Cirrula gigantea Cresson 1915

Cirrula gigantea Cresson

Cirrula gigantea Cresson, 1917:71.—Sturtevant and Wheeler, 1954: 162 [review].—Wirth, 1965:753 [catalog].

Pogonephydra chalybea Hendel, 1917:42; 1931:10 [synonymy].

DIAGNOSIS.—Specimens of C. gigantea may be distinguished from those of C. austrina by the following combination of character states.

Adults: Lateroclinate fronto-orbital bristles short; cruciate intrafrontal bristles short, less than one-half length of arista, not overlapping apically; parafrons blackish brown, densely pollinose, appearing velvety; aristal rays short, less than aristal width at base; face with dense patch of long bristles subdorsally, just below interfoveal carina; dorsocentral bristles with only posterior pair well developed, anterior 4 pairs barely discernible from surrounding setulae; presutural bristle weakly developed, less than one-half length of anterior notopleural bristle; tarsi of front leg of male broadly explanate; hypandrium weakly sclerotized; setae of epandrium around cercal cavity conspicuously more dense and longer than other setae.

Third-Instar Larva: Transverse sclerotized strap of third segment approximately 6 times as wide as long and with posterior projection, somewhat lighter colored; overall length of larva up to 17.5 mm; cephalopharyngeal skeleton 0.9–1.0 mm in length.

DESCRIPTION OF ADULT.—Large shore flies, length 5.81 to 8.52 mm; mostly dull, olivaceous brown to grayish green, with subshiny to shiny areas on dorsum.

Head (Figures 37, 38): Head width-to-height ratio averaging 1: 0.65; frons width to length ratio averaging 1: 0.74; mesofrons with median shallow depression between median ocellus and ptilinal suture, shiny, with deep metallic greenish blue luster, median depression appearing more pollinose because of depression angle; intrafrontal bristles convergent but not cruciate, short, at most equal to combined length of first 2 antennal segments; remainder of mesofrons with small setulae; ocellar triangle and parafrons pollinose, ocellar triangle blackish brown; parafrons blackish, appearing velvety; ocelli arranged in equilateral triangle; lateroclinate fronto-orbitals small, less than combined length of antenna; postocellar setae mostly small, length no longer than distance between ocelli; postocular setae uniform in size, generally small. Antenna mostly unicolorous, brown to blackish brown; arista about as long as combined length of first 3 antennal segments, basal third to half more or less uniformly thickened, ending abruptly, apical one-half to two-thirds, slender, stylelike, longest aristal rays not greater than aristal width at base. Face width-to-height ratio averaging 1: 0.79; interfoveal carina prominent, dorsolateral margins angled sharply, dorsum shiny, mostly concolorous with mesofrons, with dense patch or patches (somewhat divided medially) of well-developed bristles just below dorsum of interfoveal carina, other facial setae weak except along oral margin; antennal fovea deeply depressed, coloration similar to remainder of face, grayish brown to brown, slightly darker dorsally, with some olivaceous color laterally; oral margin shallowly emarginate toward middle. Eye width-to-height ratio averaging 1: 1.24; eye-to-cheek ratio averaging 1: 0.44; gena moderately high, mostly bare directly below eye but with a row of setae along anterior margin of parafacies and several setae posteriorly, the latter becoming more well developed posteroventrally; gena more or less concolorous with face, more olivaceous.

Thorax (Figure 39): Mesonotum dull to subshiny, becoming darker and shinier posteriorly; with longitudinal pollinose vittae between subshiny ones, these more evident anteriorly, color olivaceous to brown, subshiny areas with metallic greenish blue luster; acrostichal setae unseriated; dorsocentral bristles 5 pairs, anterior 4 pairs much reduced, only slightly larger than surrounding setulae, posterior pair well developed; presutural bristle reduced, generally inconspicuous. Pleural areas lighter and more densely pollinose than dorsum; mesopleuron and pteropleuron more or less concolorous, olivaceous brown, sternopleuron mostly grayish, especially anteriorly, becoming lightly olivaceous brown posteriorly. Legs generally dark colored, dull densely pollinose, sexually dimorphic; dorsum of femora grayish green, becoming more brownish laterally and ventrally; tibiae nearly concolorous with femora, except becoming conspicuously darker apically, blackish; tarsi black; hind femora of male turgid (Figure 41); hind tibiae of male with apicoventral patch of long setae; hind tarsi moderately explanate, bearing a row of long setae along anterior margin, especially evident on basitarsus; front tarsi of male (Figure 40) conspicuously explanate posteriorly. Wing (Figure 112) length averaging 5.7 mm; generally subhyaline to lightly infuscated, light brown; costal vein index averaging 1: 0.18; vein M index averaging 1: 0.95; wing length-to-width ratio averaging 1: 0.44.

Abdomen: Subshiny to shiny, sparsely pollinose; olivaceous to distinctly bronzish. Fifth tergum of male longer than basal width, triangular, apical setae larger especially along margin.

Male Terminalia (Figures 42–44): Epandrium more or less parallel sided in caudal view, slightly broader medially, comparatively flattened in profile, with anteroventral angulation; surstylus digitiform, 4 to 5 times longer than wide, recurved apically to corniform apex; gonite complicate basally (Figure 42), apically forming lunate process; aedeagus bifurcate, posterior lobe with apical two-thirds more or less rectangular, posteroventral corner forming acuminate narrow tip, anterior lobe as long as posterior lobe, basal two-thirds parallel sided, apical one-third abruptly narrowing to tapering narrow process, rounded apically; hypandrium with poorly sclerotized anterior ribbon; aedeagal apodeme more or less triangular in profile, basally bifurcating at juncture with each lateral gonite.

Female Terminalia: Female ventral receptacle (Figure 45) with operculum as high as wide, broadly rounded, slightly flattened dorsally; extending process short, distinctly narrowed apically, shallowly curved. Segments 6 and 7 complete; sixth spiracle situated near anteroventral corner of sixth tergum; sixth sternum narrowly rectangular, about 3 times longer than wide, more setose posteriorly; seventh sternum narrowly rectangular, about two and one-half times longer than wide, more setose posteriorly. Eighth segment as follows: tergum divided into 2 lateral tergites, each gradually becoming wider ventrally; sternum divided longitudinally, each sternite about 3 times longer than wide, narrowed and more setose posteriorly, bearing 3–4 large apical setae. Ninth sternum sclerotized basally, divided, with poorly sclerotized area posteriorly and lacking dividing sulcus, setose more toward base, each sternite with 1 large bristle, well developed; ninth tergites fused with cerci and each bearing 1 large bristle posteroventrally.

DESCRIPTION OF IMMATURE STAGES.—Egg (Figure 46): Length 0.75–0.90 mm (x = 0.82); maximum width in dorsal view 0.25–0.36 mm (x = 0.31). Ovoid; egg membranes transparent. Similar to C. austrina except in the following characters. Yellowish orange just after oviposition, becoming lighter yellow to dull white during development. Surface of chorion nodulose, without reticulate pattern. Micropyle in less distinct circular depression and surrounded by pale, flat, spinelike processes. Opposite end somewhat tapered posteroventrally. (Based on 27 specimens from rearings.)

First-Instar Larva: Main body length is 1.64–2.41 mm, respiratory tube length 0.31–0.47 mm; maximum width in dorsal view 0.31–0.33 mm. Similar to C. austrina except in the following characters. Posterior spiracular caps as in Figure 50 very similar. Cephalopharyngeal skeleton length 0.29–0.31 mm. (Based on 17 reared specimens.)

Second-Instar Larva: Main body length 3.50–5.53 mm, respiratory tube length 0.75–1.34 mm; maximum width in dorsal view 0.59–0.78 mm. Similar to C. austrina except in following characters. Anterior spiracles (Figure 47) very similar, with 5–6 marginal papillae. Prolegs lacking distinct glabrous borders anteriorly and posteriorly. Posterior spiracular caps (Figure 51) very similar. Cephalopharyngeal skeleton (Figure 54) length 0.51–0.54 mm; posterior arms of epistomal sclerite more slender and less diverging; lateral pharyngeal processes fused to pharyngeal sclerite. (Based on 26 specimens, 20 reared and 6 field collected.)

Third-Instar Larva (Figures 57, 58): Main body length 9.08–12.83 mm, respiratory tube length 2.89–4.83 mm; maximum width in dorsal view 1.66–2.83 mm. Similar to C. austrina except in following characters. Integument covering somewhat less dense, arcs of glabrous patches less evident. Antennae smaller. Anterior spiracles (Figure 48) very similar, usually with 6 marginal papillae. Transverse strap on segment 3 thicker and with a somewhat lighter perpendicular projection extending posteriorly (Figure 49). Venter of segments 3 and 4 more evenly spinose; distinct light areas absent. Posterior spiracular caps (Figures 52, 53) very similar; slightly larger. Cephalopharyngeal skeleton (Figure 56) length 0.92–0.98 mm. Mouthhook length 0.17–0.19 mm. Hypostomal sclerite length 0.28–0.32 mm. Posterior arms of epistomal sclerite more slender and less diverging (Figure 55). Pharyngeal sclerite length 0.42–0.50 mm, indentation index 67–75; lateral pharyngeal processes attached; dorsal cornua with more abundant dark rays. (Based on 19 specimens, 6 reared and 13 field collected.)

Puparium (Figures 59, 60): Main body length 7.07–9.33 mm (x = 8.56), respiratory tube length 4.40–6.09 mm (x = 5.27); maximum width in dorsal view 2.07–2.83 mm (x = 2.53). Similar to Cirrula austrina except in the following characters. Transverse sclerotized strap on segment 3 with lighter posterior projection. Prolegs 6 and 7 moderately swollen and protruding; terminal proleg (P8) swollen and protruding, usually opposed to P7. (Based on 33 specimens, 3 reared and 30 field collected.)

TYPE MATERIAL.—Holotype male of the senior synonym is labeled: “/Cohasset IX [Sep] 8 [19] 04 Mass[achusetts][date handwritten]/HoloTYPE 6072 [number handwritten, red]/HoloTYPE Cirrula gigantea E. T. Cresson Jr [name and sex symbol handwritten, red].” Three female paratypes have the same locality data as the holotype. The holotype is pinned directly, is in poor condition (the head is missing, both wings slightly torn), and is deposited in the Academy of Natural Sciences of Philadelphia, type number 6072. One of the female paratypes is labeled as an allotype, although none was designated in the original description. The holotype female of the junior synonym is labeled: “White Mount[ain] [New Hampshire] 879-I/Pogonephydra chalybea H. det. Hendel [name and initial handwritten]; Coll. Hendel.” The holotype is pinned directly, is in fair condition [the right wing is tattered, the left wing was removed and slide mounted], and is deposited in the Naturhistorisches Museum, Wien, Austria.

OTHER SPECIMENS EXAMINED.—CANADA. NEW BRUNSWICK: Kouchibouguac National Park, 8 May 1977, J. E. H. Martin, J. F. McAlpine (1, 1; CNC); Shippigan, 14 Jul 1931, J. M. Aldrich (16, 49; USNM). NOVA SCOTIA: Baddeck, 16 Jul 1936, T. N. Freeman (8, 10; CNC); Lockeport, 29 Jul–9 Aug 1958, J. R. Vockeroth (4, 4; CNC); Petite Riviera, 12–18 Jul 1935, J. McDunnough (2; CNC); Sable Island, 11–15 Sep 1967, W. R. M. Mason (1; CNC). PRINCE EDWARD ISLAND: Brackley Beach, Canadian National Park, 25–28 Jul 1940, J. McDunnough (1, 7; CNC); Green Gables, Cavendish Beach, 22 Jul 1967, D. M. Wood (1; CNC). QUEBEC: Alright Island, 17 Aug 1917, F. Johansen (3, 5; CNC); New Richmond, 6 Aug 1954, J. E. H. Martin (31, 39; CNC); Notre Dame du Portage, 17 Aug 1957, W. J. Brown, W. R. M. Mason (3, 1; CNC). UNITED STATES. CONNECTICUT: Fairfield Co., Stratford (1; USNM). New Haven Co., New Haven, W shore of harbor, 29 Jul 1961, D. L. Deonier (58, 52; DLD). MAINE: Hancock Co., Narrows, Mt. Desert, 13 Aug 1900, C. W. Johnson (1, 1; USNM). Sagahadoc Co., Popham Beach, 14 Jul 1971, P. Ward (1; CNC). Washington Co., Machias, 17 Aug 1909, C. W. Johnson (1, 1; USNM). MASSACHUSETTS: Barnstable Co., Cape Cod, 10 Sep, Scudder (1; USNM); Chatham, 30 Jun 1904, C. W. Johnson (1; USNM); Eastham, 27 Jun 1904, C. W. Johnson (1; USNM); Falmouth Heights, 6 Aug 1918 (2; USNM); Provincetown, 18 Aug 1926, A. L. Melander (1; USNM); Woods Hole, 22 Jul-2 Aug 1899–1900 (3; AMNH, USNM). Dukes Co., Naushon Island (1; USNM). Essex Co., Gloucester, 24 Jun 1924, C. W. Johnson (2; CNC); Ipswich, 22 Jul 1961, W. W. Wirth (1; USNM); Nahant, 6 Jul 1919, C. C. Sperry (1, 3; USNM). Norfolk Co., Brookline, F. C. Bowditch (1; USNM); Cohasset, 8 Nov 1904, C. W. Johnson (2; USNM). Suffolk Co., Boston, vicinity of, 29 Jun 1908, W. E. Britton (1; USNM). NEW HAMPSHIRE: White Mountains (1, 1; AMNH, USNM; questionable, see “Remarks” section).

GEOGRAPHIC DISTRIBUTION (Figure 61).—Cirrula gigantea occurs along the coast of eastern North America from between 41° and 49° north latitude.

NATURAL HISTORY.—Field notes were recorded and laboratory rearing initiated with material from the following localities and dates. Connecticut: New Haven Co., Plum Bank Beach, 1 Jun 1971, 6 Aug 1971. Massachusetts: Barnstable Co., Eastham, 25 May 1969, 4 Aug 1971. The earliest seasonal record for adults is 27 Mar (Massachusetts); the latest, 24 Sep (Massachusetts).

Adults were observed walking on salt marshalgae and mud, and were also taken by sweeping the marsh habitat. They were much less abundant than Ephydra subopaca Loew and Dimecoenia spinosa, two other species of Ephydrini occurring in the same marshes. Adults are strong fliers, commonly flying out of sight after being disturbed. No courtship or mating behavior were observed, although a male of an Ephydra species once mounted a female of Cirrula gigantea but was quickly dislodged.

Larvae and puparia were found infrequently during the months of July, August, and September. An algal mat approximately two feet in diameter at Plum Bank Beach yielded 38 puparia on 1 Jun 1971 (Figure 117). These puparia produced 29 adults of C. gigantea and one parasitoid wasp (Pteromalidae, Belonura singularis Ashm.); eight were inviable.

When confined in laboratory breeding containers, adults were comparatively awkward and clumsy. They often attempted to climb up the sides of the container, only to fall into the bottom. They also attempted to fly out, making a distinctly audible sound as they hit the sides and lid of the containers. Larger rearing chambers were constructed from 18 × 13 × 36 cm plastic boxes in an attempt to increase the flies' longevity. Each container was supplied with moist peat moss, three to five small petri dishes filled with salt marsh algae, and small clumps of grass. The flies, however, lived no longer than those confined in the smaller containers.

No eggs were found in nature, but females readily oviposited in the rearing containers, usually on or within the salt marsh algae, but also occasionally in the peat moss. Maximum recorded egg production was 252 eggs during a 14-day period; the maximum daily output was 47 eggs.

The incubation period was two days (66 observations). Newly hatched larvae usually fed readily on field-collected salt marsh algae. A few larvae initially crawled away from the algae, but later returned and commenced feeding. The feeding mechanism, as well as the overall appearance and behavior, is very similar to that of C. austrina.

The first stadium lasted two to three days (25 observations); the second, three to five days (21 observations); the third, five to eight days (18 observations). Larvae of all three instars were usually feeding when observed, at times being completely covered by the algae with the exception of the posterior spiracles. Puparia were formed just beneath the surface of the substrate, with the respiratory tube projecting slightly above. The pupal stage lasted eight to twelve days (17 observations).

Cirrula gigantea is a species of shore flies in the family Ephydridae.

On saltmarshes.