Dineutus ciliatus (Forsberg, 1821)

Gustafson, Grey T. & Miller, Kelly B., 2015, The New World whirligig beetles of the genus Dineutus Macleay, 1825 (Coleoptera, Gyrinidae, Gyrininae, Dineutini), ZooKeys 476, pp. 1-135 : 36

Dineutus ciliatus (Forsberg, 1821) Figures 12, 13, 53

Gyrinus ciliatus Forsberg 1821: 312, Gyrinus vittatus Germar 1824: 32 [synonymy by Ochs 1925b], Cyclous vittatus : Dejean 1833: 58, Dineutes vittatus : Brullé 1835: 240, Cyclous opacus Melsheimer, 1846: 29 [synonymy by LeConte 1868], Dineutus vittatus : LeConte 1868: 366, Dineutes vittatus : Régimbart 1882: 411, [ Dineutes hastatus : Régimbart 1882: 426 misidentified], Dineutes ciliatus : Severin 1889: 152, Dineutes vittatus : Severin 1889: 155, Dineutes opacus : Severin 1889: 154, Dineutes vittatus : Régimbart 1892: 739, [ Dineutes hastatus : Régimbart 1892: 740 misidentified], Dineutes inflatus Blackburn 1895: 28 [synonymy by Ochs 1926a], Dineutus ciliatus : Ochs 1925b: 174, Dineutus (Dineutus) vittatus : Hatch 1926: 311, Dineutus (Dineutus) ciliatus : Ochs 1926a: 138, Dineutus vittatus : Leonard 1928: 262, Dineutus ciliatus : Ochs 1930: 135, Dineutus (Dineutus) ciliatus : Hatch 1930: 19, Dineutus vittatus : Blackwelder 1944: 81. Dineutus (Dineutus) ciliatus : Ochs 1949: 286, Dineutus (Protodineutus) ciliatus : Guignot 1950: 126, Dineutus (Cyclinus) ciliatus : Brinck 1955: 106, Dineutus ciliatus : Ciegler et al. 2003: 15.

Type locality.

East Indies, likely in error. The type is labeled, “Ind.” according to Ochs (1949), which Young (1954) suggested could refer to Indiana, though Forsberg’s (1821) indicated "Indies oriental."

Specimens examined.

73

Type material.

Not examined. Ochs (1925b) examined Forsberg’s types when establishing his synonymies, therefore the identity of Dineutus ciliatus is well established in relation to its most common synonym Dineutes vittatus .

Material examined.

U.S.A.: Alabama: U.S.A.: Alabama: Conecuh Co., 13 km E Evergreen on Hwy 31, Old Town Creek, 31°27.037'N, 86°49.81'W, 53 m, 11.v.2006, leg. K.B. Miller, KBM1105061 (6 ex. MSBA); Marion Co., Barnsville, 23.viii.1931, leg. R.H. Beamer (1 ex. KSEM); Connecticut: New London Co., New London, 16.v.1931, leg. M. Sanderson (1 ex. KSEM); Delaware: New Castle Co., Glasgow, 4.v.1957, leg. L.R. Krusberg (1 ex. FSCA); Louisiana: Beaugarl Co., 13.viii.1928, leg. R.H. Beamer Jr. (4 ex. KSEM); Maryland: Prince George’s Co., College Park, 4.x.1947, leg. B.K. Dozier (6 ex. FSCA); Massachusetts: Hampshire Co., Amherst, 16.vi.1904 (1 ex. MTEC); Norfolk Co., Blue Hills Reservation, v.1929, leg. G.C. Wheeler (1 ex. FSCA); New Jersey: Bergen Co., Dumont Woods, 9.iv.1931, leg. C.L. Ragot (1 ex. FSCA); Bergen Co., Woodcliff Lake, 20.v.1934 (3 ex. FSCA); Gloucester Co., 1 mi S Paulsboro, 3.vii.1959, leg. H.L. Dozier (4 ex. FSCA); Ocean Co., Cassville, branch of Tom’s River, vi.1931, leg. Siepmann (4 ex. FSCA); Lakehurst, 6.v.1934, leg. C.L. Ragot (1 ex. FSCA); New York: Westchester Co., White Plains, 2.x.1921, leg. E.H.P. Squire (1 ex. FSCA); same as previous except: 23.viii.1922 (2 ex. FSCA); same as previous except: 5.ix.1922 (2 ex. FSCA); 10.vi.1923 (19 ex. FSCA); North Carolina: Wake Co., Raleigh, leg. S.P. Whitney (1 ex. FSCA); Oklahoma: Larimer Co., 5 mi W Red Oak, 2.vii.1977, leg. K.H. Stephan (7 ex. FSCA); U.S.A.: Oklahoma: Larimer Co., 5 mi W Red Oak, vii.1980, leg. K.H. Stephan (1 ex. FSCA); Murray Co., Arbuckle Mts., nr Davis, 21.vi.1922 (1 ex. FSCA); Rhode Island: Kent Co., “Greenwich”, 15.vii.1934, leg. W. Sanderson (3 ex. KSEM); South Carolina: Sumter Co., 29.iv.1968, leg. L.L. Lampert, on stream (1 ex. FSCA). No locality information: “Station.”, 8.viii.1901, "Hatch Ex." (1 ex. MTEC).

Diagnosis.

Male (Fig. 12C-D): Size: 12.7-14.6 mm. Body form broadly roundly oval; antennal flagellum thick and round, ultimate segment rounded; elytral apices regularly rounded, serration absent, elytra with bronzy lateral stripe disappearing apically, elytral striae weakly developed, 8th elytral stria without punctures present or strongly evident; profemora without sub-apicoventral tooth; protibiae club-shaped; anterior mesotarsal claw (Fig. 13C) with denticle; venter normally dark reddish brown, rarely reddish orange (teneral individuals); Aedeagus (Fig. 13A, B, D) medial lobe in dorsal view with apicomedial papilla, in ventral view sperm-groove parallel sided, in lateral view median lobe curved, apically narrow, parameres weakly rounded laterally in apical 1/3.

Female (Fig. 12A-B): Size: 11.5-14.6 mm. Body form broadly roundly oval; Antennal flagellum thick and round, ultimate segment rounded; elytral apices regularly rounded, serration absent, elytra with bronzy lateral stripe disappearing apically, elytral striae weakly developed, 8th elytral stria without punctures present or strongly evident; profemora without sub-apicoventral tooth; protibiae club-shaped; venter normally dark reddish brown, rarely reddish orange (teneral individuals).

Differential diagnosis.

This species is most easily distinguished from other members of North American Dineutus by the presence of a bronzy lateral stripe on each elytron, a regularly oval body form, large size, absence of a profemoral sub-apicoventral tooth in the male, and the form of the male aedeagus (Fig. 13A). Dineutus ciliatus is most similar to Dineutus robertsi , but there are several characters that readily separate the two species. Both sexes of Dineutus ciliatus have the venter dark reddish brown in color instead of light yellowish orange (most evident on the epipleura), the antennal flagellum thicker and rounder with the ultimate segment rounded instead of thinner and more parallel sided with an angled ultimate segment, and the 8th elytral stria with punctures absent or indistinct. The venter coloration of teneral individuals is lighter, reddish orange, but this does not closely approach that of Dineutus robertsi , which is much more yellow in color. Males of Dineutus ciliatus also have the anterior mesotarsal claws with a more weakly developed denticle on their ventral surface, and a smaller general body size than Dineutus robertsi . The aedeagus (Fig. 13) of Dineutus ciliatus has the median lobe narrow and dorsally curved in lateral view with an apicomedial papilla visible in both dorsal and ventral views. The sperm-groove is much more parallel-sided in Dineutus ciliatus than Dineutus robertsi . Finally, the parameres of Dineutus ciliatus are weakly lateral curved in the apical 1/3 instead of strongly curved as in Dineutus robertsi .

Distribution

(Fig. 53B). Most of the eastern half of the United Sates ( Folkerts 1978; Malcolm 1971; Sanderson 1982; Wood 1962; Young 1954).

Habitat.

This is a lotic species ( Young 1954; Hatch 1927). In Florida Dineutus ciliatus is commonly found in small, shaded streams, and when found in larger streams prefers to stay near the stream bank ( Young 1954). Hatch (1927) describes one habitat of Dineutus ciliatus in Massachusetts as a small sandy bottomed stream, approximately five feet wide and with a depth from six to ten inches, with a flow rate of one foot per second or less. Hatch (1927) also noted that Dineutus ciliatus prefers to reside near the bank of the stream. In east Texas this species was only collected in lotic situations at East Texas Primitive Big Thicket ( Realzola et al. 2007). The first author has collected Dineutus ciliatus from both small pebble bottomed forested streams, to larger mud-bottomed rivers, throughout the southeastern United States, where it is quite commonly encountered.

Discussion.

Dineutus ciliatus is a common species with a wide range (Fig. 53B) and is frequently collected and represented in collections in large numbers.