Chimerothalassius ismayi Shamshev & Grootaert, 2003

Brooks, Scott E. & Cumming, Jeffrey M., 2022, New Australasian Parathalassiinae (Diptera: Dolichopodidae sensu lato), Zootaxa 5188 (6), pp. 521-543 : 524

Chimerothalassius ismayi Shamshev & Grootaert

( Figs 3, 4 , 12, 13 )

Chimerothalassius ismayi Shamshev & Grootaert, 2002: 133 . Type locality: South Birdlings Flat , New Zealand.

Material Examined. NEW ZEALAND: North Island, Waikato Region, Stony Bay , 36°30ʹ42.3ʺS 175°25ʹ24.4ʺE, steep short bay with river outlet, beach with mix of large pebbles & sand, 12.iv.2019, R . J. Le Grice (1♀, NZAC, photo); North Island, Wellington Region, Ôwhiro Bay , 41°20ʹ40.8ʺS 174°45ʹ32.2ʺE, 11.xii.2019, small steep enclosed bay with freshwater stream outlet, beach with mix of medium and small stones, R . J. Le Grice (1♀, NZAC, photo); South Island, Banks Pen., Port Levy [ca 43°39ʹS 172°48ʹE], 22–26.ii.1999, near sea streambed, pan traps, S.A. Marshall, debu00102042 (1♂, DEBU); South Island , NN [Nelson area code], Cable Bay , 41°09.6ʹS 173°24.9ʹE, 13.ii.1998, W.N. Mathis, USNM ENT 00085568 (1♀, USNM) .

Diagnosis. Males of C. ismayi are distinguished from the other known Australasian species of the genus by their elongate yellow palpus ( Fig. 12 ), grey body, yellow legs and several hypopygial features ( Shamshev & Grootaert 2002, figs 18–22) including: left ventral epandrial process with tip weakly bent; left ventral surstylus relatively short with short setae; right ventral epandrial process straight; phallus with funnel-like tip; hypoproct simple and narrow. Females of C. ismayi (see “Remarks” below) are distinguished by the following features: fore femur with row of 4–5 long spine-like ventral setae on basal half ( Fig. 13 ); palpus elongate and brownish with 3 long spine-like ventral setae (about 2X palpus width); terminalia with syntergite 9+10 undivided and bearing acanthophorous setae, cercus narrowly rounded apically with prominent preapical seta ( Shamshev & Grootaert 2002, figs 23–25).

Distribution. Chimerothalassius ismayi is known only from New Zealand and has been collected at Ôwhiro Bay and Stony Bay on North Island, and Cable Bay, Port Levy and South Birdlings Flat [ca 43°49ʹS 172°42ʹE] on the northern part of South Island ( Figs 3–7 ).

Remarks. The type series from South Birdlings Flat and the female specimens from Ôwhiro Bay and Stony Bay were swept or hand collected from stony beaches (e.g., Fig. 4 ) or beaches with mixed pebbles and sand, while the Port Levy male specimen was taken in a pan trap along a stream bed near the sea ( Fig. 6 ). Shamshev & Grootaert (2002) noted great sexual dimorphism in the chaetotaxy of the palpus and foreleg of C. ismayi , which is not seen in C. runyoni Brooks & Cumming from the Caribbean ( Brooks & Cumming 2018), or C. riparius sp. nov. from New Caledonia, described below. Although we have not seen the type series of C. ismayi (8 males and 14 females from South Birdlings Flat, South Island deposited in the Royal Belgian Institute of Natural Sciences, Brussels, Belgium), we have examined a male collected from the nearby locality of Port Levy (DEBU), and females collected from Cable Bay (USNM), Ôwhiro Bay and Stony Bay (NZAC) that are virtually identical to the male holotype, male paratypes and female paratypes illustrated and described by Shamshev & Grootaert (2002, figs 1–26). Given the major differences in the chaetotaxy of the palpus and foreleg between the males and females of the type series (as well as the male and females we examined), we suspect that the female paratypes of C. ismayi and the females from Cable Bay, Ôwhiro Bay and Stony Bay actually belong to an undescribed species for which the male remains undiscovered. Even though the type specimens of C. ismayi were all collected from a single stony beach on the same day, multiple species of certain parathalassiine shoreline genera, such as Amphithalassius Ulrich , Parathalassius Mik , and Plesiothalassius Ulrich are known to co-inhabit single beaches ( Ulrich 1991; Brooks & Cumming 2017). The same appears true for Chimerothalassius , at least at the Port Levy locality, where both C. ismayi and C. marshalli sp. nov. were taken during the same collecting event. The female specimens currently assigned to C. ismayi also do not appear to be conspecific with C. marshalli sp. nov. based on differences in chaetotaxy of the palpus, gena, thorax and foreleg.

Figures

FIGURES 1–4. Known geographical distribution and collection localities of Microphorella and Chimerothalassius from Australia and New Zealand. 1. Distribution of M. bungle sp. nov., M. iota Colless and M. viticula sp. nov. 2. Govetts Leap,Australia, type locality of M. viticula sp. nov. (photo by Brad Sinclair). 3. Distribution of C. ismayi Shamshev & Grootaert, C. marshalli sp. nov., Chimerothalassius sp. 1 (female from Takapuna Beach) and “Chimerothalassius” sp. 2 (female from Three Kings Is.). 4. Birdlings Flat, New Zealand, type locality of C. ismayi Shamshev & Grootaert (photo by Rebecca Le Grice).

FIGURES 12–15. Chimerothalassius ismayi Shamshev & Grootaert and C. marshalli sp. nov. 12. Male of C. ismayi Shamshev & Grootaert from Port Levy, New Zealand (debu00102042), left lateral view. 13. Female of C. ismayi Shamshev & Grootaert from Cable Bay, New Zealand (USNM ENT 00085568), head and foreleg. 14. Male holotype of C. marshalli sp. nov., left lateral view of head and thorax. 15. Male holotype of C. marshalli sp. nov., dorsal view of head and thorax. Abbreviation: plp—palpus.

FIGURES 5–7. Port Levy, New Zealand, type locality of Chimerothalassius marshalli sp. nov. (photos by Morgane Merien).