Penola eudyptidis Richards

Kits, Joel H. & Marshall, Stephen A., 2011, A revision of Frutillaria Richards and Penola Richards (Diptera: Sphaeroceridae: Archiborborinae), Zootaxa 2863, pp. 1-34 : 30-33

Penola eudyptidis Richards

( Figs. 56–58 , 104–106 , 109 )

Penola eudyptidis Richards, 1941: 324 –326

Small flies, 2.4–3.2 mm long.

Head, clypeus, and prementum yellow, a medial brown patch on upper occiput extending anteriorly onto frons. Head mostly covered with very fine microtomentum, but frons with a medial shiny patch behind ocellar triangle, surrounding postocellar bristles, and a lateral patch along eye anterior to vertical bristles. Face evenly sclerotized, lunule small. Gena about ¼ maximum height of eye. Occiput narrow below occipital foramen. Clypeus narrow, slightly produced. Palpus broadest distally, with tiny setae throughout and larger setae along lateral margin. Prementum well-developed, circular, about ¾ height of eye. Labellum with 12 pseudotracheae. Scape very short, with 2 dorsal setulae; pedicel subtriangular, with a single row of apical bristles, medial bristles about 3 times the length of outer bristles, uppermost apical upcurved, with a downcurved bristle posterior to it; first flagellomere round, slightly pointed dorsoapically; arista dorsolateral, preapical, 2-segmented, about as long as head length, finely plumose. Chaetotaxy: orbital bristles in two lateroclinate pairs; orbital setulae situated irregularly along orbital plate; interfrontals in 4–5 medioclinate pairs; preocellars about 1 ocellus width anterior of central ocellus, lateroproclinate; ocellar setulae irregular; inner vertical bristles inclinate; outer vertical bristles lateroreclinate; postocellar bristles slightly proclinate; postvertical bristles small, cruciate; inner occipital setae small, medioclinate; outer occipital setae two rows, inner row incomplete; vibrissa strong, as long as head; no distinct subvibrissal bristle; upturned genal bristle about ¼ length of vibrissa; genal setae in 2 rows.

Thorax appearing somewhat dorsoventrally compressed, scutum quite flat, scutellum very short (width about 4x length); wing rudiment less than ½ length of thorax. Yellow with a brown stripe in middle of mesoscutum between dorsocentral rows, metapleuron brown, wing rudiment yellow. Mesoscutum without microtomentum but medially microsculptured with fine irregular ridges, so not appearing shiny. Scutellum covered with microtomentum. Anepisternum mostly shiny, with a patch of microtomentum along anterior margin. Proepisternum with 1–2 setulae. Katepisternum mostly covered with microtomentum, with a shiny patch posteriorly extending onto meron; metapleuron entirely covered with microtomentum. Halter absent. Chaetotaxy: postpronotum with a single enlarged bristle; notopleuron with two bristles, anterior very long, about 2x length of posterior; one postsutural intra-alar bristles; one large postalar bristle behind wing rudiment and a smaller postalar between this and scutellum; one pair of prescutellar dorsocentral bristles; scutellum with 2 pairs of bristles, basal bristles about as long as scutellum, apical bristles variable, from similar length to basal bristles to as long as width of scutellum; acrostichal setae in 2 rows; katepisternum with a single large dorsal bristle and long, thin setae ventrally.

Legs yellow. Fore tibia with a preapical dorsal bristle. Fore basotarsomere with a ventral projection apically in males, unmodified in female. Mid femur with 2 anterior bristles, 1 dorsal bristle. Mid tibia with preapical anterodorsal, anteroventral, and posteroventral bristles and a ring of 4–5 apical bristles; posteroventral bristle apparently absent in some individuals. Hind femur with a long curved dorsal bristle. Hind tibia with a long preapical dorsal bristle and 2 apicoventral bristles.

Male abdomen ( Figs. 56–58 ): Black, flattened. Syntergite 1+2 with a patch of microtomentum at base, otherwise shiny, tergites 3–5 entirely shiny. Sternites wide, strongly sclerotized, shiny. Sternite 5 with a posteromedial indentation surrounded by setae. Synsternite 6+7 asymmetrical, dorsal corner fused to sternite 8. No ring-shaped sclerite between segment 5 and epandrium. Sternite 8 broadly fused to epandrium along right side. Epandrium symmetrical, with a cleft above anterior edge of surstylus. Cerci small and medially fused. Surstylus broad and scoop-like, articulated with epandrium posterior to epandrial cleft and with subepandrial sclerite. Subepandrial sclerite Y-shaped, articulated with cerci and surstyli. Hypandrial arms weakly fused with ventral edge of epandrium; hypandrial apodeme well-developed, rodlike, weakly fused with arms. Postgonite thin, parallel-sided, without lobes; articulated with phallapodeme, hypandrium, and basiphallus. Phallapodeme well-developed, curved and broader distally. Ejaculatory apodeme very small, narrow and sinuous. Basiphallus long, epiphallus and preepiphallus distinct but fairly short. Distiphallus without developed lateral arms, but with a possibly homologous ventral sclerite not reaching level of central projecting sclerite. Tip of ventral sclerite with a round, spinose, translucent area on each side. Central projecting sclerite very thin, rod-like at tip, a spinose area just basal to tip.

Female abdomen ( Figs. 104–106 ): Black, flattened. Sclerites of segments 6 and 7 unusually broad and strongly sclerotized for Archiborborinae , abdomen telescoping. Syntergite 1+2 with a patch of microtomentum at base, otherwise shiny. Tergites 3–5 and possibly 6 entirely shiny, tergite 7 with some microtomentum in lateral patches, shiny medially. Tergite 8 shiny, weakened medially, epiproct triangular, without anterior arms. Sternites 2–7 apparently entirely shiny. Sclerites of sternite 8 comma-shaped, hypoproct partly sclerotized, round posteriorly. Cerci yellow, simple, not fused with epiproct or each other. Spermathecae 3; one pair sharing a duct and a single on a separate duct; slightly oblong, without invaginations, extended at base, with distinct but irregular transverse ribbing.

Immature stages: Unknown.

Type material. Holotype Ƥ: FALKLAND IS: Kidney Island, from neck of the penguin Eudyptes chrysocome nigrivestis Gould (Rock-hopper Penguin), 10 Apr 1936, British Graham Land Expedition ( BMNH, not examined).

Material examined. FALKLAND IS: Kidney Is., in tussock/tussock grass n. coast/under floor old hut, 29–30 Nov 1961, M. Holdgate (3 3, 7 Ƥ, BMNH); Port William, among and under decayed Poa flabellata , 9 Oct 1934, A. G. Bennett (2 Ƥ, BMNH).

Comments. This species is only known from the Falkland Islands, where it appears to be associated primarily with Tussac grass ( Poa flabellata ). In addition to the specimens from Kidney Island and Port William, this species has also been recorded from Beauchêne Island ( Lewis Smith and Prince 1985).

The presence of a member of this flightless clade on the Falkland Islands is intriguing, as there is no evidence that the islands have ever shared a land connection with mainland South America ( McDowall 2005). The species may have travelled to the islands by rafting on flotsam ( Heatwole and Levins 1972) or perhaps by passive sea surface drift ( Peck 1994); these dispersal methods have been invoked to explain the distribution of other flightless arthropods across oceanic barriers (eg. Peck 1990, Howden 1992, Trewick 2000). Intriguingly, another flightless archiborborine, Antrops truncipennis Enderlein , also shows evidence of such dispersal, occurring on several widely separated islands in the area, including the Cape Horn archipelago, Isla de los Estados, the Falkland Islands, and South Georgia Island.

Figures

FIGURES 53 – 58. Frutillaria and Penola male genitalia. F. triangularis: (53) cerci and surstyli, posterior view, (54) surstylus, anterior view, (55) phallus and postgonite, lateral view; P. eudyptidis: (56) postgonite (phallapodeme omitted), (57) surstylus, anterior view, (58) hypopygium, posterior view.

FIGURES 104 – 107. Penola eudyptidis female terminalia: (104) tergite 8, epiproct, circus, (105) sternite 8, hypoproct, (106) spermathecae. (107) Frutillaria transversa male sternite 2 – 5.

FIGURES 108 – 115. Frutillaria and Penola distribution maps. (108) F. abdita, F. f u rc a t a, F. tenuiforceps, F. triangularis; (109) F. anticura, F. chepuensis, F. glabra, P. eudyptidis; (110) F. c o n t u l m o, F. calceata, F. chiloensis, F. propinqua; (111) F. calida; (112) F. edenensis; (113) F. k u s c h e l i, F. r i c ha rds i; (114) F. stenoptera; (115) F. transversa.