Parathalassius socali, Cumming, 2017

Cumming, Jeffrey M., 2017, Revision of the Nearctic Parathalassius Mik (Diptera: Dolichopodidae: Parathalassiinae), with a review of the world fauna, Zootaxa 4314 (1), pp. 1-64: 35-42

publication ID

publication LSID

persistent identifier

treatment provided by


scientific name

Parathalassius socali

sp. nov.

Parathalassius socali   sp. nov.

( Figs 34 View FIGURES 29 – 37 , 45 View FIGURES 38 – 47 , 65 View FIGURES 56 – 67 , 89–90 View FIGURES 80 – 94 , 107–108 View FIGURES 103 – 110 , 123 View FIGURES 121 – 126 , 139 View FIGURES 133 – 141 , 150 View FIGURES 148 – 150 )

Type material. HOLOTYPE ♂ labelled “ USA: CA: Orange Co., San / Clemente SB [State Beach], 33°24′18.7″N / 117°36′22.8″W,,/ swp [swept] sandy seacoast, J.M. / Cumming, CNC577380 View Materials ”; “ HOLOTYPE / Parathalassius socali   / Brooks & Cumming [red label]” ( CNC) GoogleMaps  

PARATYPES: USA: California: same data as holotype except, CNC577343, CNC577346, CNC577347, CNC577348, CNC577354–CNC577356, CNC577362, CNC577366, CNC577377, CNC577383, CNC577396, CNC577398, (13♂, CNC) GoogleMaps   ; same data as holotype except, CNC577376 View Materials , CNC577390 View Materials (2♂, barcoded, CNC) GoogleMaps   ; same data as holotype except, CNC577331, CNC577337, CNC577340, CNC577345, CNC577349, CNC577350– CNC577353, CNC577357 CNC577361, CNC577363, CNC577364, CNC577367–CNC577369, CNC577371 CNC577379, CNC577381, CNC577382, CNC577384, CNC577386, CNC577391– CNC577395, CNC577397, CNC577399, CNC577401, CNC580706 (39♀, CNC) GoogleMaps   ; same data as holotype except, CNC577344 View Materials , CNC577385 View Materials , CNC577389 View Materials (3♀, barcode-associated, CNC) GoogleMaps   ; same data as holotype except, S.E. Brooks, CNC574853 View Materials , CNC574856 View Materials , CNC574858 View Materials , CNC574863 View Materials (4♂, CNC) GoogleMaps   ; same data except, CNC574860 View Materials (1♂, barcoded, CNC) GoogleMaps   ; same data except, CNC574855, CNC574857, CNC574859, CNC574861, CNC574864, CNC574865, CNC574868– CNC574871 (10♀, CNC) GoogleMaps   ; same data as holotype except, S.H. Cumming, CNC577405 View Materials (1♂, CNC), CNC577402 View Materials , CNC577404 View Materials (2♀, CNC) GoogleMaps   .

Other material examined. USA: California: Monterey County: Salinas River State Beach [ca. 36°46′33″N 121°47′50″W], 26.vii.1994, dunes, H. Ulrich (16♂, 2♀, ZFMK) GoogleMaps   ; same data except, 27.vii.1994 (13♂, 26♀, ZFMK) GoogleMaps   ; Orange County: Huntington Beach [ca. 33°39′27″N 118°00′25″W],, A.L. Melander (1♂, USNM) GoogleMaps   ; San Clemente ,, A.L. Melander (8♂, 1♀, USNM)   ; Santa Barbara County: Carpinteria [ca. 34°23′35″N 119°31′29″W],, A.L. Melander (2♂, 2♀, USNM) GoogleMaps   ; same data except, (9♂, 1♀, USNM) GoogleMaps   ; same data except, (3♂, 1♀, USNM) GoogleMaps   ; Surf Beach, Vandenberg Air Force Base, 34.683801°N 120.605520°W,, J.M. Cumming, ex: Ambrosia chamissionis   & coastal dunes (1♀, CNC); same data except CNC582795 View Materials , CNC582813 View Materials (2♀, barcode-associated, CNC) GoogleMaps   .

Diagnosis. This relatively small species is characterized by a short-subtriangular antennal postpedicel, longer lower male ommatrichia, 2 notopleural bristles, hyaline wing, relatively dark legs, male hind tarsomere 1 with long erect setae dorsally, male hypopygium compact, and female sternite 8 with apical longitudinal ridges at most barely developed laterally.

Description. Male: Body length 1.9–2.3 mm, wing length 1.6–1.7 mm. Dark brown ground colour covered mostly with dense greyish-white pruinosity. Setae of body and legs white. Head ( Fig. 34 View FIGURES 29 – 37 ): Eyes with ommatrichia of lower third distinctly longer and slightly flattened, forming dense reflective mat of whitish coloured hair. Face and clypeus concolourous with greyish-white frons and vertex. Face narrowest at middle, about 2.0–2.75X width of anterior ocellus. Gena and postgena with moderately long white setae, forming short beard flanking mouthparts. Antenna ( Fig. 45 View FIGURES 38 – 47 ) brown to dark brown, arista-like stylus lighter in colour in most specimens; postpedicel shortsubtriangular, 1.25–1.4X longer than wide; arista-like stylus of medium length, about 1.6X length of postpedicel. Palpus with 7–8 setae on outer surface of apical half. Thorax: Acrostichal setulae primarily biserial; 6–7 dorsocentral bristles, 0 presutural intra-alar bristles, 1 presutural supra-alar (posthumeral) bristle, 2–3 postsutural supra-alar bristles, 2 notopleural bristles. Scutellum with 2 pairs of bristles. Legs: Foreleg: Dark grey, pale at knee and apex of tibia, tarsomere 1 pale yellow basally, apex of tarsomere 1 and tarsomeres 2–5 greyish-brown. Coxa with moderately long pale setae on anterior surface. Femur with mostly short setae on posterior surface, posterodorsal row long. Tibia with short setae and setulae. Tarsus with setulae; tarsomeres 1–2 not dilated. Midleg: Dark grey, pale at knee and extreme apex of tibia, tarsomere 1 pale yellowish-brown, tarsomeres 2–5 brown to greyish-brown. Femur with anterodorsal setae most prominent, short. Tibia with 1 apicoventral bristle. Tarsomeres 1–4 each with several dark spine-like apicoventral setae. Hindleg: Dark grey, femur dark brown posteriorly, pale at knee, tarsomere 1 pale yellowish-brown (apex brown in some specimens), tarsomeres 2–5 brown to greyish-brown. Femur with anteroventral row of setae most prominent, short basally, longer apically. Tibia with anterodorsal and anteroventral rows of setae long, mostly longer than width of tibia, anterodorsal row longest. Tarsus slightly longer than tibia with mostly short setae and setulae; tarsomere 1 shorter than combined length of tarsomeres 2–4, bearing long erect setae dorsally; tarsomeres 1–4 lacking peg-like or thickened setae dorsally; tarsomere 2 distinctly longer than tarsomere 3; tarsomere 3 longer than tarsomere 4; tarsomere 5 subequal in length to tarsomere 3. Wing ( Fig. 65 View FIGURES 56 – 67 ): Hyaline with yellowish brown veins. Cell dm produced apically, dm-m crossvein slightly concave. Vein CuA+CuP short to medium length, slightly curved to straight. Abdomen: Tergites 2–4 with setae well-developed. Sternite 5 with small nub-like pregenitalic process present, posterior edge of sternite 5 (behind process) weakly emarginate. Sternite 8 subquadrate with setae longer along posterolateral margins. Hypopygium ( Figs 89–90 View FIGURES 80 – 94 , 107– 108 View FIGURES 103 – 110 , 123 View FIGURES 121 – 126 ): Relatively compact. Left epandrial lamella with ventral portion elongate (about 2X longer than high); ventral epandrial process broadly bifurcate, dorsal arm with weak ventral curve, apex expanded and blunt, ventral arm thick with minute apicodorsal seta and pair of minute setae along distiventral margin, apex with expanded lamelliform concavity. Dorsal lobe of left surstylus with basiventral edge rounded and flap-like, apex broadly rounded, with long basidorsal seta on bump-like protuberance, short lateral seta and long apical seta, medial surface with stalk-like projection bearing lamelliform apical seta. Ventral lobe of left surstylus bilobate, dorsal lobe short with apex subquadrate, ventral lobe with basal pointed process bearing apical seta and complex upturned bifurcate projection arising medioventrally. Right epandrial lamella with ventral epandrial process barely developed as short angular projection; basal portion of epandrial lamella narrowed and dorsally curved, with deep dorsal emargination bordering ventral margin of right cercus. Dorsal lobe of right surstylus with 3 lateral setae (distal-most seta stronger), apex narrowed with subtriangular tip bearing thick apically-frayed prensiseta on medial surface. Ventral lobe of right surstylus with lateral seta at basal third and 2 slightly shorter setae below, distal 2/3 recurved, slender with narrow apically pointed lamelliform seta proximal to rounded lamelliform apex. Hypandrium large, reniform and bare. Left postgonite lobe ovoid basally, constricted near middle, distal portion subrectangular and flat without claw-like apical process, base of lobe with broad curved apically-pointed medial projection. Right postgonite lobe with broad lateral protuberance and lamelliform medial projection, apex bifurcate with well-developed digitiform ventral process and lamellate dorsal process. Phallus relatively short and moderately curved, flattened preapically with membranous region on right side, apex bent laterally. Ejaculatory apodeme subtriangular with apex slightly curved ventrally. Hypoproct projected dorsally as pair of slender pointed lobes, each lobe with ventral cluster of 3–4 minute setae proximal to apex. Cerci with anal setae well-developed and differentiated from surrounding hairs; right cercus much larger than left cercus with basal portion distended and rounded laterally, apex slightly widened, not dorsally deflected, truncate with pair of setae at apicolateral margin; left cercus oblong-subrectangular in dorsal view, apex even with apex of right cercus, not dorsally deflected, acute with pair of thickened apical setae.

Female: Body length 2.3–3.0 mm, wing length 2.0– 2.2 mm. Similar to male except as follows: Head: Eyes with ommatrichia of nearly uniform length, not distinctly longer on lower third. Face wider, at middle about 4.0– 4.25X width of anterior ocellus. Legs: Hindleg: Tibia with anterodorsal and anteroventral rows of setae slightly shorter. Tarsomere 1 without erect setae dorsally. Abdomen: Tergite 5 broadly subtriangular to semicircular in dorsal view with posterior margin rounded (cf. Fig. 131 View FIGURES 127 – 132 ). Terminalia distinctly narrower than base of segment 5 (cf. Figs 131–132 View FIGURES 127 – 132 ); sternite 8 trough-like, with weak basal bulge, not narrowed apically, apical half with longitudinal ridges absent to barely apparent, at most slightly developed laterally along apical margin and not present medially, apex emarginate ( Fig. 139 View FIGURES 133 – 141 ); sternite 9 unsclerotized and indistinct; tergite 10 with hemitergites subtriangular and short, each with 2 acanthophorite spines; cercus short, pointed apically.

Distribution and seasonal occurrence. Parathalassius socali   is currently known only from sandy seashores in southern California, from Salinas River State Beach in Monterey County, south to San Clemente in Orange County ( Fig. 150 View FIGURES 148 – 150 ). Adults have been collected from early June to late July.

Etymology. The specific name refers to the southern Californian distribution of this species and is derived from the commonly used abbreviation, SoCal.

Remarks. The COI barcode sequence data obtained from specimens of P. socali   ( Fig. 154 View FIGURE 154 ) indicate a significant degree of genetic divergence (at minimally 3.5%) between populations at Surf Beach, Santa Barbara County (represented only by females) and San Clemente, Orange County. This suggests considerable isolation of populations of this species on these two geographically distant beaches (380 km apart).


Canadian National Collection of Insects, Arachnids, and Nematodes


Zoologisches Forschungsmuseum Alexander Koenig


Smithsonian Institution, National Museum of Natural History


University of Coimbra Botany Department