Chimerothalassius marshalli Brooks & Cumming 2022, sp. nov.
Creators: name: Brooks, Scott E.
name: Cumming, Jeffrey M.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Chimerothalassius
Chimerothalassius marshalli

description: Chimerothalassius marshalli sp. nov.
(Figs 3, 5–7, 14–18)
urn:lsid:zoobank.org:act: DF9EEF18-DC3F-4A79-B56D-31D56900769E
Type material. HOLOTYPE ♂ labelled: “ NZ. South Is., Banks / Pen., Port Levy [ca 43°39ʹS 172°48ʹE], 22–26/ Feb 1999, near sea/ streambed, pan traps,/ S.A. Marshall,/ debu00102014”; “ HOLOTYPE / Chimerothalassius marshalli / Brooks & Cumming [red label]” (NZAC).
Additional material. NEW ZEALAND: South Island, Canterbury Region, Sumner Beach, 43°34ʹ16.1ʺS 172°45ʹ55.1ʺE, sandy exposed flat beach with large rock seawall and freshwater outlet, 16.xi.2018, R. J. Le Grice (1♂, NZAC, photo).
Diagnosis. Known only from males, C. marshalli sp. nov. is distinguished from the other known Australasian species of the genus by its elongate dark brown palpus (Fig. 14), dark brown body and legs (Figs 14, 15), strong dark genal setae and several hypopygial features (Figs 16–18) including: left ventral epandrial process with hook-like tip; left ventral surstylus relatively short with several strong ventral setae; right ventral epandrial process straight; phallus with tip not expanded and with pointed process near midlength; hypoproct simple and narrow.
Description. Male (Figs 14–18): Wing length approximately 1.40 mm. Head (Figs 14, 15): Dark brown-grey pruinose, with bronze and weak greenish reflections; slightly broader than thorax in dorsal view; round in lateral view (about as broad as high); broader than high in anterior view; larger setae black. Ocellar triangle conspicuous. Occiput concave on upper median part. Eyes covered with short ommatrichia; medial edge of eye with distinct emargination adjacent to antenna; ommatidia progressively smaller anterodorsally. Frons 1.6X broader than high, subtriangular, widening above. Face narrow, with eyes nearly contiguous. Face and clypeus concolorous with rest of head. Clypeus not separated from face, small and triangular, not produced. Setae of head well differentiated: 1 pair of lateroclinate fronto-orbitals close to base of antennae; 1 pair of lateroclinate anterior ocellars; 2 pairs of small posterior ocellars; 1 pair of strong inclinate inner verticals (sometimes referred to as postocellars); 2 pairs of lateroclinate outer verticals; postoculars short and uniserial, lower setae fine and pale. Antenna entirely dark brown, inserted near middle of head in profile; scape short, funnel-shaped; pedicel subequal in length to scape, spheroidal with subapical circlet of setulae; postpedicel 2X longer than wide, bulb-shaped with basal half round and distal half narrow, clothed in fine setulae; arista-like stylus 1.5X length of postpedicel, with minute hairs (right postpedicel of holotype deformed and elongated, with very short deformed stylus). Palpus dark brown, elongate and gradually enlarged apically, with preapical ventral seta. Proboscis dark brown, short. Gena narrow, with several strong dark setae surrounding oral cavity. Thorax (Figs 14, 15): Dark brown-grey pruinose, with bronze and weak greenish reflections especially dorsally, setae black. Mesoscutum moderately arched, prescutellar depression present. Proepisternum with minute seta. Postpronotal lobe with minute seta. Mesonotum longer than wide. Acrostichal setae absent; other thoracic setae well differentiated, each side of mesonotum with: 4 dorsocentrals, 1 presutural supra-alar (posthumeral), 1 postsutural supra-alar, 2 notopleurals, 1 postalar. Scutellum broadly subtriangular with 1 long, strong, dorsally projected seta per side. Mesopleuron bare. Halter pale brown. Legs: Evenly brown; with mostly short setae; tarsomeres 1–4 of all legs progressively shorter apically with tarsomere 5 slightly longer than 4; tarsomere 5 of all legs with dorsomedial finger-like process; tarsal claws and pulvilli normally developed on all legs (empodium not observable on available specimens). Foreleg: Coxa with short, sparse pale setae on anterior surface, apical margin with setae longer; femur subequal in length to tibia; tarsus slightly longer than tibia; tarsomere 1 subequal to combined length of tarsomeres 2–5. Midleg: Coxa with 4 pale setae; femur, tibia and tarsus subequal in length; tibia with relatively strong black preapical ventral seta; tarsomere 1 subequal to combined length of tarsomeres 2–5. Hindleg: Coxa with 2 pale setae on lateral surface; femur subequal in length to tibia; tarsus slightly shorter than tibia; tarsomere 1 slightly longer than tarsomere 2. Wing: Similar to C. riparius sp. nov. (see Fig. 22), except as follows: R 1 terminating closer to middle of wing. Abdomen: Dark greyish-brown with small dark setae (weaker and pale on sternites); sternite 6 and segment 7 bare. Segments 5–7 narrowed and laterally compressed to form cavity on right side for hypopygium. Sternite 5 lacking pregenitalic process. Sternite 8 ovoid, with short setae; tergite 8 indistinct. Hypopygium (Figs 16–18): Concolorous with pregenitalic abdominal sclerites; lateroflexed to right; inverted with posterior end directed anteriorly; small and compact, about 1/4 length of abdomen; asymmetrical; foramen not formed. Epandrium divided into left and right lamellae. Left epandrial lamella (Fig. 16) partially overlapping left side of hypandrium, posterior margin trifurcate, ventrally fused with hypandrium but margin distinct; ventral epandrial process apparently articulated at base, long and slender with slight upward bend, tip hook-like and bent ventrally. Left surstylus bilobed, dorsal and ventral lobes separated by U-shaped cleft through which left postgonite lobe protrudes. Dorsal lobe of left surstylus with long apical seta, shorter dorsal seta and short preapical medial seta, lacking prensiseta. Ventral lobe of left surstylus as long as dorsal lobe with several elongate and strong ventral setae. Right epandrial lamella (Fig. 17) partially overlapping right side of hypandrium, ventrally fused with hypandrium but margin distinct, similar in length to hypandrium, with prominent seta near middle of posterior margin; ventral epandrial process present, narrow, straight and dorsally projected with pointed tip. Right surstylus bilobed, dorsal and ventral lobes separated by U-shaped cleft through which right postgonite lobe protrudes. Dorsal lobe of right surstylus relatively short with medially projected apical seta, long preapical dorsal seta and shorter dorsal seta, lacking prensiseta. Ventral lobe of right surstylus about 2X longer than dorsal lobe, with 1 ventral seta near base, 1 medial seta near middle and short apical seta. Hypandrium bowl-shaped, about as long as epandrium in lateral view. Left postgonite lobe large, apically bilobate, with thumb-like dorsomedial lobe and longer ventral lobe (Fig. 16). Right postgonite lobe shorter than left lobe, apically bilobate with ventral lobe as long as dorsomedial lobe and pointed medially (Fig. 17). Phallus tubular, J-shaped, projected dorsally, with pointed process near middle, with tip not expanded. Ejaculatory apodeme keel-like. Hypoproct simple and relatively narrow in dorsal view (Fig. 18), left and right sides symmetrical. Cercus subtriangular in dorsal view (Fig. 18) with projected apex bearing seta, with 3 prominent dorsal setae, left and right cercus symmetrical.
Female. Unknown.
Distribution. This new species is known only from the type locality of Port Levy and the nearby locality of Sumner Beach, near Christchurch, South Island, New Zealand (Figs 3, 5–7).
Etymology. This species is named in honour of our colleague, Dr. Stephen A. Marshall of the University of Guelph, who collected the holotype of this new species, as well as other valuable shoreline empidoid specimens.
Remarks. The holotype male was collected in a pan trap along a stream bed near the sea (Figs 5–7) and the male from Sumner Beach was hand collected on a sandy exposed flat beach.
description: Published as part of Brooks, Scott E. & Cumming, Jeffrey M., 2022, New Australasian Parathalassiinae (Diptera: Dolichopodidae sensu lato), pp. 521-543 in Zootaxa 5188 (6) on pages 526-527, DOI: 10.11646/zootaxa.5188.6.2, http://zenodo.org/record/7103618