Dineutus sublineatus (Chevrolat, 1834)

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 : 75-82

Dineutus sublineatus (Chevrolat, 1834) Figures 44, 45, 46, 54

Gyrinus sublineatus Chevrolat 1834: 3, Dineutes sublineatus : Brullé 1835: 240, Dineutes integer LeConte 1854: 221 [synonymy by LeConte 1861], Dineutus (Dineutus) sublineatus : Ochs 1926: 138, Dineutus (Protodineutus) sublineatus : Guignot 1950: 126, Dineutus sublineatus : Blackwelder 1944: 81, Dineutus (Cyclinus) sublineatus : Brinck 1955: 106, Dineutus sublineatus : Arce-Pérez and Roughley 1999: 84.

Type locality.

Mexico, Bocadelmonte.

Specimens examined.

326

Type material examined.

Dineutus sublineatus : not examined. The first author was unable to locate the syntype of Dineutus sublineatus Chevrolat after searching the MNHN with the assistance of A. Mantilleri.

Dineutus integer : syntype (♀ pinned) "Type/ 6092 [red label, Type typed in black ink, 6092 handwritten in black ink]// Dineutus integer / Webb Lec./ Copper Mines [white label, handwritten in black ink, handwriting appears to be LeConte’s]// sublineatus 2 [white label, handwritten in black ink, handwriting unknown]//" deposited in MCZ.

Material examined.

EL SALVADOR: Chalatenango: San Jose del Sacare, 15.iii.1927, leg. R.A. Stirton (2 ex. KSEM). GUATEMALA: Baja Verapaz: 15 km N Salama, 5.vi.1991, leg. J.E. Wappes (1 ex. FSCA). HONDURAS: Comayagua: Malootal Minas de Oro, v.1932, leg. J.B. Edwards (1 ex. KSEM). MEXICO: Aguascalientes: Sierra Fria ca. 40 mi SW Rinconde Romos, 2438 m, 11.iii.1953, leg. I.J. Centrall, #55 (2 ex. FSCA); Baja California Sur: Bahía Concepción, “Lanito”, 15 m, 16.iv.1968, leg. M.E. Irwin (1 ex. UCRC); Sierra Laguna, 17 air mi ENE Todos Santos, 1829 m, 12-18.xii.1979 EMEC 204906-204907 (2 ex. EMEC); Sierra Laguna, 17 mi ENE Todos Santos, 12-18.xii.1979, leg. J. Doyen, W. Tschinkel, EMEC 204770-204771; EMEC 204793-204799; EMC 204811-204815; EMEC 204817-204823; EMEC 204827-204849; EMEC 204860 (47 ex. EMEC); Arroya Posa ca. 10 mi W Loreto, 183 m, 6.vi.1978, leg. C.M. Murvosh & R.K. Allen, EMEC 654702-654710 (9 ex. EMEC); 9 mi WSW Loreto, Arroyo Las Parras, 207 m, 10.vii.2004, leg. W.D. Shepard, EMEC 204602-204619 (18 ex. EMEC); 9 mi SW Loreto, Arroyo Las Parras, 250 m, 20.vii.2004, leg. W.D. Shepard, EMEC 204620-204644 (25 ex. EMEC); 0.6mi S San Javier, 387 m, 20.vii.2004, leg. W.D. Shepard, EMEC 204668-204669 (2 ex. EMEC); Ram di Naran Rd., 10-28k W Rt 1, 28-31.viii.1994, leg. J.E. Wappes (1 ex. FSCA); 4.3 km E La Burrera, 550 m, 11-14.x.1978, leg. Dezier & Westcott, canyon-stream (1 ex. FSCA); Chihuahua: 3 mi NW Chihuahua, 20.viii.1952, leg. J.D. Lattin, S. Weitsman, EMEC 204861 (1 ex. EMEC); 15 mi E Cuauhtemoc, Black & White lights, 2012 m, 11.vii.1964, leg. J.A. Chemsak & J. Powell, EMEC 204916 (1 ex. EMEC); 13 mi E Cuauhtamoc, Black & White lights, 2012 m, 11.vii.1964, leg. J.A. Chemsak & J. Powell, EMEC 204825 (1 ex. EMEC); Hidalgo, 25 mi W Del Parral, Black & White lights, 2073 m, 15.vii.1964, leg. J.A. Chemsak & J. Powell, EMEC 204904 (1 ex. EMEC); Hidalgo, 25 mi W Parral, Black & White lights, 2073 m, 15.vii.1964, leg. J.A. Chemsak & J. Powell, EMEC 204824 (1 ex. EMEC); Chihuahua, 1524 m, 4.ix.1963, leg. H.V. Weems Jr., collected at light (1 ex. FSCA); Chiapas: El Zapotal, 2 mi S Tuxtla Gutierrez, 15.vii.1956, leg. J.W. MacSwain, D.D. Linsdale, EMEC 204888; EMEC 204892 (2 ex. EMEC); El Chorreodero, 600 m, 15.v.1991, leg. J.D. McCarty, EMEC 204645 (1 ex. EMEC); Simojovel, 1-16.viii.1958, leg. J.A. Chemsak, EMEC 204759; EMEC 204909 (2 ex. EMEC); Coahuila: 1 mi SE Saltillo, at blacklight, 23-26.ix.1976, leg. J.A. Chemsak & J.A. Powell, EMEC 204792 (1 ex. EMEC); Durango: Nombre de Dios, 25.vi.1952, leg. E.E. Gilbert, C.D. MacNeil, EMEC 204859; EMEC 204911-204915 (5 ex. EMEC); 6.3 mi N Nombre de Dios, 1829 m, 25.vi.1952, leg. R.F. Smith, EMEC 204910 (1 ex. EMEC); Guerrero: Mochitlan, Acahuizotla, Bosque tropical bajo caducifolio, 750 m, 11.vii.1986, leg. L. Delgado (1 ex. FSCA); Zumpango del Rio, 2.xi.1943, leg. E.K. Waering (1 ex. FSCA); Jalisco: Puerto Los Mazos, 9mi SW Autlan, 27.viii.1970, leg. M.S. & J.S. Wesbauer, EMEC 204776; EMEC 204780-204785 (7 ex. EMEC); 6 mi W Chapala, 30.vi.1963, leg. J. Doyen, EMEC 204790; EMEC 204787-204788 (3 ex. EMEC); Rio de Tepospisaloya, ca. 6 km N Union de Tula, 9.2 km W Tacotán, 20°03.86'N, 104°20.91'W, 381 m, 10.i.2005, leg. C.B. Barr, EMEC 654701 (1 ex. EMEC); México: NE of Temescaltepec, Canubi a Chichotla, 2027 m, 23.iv.2004, leg. W.D. Shepard, EMEC 204600-204601 (2 ex. EMEC); Michoacán: 26.7 km N La Huacana, 18.vii.1989, leg. R. Brooks, A. Roig, (1 ex. KSEM); Morelos: Alpuyeca, 3.vii.1951, leg. P.D. Hurd, EMEC 204757 (1 ex. EMEC); Nuevo León: 15 mi W Linares, 27.viii.1969, leg. J. Haddock, J.T. Doyen, EMEC 204774-204775 (2 ex. EMEC); 4 mi W of El Cercado, 6.vi.1951, leg. P.D. Hurd, EMEC 204758 (1 ex. EMEC); 4 mi S of Monterrey nr Siesta Motel, 6.vii.1963, leg. R.H. Arnett Jr., E.R. VanTassell, Lot No. V-56 (1 ex. FSCA); same as previous except: 7.vii.1963, Lot No. V-58 (8 ex. FSCA); 3.9 km NE Iturbide, ex: stream, 1410 m, 24.iii.1991, leg. Brooks, Leschen, #62 (1 ex. KSEM); 37 km SW Linares, 4.8 km S on Bosque Esquela Rd., ex:pool, 1545 m, 20.iii.1991, leg. Brooks, Leschen, #13 (1 ex. KSEM); 10 mi W of Cola del Caballo Falls, 24.xii.1972, leg. J.C. Schuster (2 ex. FSCA); Nayarit: 7mi N Tetitlan, 14.vi.1962, leg. D.H. Janzen, EMEC 204746-204751; EMEC 204754-204755; EMEC 204767; EMEC 204850-204852; EMEC 204854-204855; EMEC 204862-204865; EMEC 204869-204880; EMEC 204882-204883; EMEC 204885-204886; EMEC 204898; EMEC 204922-204924 (38 ex. EMEC); La Mesa de Nayar, 19.vii.1955, leg. B. Malkin, EMEC 204867-204868; EMEC 204887; EMEC 204889-204891; EMEC 204893; EMEC 204895-204896; EMEC 204899-204905; EMEC 204914 (16 ex. EMEC); Sierra de Zapotan, iii.1943, leg. E. Paredes, Pool in stream (3 ex. FSCA); Sierra Zapotan, 1300 m, iii.1943, leg. E. Paredes (2 ex. UCRC); 24 mi SE Tepic, 1045 m, 22.vi.1968, leg. A.R. Hardy, L. Espinosa, J.P. Abrayaya (1 ex. UCRC); Oaxaca: 4 mi W Tehuantepec, 21.vii.1952, leg. E.E. Gilbert, C.D. MacNeil, EMEC 204763-204766 (4 ex. EMEC); Oaxaca, ix.1957 (1 ex. FSCA); same as previous except: 28.ix.1957 (1 ex. FSCA); same as previous except: 29.ix.1957 (4 ex. FSCA); 33 mi W of Tehuantepec, 762-914 m, 22.viii.1963, leg. H.V. Weems Jr., in pool in mt. stream (12 ex. FSCA); Puebla: 11 mi SE Acatlan, 10.vii.1952, leg. E.E. Gilbert, C.D. MacNeil, EMEC 204760; EMEC 204762 (2 ex. EMEC); 45 mi N Acatan, 30.vii.1963, leg. J. Doyen, EMEC 204789; EMEC 204791 (2 ex. EMEC); 3 mi NW Petlalcingo, 1402 m, 29.viii.1972, leg. Byers & Thornhill (1 ex. KSEM); Sinaloa: 21 mi E Ville Union, Black & White lights, 91 m, 25.vii.1964, leg. J.A. Chemsak & J. Powell, EMEC 204816 (1 ex. EMEC); 36 mi N of Mazatlan, 18.xi.1955, leg. J.C. Schaffner (1 ex. FSCA); Sonora: 7 mi W Alamos, Blk- & White lights, 8.viii.1964, leg. J.A. Chemsak, J. Powell, EMEC 204810; EMEC 204826 (2 ex. EMEC); 5 km N Alamos, 6.viii.1998, leg. M.S. Caterino, EMEC 204768 (1 ex. EMEC); 7 mi SE Alamos, 27.xi.1970, leg. K. Stephan (1 ex. FSCA); nr Guicochi, 1768 m, 25.i.1972, leg. V. Roth (1 ex. FSCA); Veracruz: Laguna Verde, 30.iii.1975, leg. C. Halffter, P. Reyes, BLT (2 ex. FSCA). U.S.A.: Arizona: Cochise Co., SW Reg. Sta., 5 mi SW Portal, 4.viii.1961, leg. J.M. Linsley, EMEC 204884 (1 ex. EMEC);1 mi up CarrCyn R., 9.vii.1972, leg. J.M. Cicero (2 ex. FSCA); 6 mi E Bisbee, 17.vii.1972, leg. J.M. Cicero, (1 ex. FSCA); Skeleton Canyon, 24.viii.1962, leg. D. Weems (1 ex. FSCA); Skeleton Canyon, 1372-1524 m, 24.viii.1962, leg. H.V. Weems Jr. (1 ex. FSCA); Cave Creek Canyon, 11.vii.1984, UVL (1 ex. FSCA); Coronado Ntl. For., Idlewild cmpgd, 18.v.1990, leg. R.S. Miller (1 ex. MTEC); Huachuca Mtns, Bear Cr., rock pools in strm, 31°22'24"N, 110°21'40"W, 26.iv.2000, leg. K.B. Miller, #2000-12 (1 ex. MSBA); Rucker Canyon, pools in strbed, 25.iv.2000, leg. K.B. Miller (1 ex. MSBA); Hidalgo Co., Skeleton Canyon, Peloncillo Mts., 1372-1524 m, 25.viii.1962, leg. H.V. Weems Jr., in stream (1 ex. FSCA); Pima Co., Tucson, v.1958, leg. L. Lenando (2 ex. MTEC); Tucson, 2.viii.1970, leg. K. Stephan (1 ex. FSCA); Tucson, Sabino Canyon, 29.v.1958, leg. L. Lenando (1 ex. MTEC); Mouth of Madera Canyon, 17.vi.1967, leg. B. Streit (7 ex. FSCA); Madera Canyon, 22.ix.1977, leg. R.S. Miller (1 ex. MTEC); Catalina Mts., 4.viii.1930, leg. L.K. Gloyd, 145 (4 ex. FSCA); Sabino Canyon, 22.viii.1968, leg. F. Hovore, 489-490 (2 ex. FSCA); Box Spring Canyon, 8.viii.1986, leg. R.S. Miller (1 ex. MTEC); same as previous except: 9.viii.1986 (1 ex. MTEC); same as previous except: 10.viii.1986 (1 ex. MTEC); Sta. Rita Exp. Range, 04.viii.1988, leg. S. Lajeunesse (1 ex. MTEC) same as previous except: leg. M.M. Hooten (1 ex. MTEC); Coronado Ntl. For., 6.ix.1938, leg. C.L. Hubbs family, 102b (1 ex. FSCA); Santa Catalina Mtns., Molino Canyon, 3.iii.1968 (5 ex. FSCA); same as previous except: 30.iii.1969 (1 ex. FSCA); Santa Cruz Co., Peña Blanca, 24.viii.1977, leg. R.S. Miller (2 ex. MTEC); same as previous except: 20.viii.1971, leg. J. Cicero (2 ex. FSCA); same as previous except: 16.vii.9172 (1 ex. FSCA); Peña Blanca Lake, 10.x.1990, leg. W.B. Warner (2 ex. FSCA); Peña Blanca Lake, 20.vii.1982, leg. G.H. Nelson, Ultraviolet light (2 ex. FSCA); Madera Canyon,15.vii.1972, leg. J. Cicero (2 ex. FSCA); Sycamore Canyon, 16.iv.1950, leg. R.R. Miller & H.E. Winn, M-50-40 (1 ex. FSCA); Mt. Hopkins, 27.vii.1992, leg. J.&M. Huether (1 ex. FSCA); Spring fed trib. to Peña Blanca Canyon, 17.iv.1950, leg. R.R. Miller & H.E. Winn, M50-41 (1 ex. FSCA); Santa Rita Mts., Gardner Canyon, 22.vi.1975, leg. K. Stephan (2 ex. FSCA); New Mexico: Hidalgo Co., Peloncillo Mtns., Clanton Canyon, pool in wash, 20.ix.2009, leg. A.B. Johnson et. al. (3 ex. MSBA); Texas: "Big Bend", vii.1960, leg. D. Thornton (3 ex. FSCA); John Davis Co., Valentine, 13.vii.1927, leg. L.A. Anderson (2 ex. KSEM); Kerr Co., Kerrville, 2.vii.1938, leg. I. Norris (2 ex. FSCA).

Diagnosis.

Male (Fig. 44C-D): Size: 12.3-15.5 mm. Body form elongate broadly oval; elytral apices broadly or flatly rounded/subtruncate, with serrations and irregularities absent apically, apicolateral sinuation weakly present, each elytron with all 9 elytral striae well developed, elytral stria 1 and 2 often obscured suturally and near the scutellar region by dense microreticulation, often accompanied by fine weakly impressed punctures; profemora with highly acute sub-apicoventral tooth; protibiae club-shaped; mesotarsal claws similar in size with very weak denticle (Fig. 45C) venter darkly colored, usually black to dark reddish brown, mesothoracic and metathoracic legs usually lighter in coloration, as well as apex of abdomen; Aedeagus (Fig. 45A, B, D) median lobe in dorsal view nearly as long as parameres, narrow, becoming attenuated apically, apex very narrowly rounded, in lateral view median lobe becoming highly narrowed ventrally in apical 1/3, shallowly curved dorsally after basal 1/3, ventrally median lobe with parallel sided sperm-groove, parameres in dorsal view very weakly expanded laterally at apical 1/3, angled apically.

Female (Fig. 44A-B): Size: 12.6-14.0 mm. Body form regularly oval; elytral apices broadly or flatly rounded/subtruncate, with serrations and irregularities absent apically, apicolateral sinuation usually weakly present, each elytron with all 9 elytral striae well developed, elytral stria 1 and 2 often obscured suturally and near the scutellar region by dense microreticulation, often accompanied by fine weakly impressed punctures; profemora without sub-apicoventral tooth; protibiae club-shaped; venter darkly colored, usually black to very dark brown, mesothoracic and metathoracic legs usually lighter in coloration, as well as apex of abdomen, abdominal sternite VII with medial expansion of posterior margin.

Differential diagnosis.

Dineutus sublineatus is unique among all North American Dineutus in being large in size, with a more or less regularly elongate oval body form, with all 9 elytral striae strongly evident, males with a small well developed and highly acute profemoral sub-apicoventral tooth, the form of the aedeagus (Fig. 45A), and females with abdominal sternite VII (Fig. 44B) with a medial expansion of the posterior margin. This species is highly unique in having the elytral striae well developed and highly evident. All other species have the elytral striae primarily faintly evident, or apparent but not strongly developed. All 9 elytral striae are evident, and often for most their length. Striae 1 and 2 can be obscured near the scutellar region as well as the near the sutural region of the elytra, by the microreticulation of these areas, which is often accompanied by fine weakly impressed punctures. An even more unique character of this species is the medial expansion of the posterior margin of abdominal sternite VII in the female. This is unique among the females of all Ne World Dinuetus . This species is similar to other Mexican and Central American species in coloration, being dorsally olive green with light violet reflections laterally on the elytra, and with the venter being very darkly colored black to reddish brown. However, Dineutus sublineatus unlike the other large Mexican and Central American species has the elytral apices regularly to flatly rounded/subtruncate, as opposed to being truly truncate.

Distribution

(Fig. 54C). Extreme southwestern U.S., throughout most of Mexico and central Central America to Nicaragua ( Blackwelder 1944; Leech 1948; Ochs 1949; Régimbart 1882; 1907; Roberts 1895; Wood 1962).

Habitat.

Lotic and lentic. In Oaxaca, Mexico, 43 mi w of Tehuantepec Dineutus sublineatus was collected in pools in mountain streams at 2500-3000 ft in elevation (FSCA). Other label data also indicate pools in steams. In the United States the second author has collected this species in pools in dry streambeds within canyons in southern Arizona.

Discussion.

There is dimorphism in body form among the sexes of Dineutus sublineatus . Females tend to be more evenly elongate regularly oval, while males have a greater dorsoventral convexity in the scutellar region (especially evident in lateral view) resulting in a steepness in the humeral region of the elytra and the posterolateral region of the pronotum. Males of Dineutus sublineatus also have the lateral margin, just posterior to the humeral region of the elytra, slightly expanded. As mentioned earlier females also have a medial exspansion of abominal sternite VII, not seen the males.

This species exhibits a large amount of variation throughout its range, with noticeable variation in body form. A series of specimens from near Tehuanatepec, Oaxaca, Mexico, has the females noticeably smaller than the males, and much more parallel sided in appearance, as well as both sexes with the elytral apices very flatly rounded, nearly truncate in appearance. A single female specimen from Salama, Guatemala (Fig. 46C) (UCRC), was observed with a highly parallel sided body form, with the elytral apices seemingly produced, and very flatly rounded. This specimen at first glance seemed like a different species, but the specimen possesses the well-developed elytral striae and abdominal sternite VII with a medial expansion, currently characteristic of only Dineutus sublineatus . Without a male to unambiguously place the Guatemalan specimen as a different species, we considered it a variation of Dineutus sublineatus , as it possessed the diagnostic females character of the medial expansion of abdominal sternite VII, thus far unique to Dineutus sublineatus .

Specimens from Siera de Zapotan, Narayit, Mexico (Fig. 46A) (UCRC), show variation in the punctation of the elytra, being composed of large shallowly impressed punctures, giving the elytra a dimply appearance. This situation is also seen in specimens from this locality in Dineutus solitarius (Fig. 46B). Other variation in the sculpturing of the elytra can be seen in several different populations. Some populations have the cells of the reticulation of the pronotal disc, as well as the elytral disc near the scutellar and sutural region, noticeably reflective, creating a bright metallic green color.

Even though there is a great deal of variability in these species in terms of body form, elytral apices, and elytral sculpturing, several characters are very stable. These include the strong development of the elytral striae in both sexes, in males the form of the aedeagus, and in females abomdinal sternite VII possessing a medial expansion. There is very minimal varation in the form of the male aedeagus, which is the most diagnostic character for species recognition within Dineutus .