Helochares (Hydrobaticus) maculicollis Mulsant, 1844

Short, Andrew Edward Z. & Girón, Jennifer C., 2018, Review of the Helochares (Hydrobaticus) MacLeay of the New World (Coleoptera: Hydrophilidae: Acidocerinae), Zootaxa 4407 (1), pp. 29-50 : 36-38

Helochares (Hydrobaticus) maculicollis Mulsant, 1844

Figs. 3A , 5A , 6B , 7 C–E, 9D, 10A.

Helochares maculicollis Mulsant, 1844: 379 .

Philhydrus (Helochares) maculicollis ( Mulsant, 1844) . LeConte 1855: 370.

Helochares (Grapidelochares) maculicollis Mulsant, 1844 . Zaitzev 1908: 381.

? Helochares bipunctatus Sharp, 1882: 76 . Originally synonymized by: d’Orchymont 1943: 3.

Material examined (221). UNITED STATES: Alabama: Hale Co., Payne Lake, near Brent , 2.vii.1963, leg. P.J. Spangler (3, USNM) . Arkansas: Johnson Co., Clarksville, Horsehead Lake , 20.v.1976, leg. W.E. Steiner (2, USNM) ; Hot Springs Co., 17.x.1956, leg. J. R. Zimmerman (2, USNM) . District of Columbia: “7.6” (1, USNM) . Florida: Alachua Co., 6.ix.1972, leg. Matta (3, USNM) ; Okeechobee Co., iii.1932, leg. Uhler & Nelson (5, USNM) ; Palm Beach Co., 17.viii.1973, leg. Matta (2, USNM) ; Dixie Co., Old Town , v.1967 (1, USNM) ; Econlockhatchee River [no other data] (1, CAS) . Georgia: Terrell Co., Chickasawatchie Creek , SW Bronwood, 29.vi.1962, leg. F.N. Young, #2001 (3, FMNH) . Hart Co., nr. Nuberg , 2.vii.1981 (1, CAS) ; Okefenokee ,

10.vii.1051 (4, CAS). Illinois: Pope Co., 1.2 mi S. Glendale, 20.v.2006, farm pond, leg. W.D. Shepard (2, SEMC) . Indiana: Monroe Co., Morgan Monroe Forest, Lake Bryant , leg. F.N. Young (1, CAS) ; Monroe Co., Pond at Beech Flats , 19.iv.1986, leg. F.N. Young (2, CAS) ; Jackson Co., 2 mi W. Brownstown, pool, 15.x.1983, leg. F.N. Young, #3002 (1, FMNH) , Jackson Co., near Brownstown , 16.ix.1984, leg. F.N. Young, #3044 (5, FMNH) , Jackson Co., W. of Brownstown , pools at bridge on US Hwy 50, 12.ix.1987, leg. F.N. Young, #3256 (3, FMNH, USNM) ; Monroe Co., Bloomington , various dates in 1956, leg. J.R. Zimmerman (7, USNM) . Iowa: Henry Co., Mt. Pleasant , 27.iv.1934, leg. Knutson (1, USNM) . Kansas: Atchison Co., Atchison , 22.ix.1957 leg. J.W. McReynolds (2, CAS) ; same data but 9.ix.1956 (2, CAS) ; Douglas Co., Lone Star Lake , 30.ix.1951, leg. P.J. Spangler (3, USNM) ; Douglas Co., Riverfront Park nr. Lawrence, leg. A.E.Z. Short (3, SEMC) ; Chase Co., State Fishing Lake , under rocks, muddy lake shore, 8.x.2011, leg. Z.H. Falin, KAN1F11 146 (6, SEMC) ; Ellsworth Co., Lake Kanopolis outflow, 16.iii.1976, leg. D. Roubik (3, SEMC) ; Cherokee Co., Shoal Creek at K-26, 13.vi.1979, leg. Gilbert et al. (1, SEMC) ; Nemaha Co., Sabetha City Lake , 25.vi.1974, leg. T. Edmonds (1, SEMC) ; Anderson Co., Pond , 9.4 mi. N. Colony on US 169, 2.vi.1975, leg. T. Edmonds (1, SEMC) ; Leavenworth Co, Tonganoxie Lake, Leavenworth State Park , 1.vi.1952, leg. P.J. Spangler (3, USNM) ; Wyandotte Co., State Lake , 14.viii.1974, leg. T. Edmonds (1, SEMC) . Sedgwick Co., Wichita , 14.vi.1958, leg. Zimmerman (1, UNSM) ; Sedgwick Co., near Derby, 10.vi.1958, leg. Zimmerman (1, USNM) . Kentucky: “near Cin. O.” [ Cincinnati , Ohio], 27.vii.1900 (1, CAS) . Louisiana: Natchitoches Co., Vowell’s Mill (1, CAS) ; “New Orleans”. Maryland: Montgomery Co., Cabin John, Potomac River , 3.vii.1952, leg. G.H. Nelson (2, USNM) ; Talbot Co., 3 k SE Easton, Seth State Forest , 3.viii.1986, leg. Steiner, Hill, & Swearington (1, UNSM) ; Anne Arundel Co., Friendship , various dates, leg. R. Gordon (5, UNSM) ; Montgomery Co., 2 mi. SE of Colesville , 16.viii.1967, leg. Spangler (1, USNM) . Mississippi: [no other data], leg. H.E. Weed (2, USNM) . Missouri: “ St. Louis ” (1, CAS) ; Butler Co., Poplar Bluff, Palmers Slough, leg. 22.iv.1956, leg. P.J. Spangler (1, USNM) ; Boone Co., Columbia, Airport pond, 6.vii.1953, leg. P.J. Spangler (14, USNM) ; Boone Co., Ashland , 17.vii.1953, farm pond, leg. P.J. Spangler (2, USNM) ; Shannon Co., Eminence, Shawnee Creek , 8.iv.1955, leg. P.J. Spangler (2, UNSM) ; Mississippi Co., 1 mi. E. of Charleston , 9.vii.1956, leg. P.J. Spangler (3, USNM) ; Osage Co., Westphilia , 3.v.1955, leg. P.J. Spangler (1, USNM) ; Barry Co., Roaring River State Park, Cassville , 22.iv.1955, leg. P.J. Spangler (7, USNM) ; Shannon Co., Lewis Lake, 2 mi. N. of Winona , 9.iv.1955, leg. P.J. Spangler (9, USNM) ; Maries Co., Vichy , 13.iv.1954, leg. M.C. Grabau (33, USNM) . Ohio: Warren Co., 2 mi S. of Mason , 24.vi.1957, leg. J.R. Zimmerman (1, USNM) . Oklahoma: Harper Co., Hwy 270, 6 mi. W. of May , Clear Creek , 13.viii.1967, leg. H.B. Leech (1, CAS) ; Payne Co., Stillwater , 4.iv.1951 (1, CAS) . Pennsylvania: Chester Co., Nottingham, pond, 20.iii.2002, leg. A.E.Z. Short (8, SEMC) ; same data but 23.vi.2002 (1, SEMC) , same data but 17.v.2002 (1, SEMC) . South Carolina: Aiken Co., Aiken State Park , 31.v.1969, leg. R. Gordon (1, USNM) . Tennessee: Knox Co., Knoxville , 12.v.1940, leg. A.C. Cole (2, CAS) , same data but 17.iv.1940 (3, CAS) . Texas: Bexar Co., San Antonio , 25.vi.1942, leg. E.S. Ross (1, CAS) ; Brazos Co., Fish Lake , 22.iii.1965, leg. Conte (2, CAS) ; same data but 14.ii.1965 (2, CAS) ; “ Dallas ”, leg. Wickham (1, CAS) ; Fayette Co., Engle (1, CAS) ; Nueces Co, Corpus Christi , “11-3-69” (2, USNM) ; Falls Co., “ L. Brazos R. by St. Rd. 6”, 18.x.1956, leg. J. R. Zimmerman (1, USNM) ; La Salle Co., Cotulla , 11.v.1906, leg. F.C. Pratt (1, USNM) ; Fayette Co., 1 mi S. Warda on Rt. 77, large creek, 30.vii.2003, leg. A.E.Z Short, AS-03-004, (12, SEMC) ; Lee Co., Rt. 77 at Elm Creek , 6.5 km N. of Giddings , 30.vii.2003, leg. A.E.Z. Short, AS-03-002 (9, SEMC) ; McMullen Co., Rt. 72 at Esperanza Creek , 31.vii.2003, leg. A.E.Z. Short, AS-03-009 (1, SEMC) ; Dimmit Co., Hwy 85,. 5 mi E. Drudage, 31.vii.2003, unnamed stream, AS-03-010 (1, SEMC) . Virginia: Albemarle Co., Ivy , vi.1933, leg. F.E. Winters (2, CAS) ; “ Richmond ” (2, CAS) ; Gloucester Co., 12.x.1973 (7, USNM) ; James City Co., 10.v.1973, leg. Matta (1, USNM) ; Nelson Co., 21.vii.1973, leg. Matta (1, USNM) ; Norfolk, 10.x.1972, leg. Matta (1, USNM) .

Differential diagnosis. Body size 5.0–6.0 mm. Elytra with ten rows of serial punctures which are typically impressed into distinct grooves. Abdominal ventrites uniformly very dark brown to nearly black; pubescence short, and densely and evenly distributed. Aedeagus ( Figs. 7 C–E) 2.0 to 2.2-times longer than its greatest width; apex of parameres rounded ( Figs. 7 C–D) to truncate ( Fig. 7E ), with outer corners rounded; inner corners of apex of parameres forming an acute angle; lateral outer margins of parameres diverging on apical half; median lobe with apex gradually tapering to a blunt point.

This species only potentially co-occurs with H. normatus in the southwestern edge of its range, from which it can be distinguished by the more densely pubescent abdominal ventrites, the form of the aedeagus, and the more impressed elytral serial punctures. However, the latter character is somewhat variable in both H. maculicollis and H. normatus and should not be used alone to separate the species where both may co-occur.

Distribution. Eastern United States ( Fig. 10 ). Here we present new state records for Pennsylvania, Kansas, Iowa, and Maryland. In addition to states for which we examined material, there are also published records from North Carolina and Delaware ( Hansen 1999, Short 2005). The species is not known from Canada, New England, or the Great Lakes region and likely does not occur there.

Interestingly, this species and the other North American species ( H. normatus ) seem to exhibit mutually exclusive ranges ( Fig. 10A ). There seems to be a contact zone in central and southern Texas which delimits an eastwest break in the distributions of these taxa.

Biology. This species is found in a variety of habitats but seems to prefer the margins of ponds and lakes, although it has also been found along the slack water margins of streams and rivers. Based on personal observations (AEZS), the species tends to occur in open, sunny areas with mud substrates and some vegetation. This species has been observed to carry its egg case.

Remarks: While this species appears morphologically homogeneous, it exhibits very high levels of genetic divergence. All three populations that were sequenced in this species (from Florida, Kansas, and Texas) exhibited between 8 and 10% divergence in COI. This is a rather extreme amount of intraspecific variation relative to other species of aquatic beetles that have been studied (e.g. Bergsten et al. 2012, Kohlenberg & Short 2017). Additional investigation may reveal this taxon to be composed of several cryptic species across its range.

The syntypes of H. bipunctatus Sharp from Mexico and Guatemala had previously been synonymized by d’Orchymont (1943) with H. maculicollis . This view was also taken by Short (2005) based primarily on the impressed elytral serial punctures. However, as more material has been examined, this character is not as decisive in separating species as it first appeared. Unfortunately, both syntypes are females, and so the aedeagus cannot be used to establish identity. We prefer to treat this synonymy as uncertain until the syntypes can be further studied and/or genetic material from southern Mexico and Guatemala can be obtained. We consider this is especially prudent as other specimens known from Central America cluster with H. normatus .

Figures

FIGURE 3. Dorsal habitus images of Helochares (Hydrobaticus) spp. (A) H. maculicollis (Pennsylvania), (B) H. normatus (California), (C) H. normatus (California, lighter form), (D) H. normatus (Arizona).

FIGURE 5. Heads of Helochares (Hydrobaticus) spp. (A) H. maculicollis (Pennsylvania), (B) H. normatus (California), (C) H. normatus (Arizona), (D) H. nexus n. sp., (E) H. zamora n. sp., (F) H. trujillo n. sp., (G) H. championi, (H) H. sp. A., (I) H. politus n. sp.

FIGURE 6. Abdomens of Helochares (Hydrobaticus) spp. (A) H. normatus, (B) H. maculicollis, (C) H. nexus n. sp. (Panama, ventrites paler on lateral thirds), (D) H. nexus n. sp. (Panama, uniformly pale ventrites).

FIGURE 7. Aedeagi of Helochares (Hydrobaticus) spp. (A) H. trujillo n. sp., (B) H. zamora n. sp., (C) H. maculicollis (Florida), (D) H. maculicollis (Kansas), (E) H. maculicollis (Pennsylvania), (F) H. nexus n. sp. (Venezuela), (G) H. nexus n. sp. (Panama), (H) H. nexus n. sp. (Ecuador), (I) H. politus n. sp., (J) H. laevis n. sp., (K) H. championi.

FIGURE 10. Distribution of New World Helochares (Hydrobaticus) spp.