Anthomyza occidentalis Roháćek & Barber 2016, sp. nov.
Creators: name: Roháćek, Jindřich
name: Barber, Kevin N.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Anthomyzidae
Anthomyza
Anthomyza occidentalis

description: Anthomyza occidentalis sp. nov.
(Figs 337, 339, 343–356, 377)
Type material. HOLOTYPE: ♂, “ USA: OR: Lane Co., Tokatee Klootchman St.Nat.Site., ~7.9kmS Yachats, 10.vi.2009, KN Barber, sweeps, mostly E. tel-mateia, Angelica, base of cliff 44°12.47’N 124°06.90’W ” and “ Holotypus ♂ Anthomyza occidentalis sp. n., J. Roháček & K. N. Barber det. 2014” (red). The specimen (largely yellow coloured, Fig. 339) is in good condition, with partly visible gonostylus (DEBU, intact). PARATYPES: CANADA: BRITISH COLUMBIA: Milner, 12.vii.1953, 1 ♀, G. J. Spencer leg. (CNCI, genit.prep., right wing missing). UNITED STATES OF AMERICA: CALIFORNIA: Cambria, Santa Rosa Creek Trail, 35°33.94'N 121°06.03'W, sweeps, Equisetum telmateia braunii & Delairea odorata under canopy, 3.v.2014, 1 ♀, 4.v.2014, 1 ♂, K. N. Barber leg. (LACM); Mendocino Co., Inglenook Fen, fen area, 30–50', 11.viii.1972, 2 ♂♂ 1 ♀ (1 ♂ 1 ♀ genit. prep., 1 ♂ with det. as Anthomyza pallida), 22.vii.1972, 2 ♀♀ (1 ♀ genit. prep.), E. I. Schlinger leg. (EMEC, UCIS- 215194, -233, -249, -597, -599); Marin Co., 2 air mi W. Inverness, 1.v.1976, 1 ♀, J. Doyen & P. Rude leg. (EMEC, genit. prep.); San Francisco Co., Lake Merced, 7.v.1927, 1 ♂, C. L. Fox leg. (genit. prep., wing illustration); San Francisco, Lake Merced, collected with night trap in willow thicket, 21.vi.1964, 2 ♂♂ (both genit. prep.), collected in willow thicket near lake, 1.viii.1964, 3 ♂♂ (2 ♂♂ genit. prep.), P. H. Arnaud Jr. leg.; Humboldt Co., McKinleyville bog area nr. Azalea Avenue, 9.vii.1980, 1 ♂ 1 ♀ (1 ♂ genit. prep.), T. W. Davies leg. (all CASC); Morro Bay, 27.vii.1940, 1 ♂ (genit. prep.), A. L. Melander leg.; Pacinc Grove, 4.vii.1921, 1 ♂, A. H. Sturtevant leg. (both USNM); Marin Co., Point Reyes, 19.iv.1980, 1 ♂ 1 ♀, S. A. Marshall leg. (DEBU); Humboldt Co., Prairie Ck. Redwoods S. P., Elk Prairie Cmpgd., 41°21.63'N 124°01.73'W, sweeps, riparian Scirpus sp., 8.vi.2009, 1 ♂, K. N. Barber leg. (CNCI); Rosemead, 17.iii.1950, 1 ♂ 1 ♀, A. H. Sturtevant leg. (USNM); Los Angeles Co., Rosemead, 17.iii.1950, 5 ♂♂ 4 ♀♀ (3 ♂♂ 1 ♀ genit. prep.), 22.iii.1950, 1 ♂ 1 ♀ (1 ♂ genit. prep.); San Mateo Co., San Francisco, 18.v.1950, 2 ♂♂ 2 ♀♀ (1 ♂ 1 ♀ genit. prep.), all M. R. Wheeler leg. (all AMNH); San Francisco, 1.viii.1915, 1 ♂, A. L. Melander leg. (USNM, genit. prep.). OREGON: Curry Co., Cape Blanco, 29.vi.1972, 1 ♂, W. N. Mathis leg.; Curry Co., 8 mi N Gold Beach, 29.vi.1972, 3 ♂♂ 1 ♀ (2 ♂♂ 1 ♀ genit. prep.), G. Steyskal leg. (all USNM); Curry Co., Samuel Boardman S. P., Lone Ranch Beach, 42°06.07'N 124°20.76'W, sweeps, mostly Equisetum telmateia, 3.vi.2009, 2 ♂♂; Lane Co., Tokatee Klootchman St[ate] Nat[ural] Site., ~ 7.9 km S Yachats, 44°12.47'N 124°06.90'W, sweeps, mostly E. telmateia, Angelica, base of cliff, 10.vi.2009, 5 ♂♂ 3 ♀♀, all K. N. Barber leg. (CNCI 4 ♂♂ 2 ♀♀, 1 ♂ 1 ♀ genit. prep., SMOC 1 ♂ 1 ♀, both genit. prep.). WASHINGTON: Friday Harbor, 6.vii.1905, 1 ♂ 2 ♀♀, J. M.Aldrich leg. (USNM, 1 ♂ 1 ♀ genit. prep., 1 ♀ with det. as Anthomyza pallida Zett.); Pierce Co., Tacoma, 22.vi.1982, 1 ♀, T. L. Whitworth leg. (LACM); Whidbey Island nr. Keystone Ferry, 18.ix.1975, 1 ♀, G. F. Hevel leg. (USNM).
Other material examined (not included in type series). UNITED STATES OF AMERICA: CALIFORNIA: Asilomar, 1.ix.1945, 1 ♂, A. L. Melander leg. (headless, genit. prep.); Pacinc Grove, 4.vii.1921, 1 ♂ (headless, genit. prep.), A. H. Sturtevant leg. (both USNM). OREGON: Curry Co., 8 mi N Gold Beach, 29.vi.1972, 1 ♂, G. Steyskal leg. (USNM, headless, genit. prep.). WASHINGTON: Whidbey Island nr. Keystone Ferry, 18.ix.1975, 1 ♀, G. F. Hevel leg. (USNM, genit. prep., legs and one wing missing).
Description. Male. Total body length 2.58–3.10 mm. Externally very similar to A. concolor including the (slightly less) variable body colour (Fig. 339), ranging from largely yellow to largely brown, although the latter variant seems to be comparatively infrequent. Head about as long as high or somewhat longer than high, anteriorly distinctly angular in pronle and face receding (more than in A. concolor), largely yellow but frons and particularly occiput with variable pale to dark brown markings. Occiput distinctly concave medially, in pale specimens light yellow with dark yellow to ochreous brown crescent-shaped areas surrounding the medial pair of silvery white microtomentose spots; in darker specimens these areas darker and widened laterally; in darkest specimens occiput largely brown to dark brown (including small spot behind ocellar triangle), with only medial area above foramen (= ground of silvery white microtomentose spots) yellow and connected dorsally with orbital stripes. Frons relatively narrow, largely dull, pale to dark yellow with only ocellar triangle brownish (lighter in pale specimens), in darkest adults also middle of frontal triangle (usually pale) brown and ocellar triangle blackish brown; frontal triangle subshining, with sparse whitish grey to white microtomentum (denser and nner on ocellar triangle). Orbits pale to whitish yellow with sparse silvery white microtomentum as in A. concolor. Frontal triangle narrower (posteriorly only slightly wider than ocellar triangle) and shorter than in A. concolor, reaching to anterior third of frons. Frontal lunule small, yellow. Face, parafacialia and gena formed, coloured and microtomentose as in A. concolor; postgena, ventral part of occiput and mouthparts pale yellow to yellow (also in darkest specimens). Cephalic chaetotaxy (all setae black) as in A. concolor but pvt usually (sometimes surprisingly) long and strongly crossed, no additional microsetula in front of shorter anterior ors setula; subvibrissa similar to foremost peristomal setula and peristomals (4–6) usually shorter. Palpus as in A. concolor, including chaetotaxy. Eye subovoid, broader anteroventrally, with longest diameter oblique and 1.5–1.6 times as long as shortest. Gena lower than in A. concolor, with shortest height 0.11–0.13 times as long as shortest eye diameter. Antenna geniculate, entirely yellow; 1st nagellomere with white pilosity somewhat longer than in A. concolor. Arista with basal segments ochreous to brown and distal setiform part blackish brown, the latter about 2.1 times as long as antenna, shortciliate (cilia somewhat shorter than those on 1st nagellomere).
Thorax hardly narrower than head. Scutum with variable colouration ranging from almost entirely yellow, through yellow with various brownish darkened areas (lateral stripes outside of dc lines, medial area in posterior half) to almost entirely dark brown (usually with paler brown notopleural area). Scutellum yellow, with various brown darkening medially to almost completely dark brown (often with paler margins). Dorsum of thorax with distinct yellowish grey microtomentum (best visible in darkest specimens) and relatively dull. Pleural part of thorax more shining than scutum, most often entirely yellow or with various brown markings (more dorsally) to largely dark brown with only small areas (usually ventrally) ochreous brown to yellow. Postscutellum (this always darker) and postnotum yellow to ochreous to dark brown. Thoracic chaetotaxy very similar to that of A. concolor but anterior dc longer than all other setae on scutum except for posterior dc (being longest thoracic seta) and hindmost dc microseta unusually enlarged and resembling a third dc macroseta (sometimes there is 1 additional, more anterior, enlarged dc microseta); sternopleuron with 4–6 upcurved setulae in dorsal half and with 4–5 longer setae ventrally. Scutellum rounded subtriangular, slightly to distinctly convex dorsally. Legs pale yellow to deep yellow (also in darkest specimens in contrast to A. concolor), only distal half to four-nfths of last tarsal segment of all tarsi dark brown. Pedal chaetotaxies as in A. concolor but f 1 with ctenidial spine as long as or slightly longer than maximum width of t 1 and f 3 with 6–9 (usually 8–9) shortened and thickened setae in posteroventral row. Wing (Fig. 337) extremely similar to that of A. concolor including venation but R 4+5 and M usually more distinctly bent and r-m often situated distinctly in front of middle of discal cell (dm). Wing measurements: length 2.79–3.38 mm, width 0.97–1.12 mm, Cs 3: Cs 4 = 0.97–1.12, rm\dm-cu: dm-cu = 2.15–2.61. Haltere yellowish white with slightly darker stem (as in A. concolor).
Abdomen also variable in colouration, although less so than in A. concolor. Colour of preabdominal terga (T1–T5) largely yellow to ochreous only in palest specimens and completely brown in darkest specimens, but in others with various darker markings: T1–T3 usually more darkened than T4–T5 or T1–T3 entirely brown and T4–T5 partly ochreous yellow. T1–T5 sparsely greyish microtomentose and subshining, with relatively short and sparse setae as in A. concolor. T1 and T2 dorsally distinctly separate but laterally fused. T1 shortest, T2 slightly shorter than T3–T4, the latter subequal in size; T5 slightly longer than T4, all terga bent onto lateroventral sides of abdomen. Preabdominal sterna pale yellow to ochreous, in dark specimens S1, S2 and S5 (this usually partly) brown darkened, all relatively broad and becoming slightly wider posteriorly; S1 as in A. concolor, S2 slightly wider than long, S3–S5 about 1.5 times wider than long; S3–S4 transversely suboblong, S5 not wider than S4 but with posterior margin slightly emarginate. S2–S5 nnely but not densely setose, S1 bare and with usual darker posterior stripe. T6 very short and transverse, bare, submembranous, pale yellow to ochreous brown but with only lateral parts pigmented (usually poorly visible). S6–S8 brown to dark brown, S8 darkest but usually paler than epandrium. S6 and S7 with darker anterior marginal ledge, S6 with 2–3, S7 with 2 relatively long setae; S8 about as long as epandrium, paler at anterior margin, setose in posterior half.
Genitalia. Epandrium (Figs 343, 344) uniformly brown to blackish brown, distinctly longer, of shorter height and particularly broader than in A. concolor, with sparser setae than in latter species, several (2–3 dorsolateral pairs) of them longer than others; anal nssure larger and wider than that of A. concolor, triangular (Fig. 343). Cerci more robust and more distant from each other (Fig. 343), with a number of nne setae, apical longest. Medandrium (Fig. 343) moderate and formed as in A. concolor but ventrally with deeper semicircular emargination. Gonostylus (Figs 343, 344, 349) distinctly different from that of A. concolor and other relatives, elongate but somewhat shorter than epandrial height, regularly bent medially, tapered towards an acutely pointed apex (Fig. 349), in lateral view with anterior margin distinctly convex (Fig. 344), micropubescent on most of outer side and with relatively long nne setae on concave inner side. Hypandrium (Fig. 345) similarly formed to that in A. concolor but more robust. Transandrium (Fig. 346) thicker than in A. concolor and distinctly arched dorsomedially, without distinct caudal process except for a (broadly set) pair of short sclerotizations transilient to spinose parts of basal membrane. Pregonite (Fig. 345) somewhat different from that of A. concolor, with anterior tooth acute and bent posteromedially, but small angled, tuberculate protuberance behind it lacking; posteriorly with usual narrow projection transilient to basal membrane; pregonite with 6–7 (one longer) setae ventrally. Postgonite (Fig. 345) nat, similar to that in A. concolor but having simple base attached to a distinct internal dorsal sclerite and 1 anterolateral seta situated near base. Basal membrane (Fig. 346) with spinose area wider and shorter than in A. concolor (darker spines laterally, pale and nat medially). Aedeagal part of folding apparatus laterally with a double row of very small dark tubercles (Fig. 348) as in A. concolor. Connecting sclerite strong and dark proximally, distally less sclerotized, lighter and with only small pale tubercles (without spines) (Fig. 348). Phallapodeme similar to that in A. concolor, including position of fulcrum, which is basally broader. Aedeagus (Fig. 348) also resembling that of A. concolor but saccus with different armature, base without nat ventral plate but with a weak lateral sclerotization partly ovelapping basal spine, and with only 4 robust dark-pigmented spines, 1 or 2 of which have bases dilated and sclerotized. Filum also most similar to that of A. concolor but having only small spines (instead of one robust tooth-like process) in front of terminal slender part, and its curved apex (with bicuspid tip) provided with more (up to 10) small spines (Fig. 347). Ejacapodeme small, pale, with thicker but short terminal end (Fig. 348).
Female. Similar to male unless mentioned otherwise. Total body length 3.01–3.77 mm. Head, thorax and preabdomen with similar colour variations to those in male, but dark specimens rarer and lightest specimens with darkenings on occiput and mesonotum very faded to absent. Antenna with 1st nagellomere ochreous to brownish darkened on anterodorsal half of outer side; inner side of 1st nagellomere sometimes (also in pale specimens) similarly or less infuscated. f 1 with ctenidial spine as in male but f 3 lacking posteroventral row of shortened and thickened setae. Wing measurements: length 3.43–4.01 mm, width 1.15–1.39 mm, Cs 3: Cs 4 = 0.98–1.18, rm\dm-cu: dm-cu = 2.08–2.67. Abdomen with T1–T6 of variable colouration, ranging from entirely yellow, through partly brown to entirely brown. T1–T5 somewhat shorter and more transverse than in male. T1 distinctly, T2 slightly narrower than T3, T3–T5 widest and subequal in size or T5 slightly longer. Preabdominal sterna whitish yellow to ochreous, not narrower than in male, S3–S5 becoming only slightly wider posteriorly. S2 distinctly transverse, about 1.5 times as long as wide and usually darker (or with central brownish spot) than other sterna (except for the usual dark posterior stripe of S1), S3–S5 distinctly suboblong, up to twice as long as wide. All S2–S5 densely nnely setose.
Postabdomen (Figs 351, 352, 377) somewhat shorter and wider than in A. concolor, telescopic. T6 large, longer and narrower than in A. concolor, slightly tapered posteriorly and with posterior corners broadly rounded, yellow and (often) with central brown spot of various extent or completely brown, with relatively short and dense setae in posterior two-thirds, marginal setae longest. S6 transversely suboblong to trapezoidal with anterior corners rounded, also longer than in A. concolor, pale yellow to pale ochreous and (in contrast to A. concolor) densely setose. Tergosternum T7+S7 moderately long, slightly tapered posteriorly, dorsomedially less shortened (not incised anteromedially) than in A. concolor, ventrally shorter and with simple anterior margin. T7+S7 variable in colour, yellow with large brown dorsal spot (Fig. 351) in pale specimens to completely dark brown (also ventrally brown) in darkest specimens. T7+S7 ventrally less convex than in A. concolor, with lateral margins of original S7 relatively straight (Fig. 377) and separated from T7 by wider membranous slit almost reaching to anterior margin of synsclerite with 7th spiracle embedded in T7 close to this slit (Figs 352, 377). Dorsal part of T7+S7 (Fig. 351) with dense, nne and longer setae (in contrast to A. concolor); ventral part nnely setose. 8th segment with nnely densely micropubescent membrane laterally. T8 (Fig. 351) wider than in A. concolor, slightly longer than wide, bent onto sides, brownish, with deep anteromedial emargination and posteromedially with pale-pigmented semicircular area, sparsely setose, and without micropubescence; S8 (Fig. 352) slightly shorter than T8, subcordate and medially divided as in A. concolor. Genital chamber (uterus) posteriorly with pigmented internal sclerotization (Figs 353, 356) composed of only 1 pair of nat crooked sclerites (medially more separated than those of A. concolor, cf. Fig. 353 versus Fig. 332) and 1 subcircular, curved (in pronle) annular sclerite situated anteroventrally to the former. Membranous part of genital chamber long, as in A. concolor, without additional small sclerotizations. Ventral receptacle (Fig. 355) very slender and long, tubular and hyaline, with coiled vermicular apex, thus resembling that of A. concolor. Accessory gland small, vesicular, hyaline, on distally slightly dilated but indistinctly ringed duct. Spermathecae (1+1) shortly ovoid with somewhat nattened distal end (Figs 350, 354); with deep invagination (distinctly broader than in A. concolor) which may be partially everted, and with several small tubercular (not pointed) spines in basal part; duct very long and ending without obvious cervix centrally in spermathecal body. T10 pale brown, small and shorter than long (Fig. 351), rounded and wider posteriorly and emarginate anteriorly, with 3–5 pairs of setae (1 long) and reduced micropubescence. S10 yellowish, larger and wider than T10, pentagonal in ventral view (Fig. 352), nnely setulose and micropubescent. Cercus moderately short, slightly wider than in A. concolor, with nne and relatively short setae, apical and dorsopreapical longest (Figs 351, 352).
Discussion. Anthomyza occidentalis sp. nov. is one of the largest representatives of the genus and is supported as being closely allied to A. concolor, externally resembling this species in numerous aspects including large body size and striking colour variability. Structures of the male genitalia are especially supportive of a sister-species relationship, having a similarly formed fulcrum of the phallapodeme, similar armature of the basal membrane and aedeagal part of folding apparatus, and similar construction and armature of the saccus and nlum of the aedeagus. The short, narrow frontal triangle is one of a few external features distinguishing A. occidentalis from A. concolor, but the genitalia of both sexes provide a number of often small differences useful for diagnosis. For the A. occidentalis male: epandrium broad, gonostylus pointed and differently curved, pregonite without small tuberculate angle behind anterior tooth and with more setae, postgonite with basally situated seta, basal membrane with spinose area broad and short, saccus with only 4 spines and some with expanded bases, nlum without subterminal tooth but with more small spines on apex, and connecting sclerite without spines apically. For the A. occidentalis female: T6 and S6 both longer and narrower, dorsal part of T7+S7 without anterior emargination or long nne setosity, ventral part of T7+S7 less convex and S7 component shorter and more separated from T7, 7th spiracle close to margin of T7, T8 shorter, internal sclerotization of the genital chamber with only 1 pair of more separated posterior sclerites, spermathecae with wider invagination and spines reduced to blunt tubercles, and T10 short and transverse.
Etymology. The name of this new species refers to its strictly western distribution; Latin adjective occidentalis meaning western.
Biology. The type locality (Oregon: Tokatee Klootchman State Natural Site, Fig. 314) contained a relatively narrow patch of Equisetum telmateia braunii and an unidentined species of Angelica at the base of a coastal cliff; the latter species is unlikely to serve as a host for A. occidentalis. The central role of E. telmateia braunii as a host plant is further implicated in two other separate collections (California: Cambria; Oregon: Samuel Boardman St. Pk.). The Cambria site had a very simplined vegetative cover with only the horsetail and the introduced invasive ivy, Delairea odorata Lemaire, present under a forest canopy. The most productive subsite at the open coastal hillside of Samuel Boardman State Park supported a more complex community including a grass component but the horsetail was still dominant. The distribution of A. occidentalis also very closely tracks the distribution of E. telmateia braunii, as documented by HAUKE (1993), but see comments under Distribution.Another fairly specinc observation was made of a riparian Scirpus sp. (California: Prairie Ck. Redwoods S. P. – Elk Prairie Campground) where E. telmateia braunii was not observed but this needs connrmation as it is based on a single male of A. occidentalis. There are additional less specinc habitat references such as “fen area” (California: Inglenook Fen), “ willow thicket” (California: San Francisco, Lake Merced), and “bog area” (California: McKinleyville). Anthomyza occidentalis has been taken at sites also yielding A. concolor (California: Cambria, Rosemead), A. vockerothi (California: Pt. Reyes) or both these species (Oregon: Samuel Boardman St. Pk.) but the collections at the last two sites were dominated by A. vockerothi. Anthomyza occidentalis and A. concolor would represent the third and fourth species of Anthomyza to be associated with a horsetail (see discussions under A. equiseti and A. vockerothi), possibly exclusively for A. occidentalis as in A. equiseti. The known night period for A. occidentalis runs from 17 March (California: Rosemead) to 18 September (Washington: Whidbey Island).
Distribution. Anthomyza occidentalis has, by far, the most restricted distribution of all the Nearctic Anthomyza. In Canada it is known only from southern British Columbia (Milner, single female) and in the United States of America from the three west coast states of Washington, Oregon and California (see Table 2, Fig. 600). As mentioned above, this distribution may well be constrained by the range of E. telmateia braunii, but this horsetail reaches as far north as southeastern Alaska (HAUKE 1993), which is well beyond the current northern record for A. occidentalis.
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 201-210, DOI: 10.5281/zenodo.4272829