East Palaearctic Arganthomyza barbarista Roháček, 2009. This concept was maintained by ROHÁĆEK & BARBER (2013) who expanded its diagnosis with the addition of 5 Nearctic species. However, because A. barbarista is transferred here (see p. 43) to the genus Ischnomyia Loew, 1863 and, in turn, Ischnomyia spinosa Hendel, 1911 proved to belong to Arganthomyza, see under A. vittipennis (Walker, 1857) below, the genus Arganthomyza had to be redenned accordingly above. This new taxonomic concept renders the genus more compact but less distinctly denned by apomorphic characters because the majority of apomorphies previously used to characterize Arganthomyza now proved to be synapomorphies demonstrating a sister-group relationship of Ischnomyia + Arganthomyza (see discussion under Ischnomyia).
Arganthomyza can be best characterized as follows: (1) head slightly higher than long and anteriorly rounded; (2) eye with longest diameter (subvertically) oblique; (3) frontal triangle relatively to very long; (6) vertex with silvery microtomentose spots or short stripes between frontal triangle and posterior part of orbits; (8) arista with sparse and relatively short ciliation; (20) 1 very long prs (longer than anterior npl); (21) 1 very long sa; (23) ac microsetae in reduced number, at most in 2 short rows, sometimes absent; (28) f 1 with strong posteroventral ctenidial spine; (47) male cercus relatively large but weakly sclerotized and pale-pigmented; (48) gonostylus broader proximally and tapered distally, with apex simple; (52) postgonite slender but with distal part dilated and bent posteriorly, with 1 anterior setula; (56) saccus with reduced armature, with only small non-sclerotized tubercles; (57) nlum relatively short and robust, formed by two, partly to largely fused sclerites terminating in widened spinulose or denticulate apex; (58) aedeagal part of folding apparatus nnely tuberculate; (64) T7 and S7 forming complete tergosternal ring (but can be pale-pigmented ventrally and very rarely with S7 secondarily separated); (67) female genital chamber with only 1 pair of curved nat internal sclerites and with (68) one elongate (never transverse) annular sclerite lying below them; (71) spermathecae on short ducts, pyriform to ovoid, basally with spine-like or bellshaped appendages; (72) female T10 very small, transverse, dark, much shorter than S10; (74) female cercus usually pale-pigmented.
Most of the characters in which Arganthomyza differs from Ischnomyia are apparently plesiomorphic or of unclear polarity (viz. 1, 2, 8, 20, 21, 28, 48, 58, 67, 68), and, consequently, only the following apomorphies seem to support the monophyly of Arganthomyza: (3) frontal triangle prolonged to very long, (52) postgonite with distal part dilated and bent posteriorly (but with 1 anterior setula present – this being the plesiomorphic state), (56) saccus with only small non-sclerotized tubercles, (57) nlum formed by two partly to largely fused sclerites, (71) spermathecae basally with spine-like or bell-shaped appendages and spermathecal ducts short. However, it should be noted that the shortened spermathecal ducts represent a rather weak synapomorphy because it also occurs as a homoplasy in the genera Fungomyza, Receptrixa and Reliquantha, and in a less pronounced form in some other groups (cf. ROHÁĆEK 2013c).
The phylogenetic hypothesis of interrelationships of Arganthomyza species inferred from the analysis by ROHÁĆEK & BARBER (2013), of course excluding I. barbarista, seems to be supported by molecular data (ROHÁĆEK & TÓTHOVÁ 2014). It is modined only by the addition of A. vittipennis which seems to belong to a separate clade forming a sister group to the clade with A. duplex group + A. socculata group (see discussion under A. vittipennis).
Nine species included: A. setiplanta (Roháček, 1987) (Oriental), A. versitheca Roháček, 2009 (E. Palaearctic) and A. carbo Roháček & Barber, 2013 (Nearctic) belonging to the A. setiplanta group; A. vittipennis (Walker, 1857) (Nearctic) forming the A. vittipennis group; A. acuticuspis Roháček & Barber, 2013, A. bivittata Roháček & Barber, 2013 and A. duplex Roháček & Barber, 2013 (all Nearctic) of the A. duplex group; A. disjuncta Roháček & Barber, 2013 (Nearctic) and A. socculata (Zetterstedt, 1847) (Holarctic) forming the A. socculata group. Only the Nearctic species are treated below – those fully described or redescribed previously by ROHÁĆEK & BARBER (2013) are provided with only abbreviated diagnoses and condensed listings of the material examined; additional, previously unpublished material is presented with complete data. For other species of Arganthomyza, see ROHÁĆEK (1987, 2009a) and ROHÁĆEK & BARBER (2013).
Key to identincation of Arganthomyza species (world)
1 Wing with longitudinal brown pattern (Fig. 85). Silvery microtomentose spots between frontal triangle and posterior part of orbits reduced to nne, often indistinct lines. No ac microsetae on mesonotum. Gonostylus with nnger-like attenuated apical part (Figs 91, 97); pregonite projecting ventrally and with single group of several setae (Fig. 92), basal membrane (Figs 92, 94) with large group of dense, pale, digitiform excrescences and connecting sclerite (Fig. 96) dark, well sclerotized. Spermathecae mushroomshaped (Figs 99, 100); female cerci brownish (Figs 98, 101). ....................................... ............................................................. A. vittipennis (Walker, 1857) (Canada, USA)
– Wing hyaline, unicolourous (Figs 84, 125). Silvery microtomentose spots between frontal triangle and posterior part of orbits distinct. At least some ac microsetae present. Gonostylus never digitiform terminally; pregonite nat, with small posterior process and two groups (anterior and posterior) of fewer setae each (Figs 72, 133), basal membrane with small group of short spine-like tubercles (Figs 73, 132, 172) and connecting sclerite (Figs 75, 135) very thin and membranous. Spermathecae differently shaped; female cerci pale ochreous to yellow. ............................................................ 2
2(1) Frontal triangle long, reaching anterior nfth to anterior margin of frons; pvt small, convergent but not crossed. Thorax and abdominal sclerites largely brown to blackish brown. Hind basitarsus with distinct thickened ventrobasal setae. Spermathecae nnely densely ringed (Fig. 81). Ventral receptacle broadly duct-like, suddenly attenuated to slender projection at apex (Fig. 77). ........................................................................... 3
– Frontal triangle shorter, at most reaching anterior third of frons; pvt small to distinct, always crossed. Thorax and abdominal sclerites of various colours (dark brown to yellow). Hind basitarsus without thickened ventrobasal setae. Spermathecae with robust transverse striae (Figs 140, 143,176). Ventral receptacle gradually attenuated towards apex (Figs 141, 142, 202). ............................................................................. 5
3(2) Head in pronle anteriorly somewhat angular. Frontal triangle not reaching anterior margin of frons. Thorax dark brown but with humeral and notopleural areas ochreous and scutellum medially pale brown. f 1 with ctenidial spine long and robust, as long as width of f 1 at its insertion (ROHÁĆEK & BARBER 2013: Fig. 9). Mid basitarsus proximoventrally with all setulae short. Male unknown. Female S6 broader (ROHÁĆEK & ARBER 2013: Fig. 28). Spermathecae regularly ovoid and both of the same size (ROHÁĆEK & BARBER 2013: Fig. 29). Annular sclerite in female genital chamber slender (ROHÁĆEK & BARBER 2013: Fig. 31). ................................ A. setiplanta (Roháček, 1987) (Nepal)
– Head in pronle anteriorly rounded (Figs 67, 164). Frontal triangle reaching anterior margin of frons. Thorax entirely blackish brown, or only ventral corner of sternopleuron ochreous to yellow. f 1 with ctenidial spine distinctly shorter than width of f 1 at its insertion. Mid basitarsus proximoventrally with 1–2 setulae enlarged and thickened. Female S6 narrower (Fig. 79). Spermathecae narrower, irregular and one often larger than the other (Fig. 81). Annular sclerite in female genital chamber robust (Fig. 82). ........................ 4
4(3) Face yellow (male) to dark orange (female); female palpus pale yellow. Pleural part of thorax unicolourous dark brown. Abdominal T1 and T2 only laterally fused. Gonostylus (ROHÁĆEK & BARBER 2013: Figs 33, 38) as long as epandrium is high, distally narrower; postgonite (ROHÁĆEK & BARBER 2013: Fig.34) not prolonged and less curved; nlum shorter and robust (ROHÁĆEK & BARBER 2013: Fig. 37). Female T8 subquadrate (ROHÁĆEK & BARBER 2013: Fig. 39); spermathecae (ROHÁĆEK & BARBER 2013: Figs 41, 42) with small basal spine-like appendages; internal annular sclerite nat and very robust (ROHÁĆEK & BARBER 2013: Fig. 46). ....................................... A. versitheca Roháček, 2009 (Korea)
– Face dark, greyish brown in both sexes (Fig. 68); female palpus brown. Sternopleuron with ventral corner ochreous to yellow (Figs 67, 164). T1 and T2 completely fused. Gonostylus shorter than height of epandrium, distally broader (Figs 71, 76); postgonite prolonged and strongly curved, sickle-shaped (Fig. 72); nlum longer and more slender (Fig. 75). Female T8 anteriorly rounded (Fig. 78); spermathecae with more robust basal appendages (Fig. 81); annular sclerite less robust (Fig. 82). ................................ .................................................... A. carbo Roháček & Barber, 2013 (Canada, USA)
5(2) Thorax yellow, except mesonotum (Fig. 109) with a pair of narrow longitudinal brown vittae (rarely missing) and sometimes also dorsal margin of pleuron darkened. Medial rows of ac microsetae long (reaching to posterior dc); scutellum with several microsetulae in addition to 2 sc setae. All preabdominal sclerites yellow to pale yellow (except for lateral darkening of terga caused by internal reddish to brown tissue) and with long and dense setae. Gonostylus (Figs 128, 130) simple, with acute apex, strongly incurved (Fig. 129). Female postabdomen with T6 and S6 yellow (Figs 136–138); tergosternum T7+S7 also pale, darkened only laterodorsally and on transverse anteroventral submarginal ledge-like band (Figs 136, 137); spermathecae broadly ovoid (Figs 140, 143). .................................................................................... ................................................. A. bivittata Roháček & Barber, 2013 (Canada, USA)
– Thorax brown to dark brown, at most with ventral half of pleuron paler. Medial rows of ac microsetae short, reduced, in at most 3 pairs; scutellum bare except for sc setae. At least preabdominal terga (usually also sterna) dark brown to brown, with setae shorter. Male genitalia and female postabdominal structures different. .................................. 6
6(5) Thoracic pleuron bicolourous (brown dorsally, ochreous to yellow ventrally, see Figs 108, 146). Preabdominal sterna sexually dichroic (brown in male, pale yellow in female). Gonostylus relatively small, bent posteriorly (Figs 151, 156) and medially (Fig. 150). Female T6, S6 and ventral portion of T7+S7 pale-pigmented (Figs 158, 159). Spermathecae (Fig. 157) pyriform, with basal appendages adpressed to surface. ........ ................................................... A. duplex Roháček & Barber, 2013 (Canada, USA)
– Thoracic pleuron unicolourous brown to dark brown. Preabdominal sterna brown or pale brown, unicolourous in both sexes (thus dark also in female). Male genitalic and female postabdominal structures different from above. ............................................. 7
7(6) Gonostylus basally wider, strongly tapered distally and with apex acute (Figs 111, 116). Pregonite with posterior pair of setae arising on membrane behind posterior process; postgonite distally prolonged posteriorly and very narrow (Fig. 112). Filum of distiphallus with longitudinal sclerites only partly fused, basally dilated (Fig. 115) and its apex almost without spinulae (Fig. 114). Spermathecae with small spiniform basal appendages (Figs 117, 120). Female genital chamber with a nattened sclerite near base of ventral receptacle in addition to usual annular and paired internal sclerites (Fig. 124); ventral receptacle with apex twisted (Fig. 121). .................................................. .......................................................... A. acuticuspis Roháček & Barber, 2013 (USA)
– Gonostylus basally narrower, gently tapered distally and with apex rounded (Figs 170, 175, 189, 194). Pregonite with posterior pair of setae arising on tip of posterior process; postgonite distally dilated (Figs 171, 190). Filum of distiphallus with sclerites fused and basally narrow (Figs 174, 193) and its apex distinctly spinulose (Figs 173, 192). Spermathecae with large bell-shaped appendages (Figs 176, 196, 200). Female genital chamber with only the usual annular and paired internal sclerites (Figs 180, 183, 198); ventral receptacle with apex bent (Figs 179, 202). .................................... 8
8(7) Gonostylus more slender and longer, with longer apex distinguished also by anterior concavity (Fig. 175). Hypandrium anterior to pregonite hardly excavated and pregonite with posterior process larger (Fig. 171)*. Female S7 separate from T7 (Fig. 178); each spermatheca (Fig. 176) with only 3 bell-shaped appendages (some can be doubled); annular sclerite very elongated, particularly posteriorly (Figs 180, 181). ..................... ............................................... A. disjuncta Roháček & Barber, 2013 (Canada, USA)
– Gonostylus more robust and shorter, subapically concave only posteriorly (Fig. 194). Hypandrium anterior to pregonite with distinct excavation (Fig. 190) and pregonite with posterior process small, slightly projecting*. Female S 7 integrated into tergosternum T7 +S7 (Fig. 201); each spermatheca (Figs 196, 200) with 5–6 bell-shaped appendages (some can be doubled in Nearctic specimens); annular sclerite markedly shorter (Figs 197, 198). .................................................................................................. ....................................... A. socculata (Zetterstedt, 1847) (Palaearctic, USA: Alaska)
description: Published as part of Roháćek, Jindřich & Barber, Kevin N., 2016, Nearctic Anthomyzidae: a monograph of Anthomyza and allied genera (Diptera), pp. 1-412 in Acta Entomologica Musei Nationalis Pragae (suppl.) (suppl.) 56 on pages 56-61, DOI: 10.5281/zenodo.4272829