Microphorella acroptera

Brooks, Scott E. & Cumming, Jeffrey M., 2025, Revision of the Microphorella acroptera species group and establishment of the Microphorella arcana species group (Diptera: Dolichopodidae sensu lato: Parathalassiinae), Zootaxa 5661 (4), pp. 451-503 : 452-454

Microphorella acroptera species group

Diagnosis. The Microphorella acroptera species group can be distinguished from other Nearctic Microphorella species groups by the following suite of characters: clypeus separated from face by suture (except in M. maculata sp. nov.); mouthparts with sensory pit on palpus (sometimes difficult to see in non-macerated specimens); male hind trochanter with tubercle bearing spine-like seta ( Figs 8, 9 , 18, 21, 24 , 48, 51 , 66 , 73, 77 , 93, 94 ; very small in M. maculata sp. nov.); male hind femur without patch of fine setae on posterior surface; wing with moderately long R 1 vein that usually terminates beyond midpoint of wing ( Figs 4 , 17 , 47 , 88, 89 , close to midpoint of wing in some specimens, Fig. 95 ); male abdominal sternite 5 with broad ventral projection ( Figs 10 , 46 , 49–51 , 66 , 70 ); hypopygium ( Figs 11–14 , 25–31 , 36–40 , 41–45 , 52–55 , 67–69 , 78–85 , 90, 91 , 97–99 ) with ventral edge of epandrium fused to hypandrium, but with margin mostly defined (margin partially indistinguishable in M. maculata sp. nov.); right epandrial lamella without ventral epandrial process; hypandrium bare; female abdomen (not known for M. convoluta sp. nov., M. maculata sp. nov., M. subacroptera sp. nov. and M. trochanterata sp. nov.) with tergite 5 usually bearing a cluster of stout medial setae ( Fig. 20 ), tergite 6 with setae on posterior margin unmodified (i.e., not forming prominent row of long, stout setae), syntergite 9+10 with acanthophorous spines and cercus narrow and pointed.

Distribution. The M. acroptera species group is known to occur from southeastern Alberta and northeastern Montana south to Washington, western Oregon and southern California, east to southwestern Nevada and northwestern Arizona ( Figs 100–105 ). The majority of records are from California.

Remarks. The M. acroptera species group is a morphologically heterogeneous assemblage but is considered to be monophyletic based on the possession of a tubercle on the hind trochanter of males ( Cumming & Brooks 2019). The species group comprises four distinct lineages, which are characterized below. Members of this species group are rarely collected, particularly in long series and are relatively scarce in collections. Adults have been taken in various riparian habitats, from moist temperate rainforests to desert oasis habitats ( Figs 1–3 ).

Included species. This group includes the following 16 described species: M. acroptera Melander , M. acuminata sp. nov., M. bifida sp. nov., M. compacta sp. nov., M. convoluta sp. nov., M. cornuta sp. nov., M. elongata sp. nov., M. maculata sp. nov., M. paracroptera sp. nov., M. serpentina sp. nov., M. sinuosa sp. nov., M. subacroptera sp. nov., M. tenuis sp. nov., M. triangulata sp. nov., M. trochanterata sp. nov. and M. tubifera Melander. One additional species is known ( Microphorella sp. A , see below), but is not formally named and described on account of the poor condition of the unique male specimen.

Figures

FIGURES 6–10. Male habitus, hindleg and abdomen of Microphorella acroptera Melander. 6. Habitus (Floras Creek, Oregon, CNC DIPTERA # 105201). 7. Abdomen of same specimen, right lateral view. 8. Hindleg of paratype, posterior view, arrow indicating trochanter tubercle. 9. Hindleg, anterior view (male from Angelo Coast Range Reserve, California), arrow indicating trochanter tubercle. 10. Macerated abdomen (CNC1155821), ventral view, arrow indicating process of sternite 5. Abbreviation: hypd—hypandrium.

FIGURES 17–24. Habitus, abdomen and hindleg of Microphorella bifida sp. nov., M. convoluta sp. nov., M. paracroptera sp. nov. and M. serpentina sp. nov. 17. Habitus of M. bifida sp. nov. male holotype 18. Male hindleg and abdomen of M. bifida sp. nov. paratype, right lateral view, arrow indicates trochanter tubercle. 19. Process of male abdominal sternite 5 (macerated) of M. bifida sp. nov. (CNC1155824), posterior view. 20. Female abdomen of M. bifida sp. nov. paratype, left lateral view of posterior segments. 21. Male hindleg of M. convoluta sp. nov. holotype, anteroventral view of basal segments, arrow indicates trochanter tubercle. 22. Same except, hind tibia and tarsus, lateral view, arrow indicates spur-like seta on basitarsus. 23. Male hindleg, thorax and abdomen of M. paracroptera sp. nov. holotype, left lateral view, arrow indicates trochanter tubercle. 24. Male hindleg of M. serpentina sp. nov. paratype, posterior view, arrow indicates trochanter tubercle.

FIGURES 47–51. Male habitus, hindleg and abdomen of Microphorella sinuosa sp. nov. 47. Habitus of holotype. 48. Legs of holotype, left lateral view, arrow indicates trochanter tubercle. 49. Abdomen of holotype, dorsal view, arrow indicates process of sternite 5. 50. Process of sternite 5 (CNC1155835), posterior view. 51. Abdomen and right hindleg of paratype (Elk Grove, California), lateral view, arrows indicate trochanter tubercle and process of sternite 5.

FIGURES 64–66. Habitus, thorax, abdomen and hindleg of Microphorella tubifera Melander male from Redwood City, California. 64. Habitus, left lateral view. 65. Habitus, right lateral view. 66. Thorax, abdomen and hindleg, right lateral view, arrows indicate trochanter tubercle and process of sternite 5.

FIGURES 71–77. Male habitus, hindleg and abdomen of M. acuminata sp. nov., M. compacta sp. nov. and M. cornuta sp. nov. 71. Habitus of M. acuminata sp. nov. holotype. 72. Habitus of M. compacta sp. nov. holotype. 73. Mid and hindleg of M. compacta sp. nov. holotype, arrow indicating trochanter tubercle. 74. Abdomen of M. compacta sp. nov. holotype, right lateral view. 75. Same, dorsal view. 76. Abdomen and hindlegs of M. cornuta sp. nov. paratype (Portola Valley, California), right lateral view. 77. Same, left lateral view, arrow indicating trochanter tubercle.

FIGURES 92–96. Male habitus, hindleg, wing and abdomen of Microphorella trochanterata sp. nov. 92. Habitus of holotype, arrow indicates setae of sternite 8. 93. Left hindleg of holotype, posterior view. 94. Same, anterior view. 95. Wing of paratype (Carmel Valley, California). 96. Abdomen of holotype, arrow indicates process of sternite 6. Abbreviations: bm-m—basal medial crossvein; cua—anterior cubital (=anal) cell; CuA—anterior branch of cubital vein; CuA+CuP—anterior branch of cubital vein + posterior branch of cubital vein; dm—discal medial cell; h—humeral crossvein; M1, M2, M4—medial veins; R1, R2+3, R4+5—radial veins; Sc—subcostal vein.

FIGURES 4–5. Male holotype of Microphorella acroptera Melander. 4. Habitus, with wing inset (see Fig. 95 for fully labelled wing). 5. Labels.

FIGURES 86–89. Male habitus, head and wings of Microphorella maculata sp. nov. holotype. 86. Habitus. 87. Head, anterior view. 88. Right wing. 89. Left wing. Abbreviation: CuA+CuP—anterior branch of cubital vein + posterior branch of cubital vein.

FIGURES 41–46. Male terminalia of Microphorella serpentina sp. nov. 41. Hypopygium (CNC1155814), left lateral view. 42. Same, right lateral view. 43. Cerci and hypoproct (CNC1155828), dorsal view. 44. Phallus (CNC1155828), left lateral view. 45. Same, right lateral view. 46. Sternite 5 (CNC1155813), ventral view.Abbreviations: cerc—cercus; epand—epandrium; hypd— hypandrium; hyprct—hypoproct; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 67–70. Male terminalia of Microphorella tubifera Melander (CNC1155805). 67. Hypopygium, left lateral view. 68. Same, right lateral view. 69. Cerci, dorsal view. 70. Sternite 5, posteroventral view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; hypd—hypandrium; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur— ventral lobe of surstylus.

FIGURES 11–16. Hypopygium of Microphorella acroptera Melander and M. subacroptera sp. nov. 11. Hypopygium of M. acroptera (CNC1155812), left lateral. 12. Same, right lateral. 13. Phallus and ejaculatory apodeme of M. acroptera (CNC1155834), left lateral. 14. Same, right lateral. 15. Same except, isolated posterior view of phallus. 16. Right dorsal surstylus of M. subacroptera sp. nov. paratype (CNC1155816), lateral view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; ej apod—ejaculatory apodeme; epand—epandrium; hypd—hypandrium; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 25–28. Hypopygium of Microphorella bifida sp. nov. 25. Hypopygium (CNC1155831), left lateral view. 26. Same (CNC1155824), right lateral view. 27. Phallus (CNC1155824), ventral view. 28. Cerci (CNC1155831), dorsal view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; hypd—hypandrium; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 29–31. Hypopygium of Microphorella convoluta sp. nov. holotype. 29. Hypopygium, right lateral view. 30. Same, left lateral view. 31. Cerci, dorsal view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 36–40. Hypopygium of Microphorella paracroptera sp. nov. 36. Hypopygium (CNC1155811), left lateral view. 37. Same, right lateral view. 38. Same, dorsal view. 39. Phallus (CNC1155809), left lateral view. 40. Same, right lateral view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; hypd—hypandrium; hyprct—hypoproct; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 52–55. Hypopygium of Microphorella sinuosa sp. nov. 52. Hypopygium (CNC1155830), left lateral view. 53. Same, right lateral view. 54. Tip of ventral epandrial process (CNC1155835, CNC1155836), left lateral view. 55. Cerci (CNC1155836), dorsal view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; hypd—hypandrium; pgt lb—postgonite lobe; ph— phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 78–80. Hypopygium of Microphorella acuminata sp. nov. and M. cornuta sp. nov. 78. Hypopygium of M. acuminata sp. nov. (CNC1155844), left lateral view. 79. Hypopygium of M. cornuta sp. nov. (CNC1155802), left lateral view. 80. Same, right lateral view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; epand—epandrium; hypd—hypandrium; hyprct—hypoproct; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 81–85. Hypopygium of Microphorella compacta sp. nov., M. elongata sp. nov. and M. tenuis sp. nov. 81. Hypopygium of M. compacta sp. nov. (CNC1155837), left lateral view. 82. Cerci and hypoproct of same specimen, dorsal view. 83. Hypopygium of M. elongata sp. nov. holotype (CNC1155833), right lateral view. 84. Same, left lateral view.85. Hypopygium of M. tenuis sp. nov. (CNC1155838), left lateral view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; epand— epandrium; hypd—hypandrium; hyprct—hypoproct; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 90–91. Hypopygium of Microphorella maculata sp. nov. holotype. 90. Left lateral view. 91. Right lateral view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; epand—epandrium; hypd—hypandrium; hyprct—hypoproct; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 97–99. Hypopygium of Microphorella trochanterata sp. nov. (CNC1155849). 97. Hypopygium, right lateral view. 98. Same, left lateral view. 99. Cerci, dorsal view. Abbreviations: cerc—cercus; d sur—dorsal lobe of surstylus; epand— epandrium; hypd—hypandrium; pgt lb—postgonite lobe; ph—phallus; v epand proc—ventral epandrial process; v sur—ventral lobe of surstylus.

FIGURES 100–101. Known geographical distribution of the Microphorella acroptera species group. 100. Microphorella acroptera Melander and M. convoluta sp. nov. 101. Microphorella bifida sp. nov., M. triangulata sp. nov. and M. tubifera Melander.

FIGURES 102–103. Known geographical distribution of the Microphorella acroptera species group. 102. Microphorella paracroptera sp. nov., M. sinuosa sp. nov. and M. subacroptera sp. nov. 103. Microphorella acuminata sp. nov., M. compacta sp. nov. and M. cornuta sp. nov.

FIGURES 104–105. Known geographical distribution of the Microphorella acroptera species group. 104. Microphorella serpentina sp. nov., M. elongata sp. nov. and M. tenuis sp. nov. 105. Microphorella maculata sp. nov., M. trochanterata sp. nov. and Microphorella sp. A.

FIGURES 1–3. Collection localities and habitats of the Microphorella acroptera and M. arcana species groups. 1. Santa Ana River, California. 2. Jedediah Smith Redwoods State Park, California. 3. Carson Slough, Ash Meadow National Wildlife Refuge, Nevada (photo by Justin Runyon).