Dineutus productus Roberts, 1895

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 : 60-62

Dineutus productus Roberts, 1895 Figures 33, 34, 54

Dineutes productus Roberts 1895: 282, Dineutus (Cyclinus) productus : Ochs 1926a: 137.

Type locality.

USA, Texas.

Specimens examined.

17

Type material examined.

Syntype (♂ pinned) "Tex./Acc. 4858/Type productus, ♂type # 2, C.H.R./ Dineutus productus Roberts 1895 Det: L. Cook 2005" AMNH type Catologue 496.

Material examined.

U.S.A.: Kansas: Bourbon Co., Ft. Scott, ca. 2 mi NE, Marmaton River, "T25S R25Esec 20 NW 1/4", 4.viii.1976, leg. S. Hamilton, T. Oldham, SEMC 10549560 (1 ex. KSEM); Elk Co., Elk River at Elk Falls, 37.374416 -96.184123, 278m, 22.vi.2014, leg. C. Maier, C. Faris, S. Baca, G.Gustafson, GTG062214B (5 ex. GTGC), Elk River S. of Longton, 37.36960 -96.078735, 262m, 22.vi.2014, leg. C. Maier, C. Faris, S. Baca, G.Gustafson, GTG062214A (6 ex. GTGC); Greenwood Co., Lapland, 4mi S Fall River, east branch, 13.ix.1974, leg. D. Huggins, SEMC 1054959 (1 ex. KSEM); Lyon Co., Lyon Co.-Greenwood Co. line, Verdigiris River, "T21S R10E sec 36 SE 1/4", 16.vii.1976, leg. S. Hamilton, SEMC 1054955, SEMC 1054957 (2 ex. KSEM); Morris Co., Council Grove Lake, outflows and groves, 13.vi.1974, leg. T. Edmonds, SEMC 1054958 (1 ex. KSEM); Texas: “Sequin”, 26.vi.1938, leg. D.W. Craik (2 ex. KSEM).

Diagnosis.

Male (Fig. 33C, D): Size: 9.5-9.6 mm. Body form narrowly elongate oval; elytral apices rounded with sutural angle produced to a point, apicolateral sinuation weakly present, irregularities present apically near sutural production, elytral apices strongly deflexed, reticulation of pronotal and elytral discs strongly impressed, producing a bronzy appearance; elytral striae faintly evident, most evident on the subapicomedial portion of the elytral disc; profemora with a very small sub-apicoventral tooth, accompanied by a series of denticles extending proximad, associated with each posterior setigerous puncture of the profemora; protibiae subsinuate; mesotarsal claws (Fig. 34C) long and of similar size, with ventral margin straight; venter darkly colored, usually black to very dark bronzy-brown, with the tibiae and tarsi of mesothoracic and metathoracic legs usually lighter in coloration, as well as apex of abdomen; Aedeagus (Fig. 34A, B, D) median lobe in dorsal view noticeably shorter than parameres, weakly constricted just apicad to middle, acuminate in apical ca. 1/5, apex of acumination flatly rounded, in lateral view median lobe roundly curved dorsally, in dorsal view parameres sinuate laterally after basal 1/3, in apical 1/3 laterally expanded, apically strongly rounded.

Female (Fig. 33A, B): Size: 9.5-9.9 mm. Body form narrowly elongate oval; elytral apices angled towards very strong sutural production, apicolateral sinuation strongly present and with plica, irregularities present apically near sutural production, elytral apices strongly deflexed, reticulation of pronotal and elytral discs strongly impressed, producing a bronzy appearance; elytral striae faintly evident, most evident on the subapicomedial portion of the elytral disc; profemora without sub-apicoventral tooth; protibiae club shaped, with lateral margin round, weakly expanded apicaly; venter darkly colored, usually black to very dark bronzy-brown, with the tibiae and tarsi of mesothoracic and metathoracic legs usually lighter in coloration, as well as apex of abdomen.

Differential diagnosis.

Dineutus productus can be distinguished from all other North American Dineutus in males having the profemora with a small sub-apicoventral tooth, accompanied by a series of denticles that extend proximad, with each denticle being associated with a posterior setigerous puncture of the profemora, elongate mesotarsal claws of equal size, with straight ventral margins (Fig. 34C), and in the form of the aedeagus (Fig. 34A). The species most similar to Dineutus productus is Dineutus serrulatus analis . The nominal subspecies of Dineutus serrulatus serrulatus should not be confused with Dineutus productus in that it has a restricted range in Florida, and its elytral apices would not easy be confused with those of Dineutus productus , being regularly rounded, with a strong apicolateral sinuation in both sexes and the dorsum being polished black in appearance. Dineutus serrulatus analis on the other hand tends to be variable in the appearance of the elytra (Fig. 37A, C), with some members having the sutural angle produced and the dorsum with strong microreticulation giving the elytra and pronotum a polished bronzed appearance, similar in both respects to Dineutus productus .

Dineutus productus can generally be separated from Dineutus serrulatus analis in having a more elongate narrow body form (Fig. 33A, C), and being smaller in size. Dineutus productus is much more narrowly attenuated anteriorly, compared to Dineutus serrulatus analis , which is broader in body form and larger in size. The ventral coloration of Dineutus productus is most often black to very dark brownish red, and frequently accompanied by a bronzy metallic sheen, while the venter of Dineutus serrulatus analis is most often red in color, rarely appearing black and often lacking any metallic sheen. When more darkly colored Dineutus serrulatus analis is much more red in hue, compared to when Dineutus productus is more lightly colored, having a more brownish hue. A few specimens of Dineutus serrulatus analis examined from southeast Kansas had their venters truly black (KSEM) and for these specimens differences between the male secondary sexual characters as well as differences in the elytra allowed for unambiguous identification. The serration of the elytral apices differs between these two species. In Dineutus productus the apices of the elytra only have irregularities present, at most having round bumps that resemble highly reduced serration, while in Dineutus serrulatus analis the serration is present as distinct and fine points.

The males of Dineutus productus can easily be distinguished from those of Dineutus serrulatus analis in that the profemoral sub-apicoventral tooth is small and accompanied by a series of denticles that extend proximad, with each denticle being associated with a posterior setigerous puncture of the profemora, in Dineutus serrulatus analis there is a profemoral sub-apicoventral tooth as normal, but no accompanying series of denticles. This character appears unique to Dineutus productus among all of the North American Dineutus species. The mesotarsal claws also differ greatly between these two species. Dineutus productus males have the mesotarsal claws elongate with their ventral margins straight (Fig. 34C) and lacking a denticle, while in Dineutus serrulatus analis the mesotarsal claws are small, with their ventral margins curved and possessing a denticle (38F). The aedeagus is by far the most definite way to separate the two species. The aedeagus of Dineutus productus (Fig. 34A) has the median lobe shorter than the parameres, and strongly acuminate apically, with the parameres being sinuate after the basal 1/3 and laterally expanded in the apical 1/3, with the apices rounded. In Dineutus serrulatus analis the median lobe (Fig. 38A, D, H) is as long as the parameres, parallel sided for most its length, having only the apical 1/4 narrowed, with the parameres being parallel sided for most of their length, being only weakly expanded in the apical 1/3 and often obliquely truncate, or obliquely flatly rounded.

Females of Dineutus productus (Fig. 33A) can be distinguished from those of Dineutus serrulatus analis in having a much greater apicolateral sinuation of the elytra, the sinuation is so deep that a plica is formed, and the elytral apices have a much steeper angle towards the sutural production than in Dineutus serrulatus analis females (Fig. 37A), which have a much more shallow apicolateral sinuation and more rounded elytral apices. As mentioned earlier the elytra of Dineutus productus have irregularities present apically, but not fine serration, as seen in Dineutus serrulatus analis .

Distribution

(Fig. 54A). Central and south-central United States ( Roberts 1895), into northeastern Mexico ( Ochs 1949). As this species is so rarely collected, we list here the states and counties where it has been collected and the identification is not in question: USA: Kansas: Bourbon Co., Elk Co, Greenwood Co., Lyon Co., Morris Co. (this study); Texas: Bosque Co. [Clifton] ( Ochs 1929), Brazos Co. [College Station] ( Wood 1962), Comal Co. ( Wood 1962), Dallas Co. [Dallas County]( Ochs 1929), Dimmit Co. ( Wood 1962), Karnes Co. [Kenedy]( Wood 1962), Neuces Co. [Corpus Christi]( Wood 1962); Mexico: Nuevo Leon: Granja Rodriguez on the borders of the Rio Salado alt. 195m ( Ochs 1949).

Habitat.

Lotic species, the Kansas Biological Survey field notes (available at the KSEM) indicate the species was collected from slow moving, cool, mud bottomed streams, that were fairly wide. Gustafson et al. (2014) describe the habitat where Dineutus productus was recently collected in detail, accompanied by photos of the habitats. The species has also been taken at light traps placed at water level in the vicinity of rapids, on the borders of the Rio Salado, in Nuevo Leon, Mexico ( Ochs 1949).

Discussion.

Dineutus productus appears to be an uncommonly collected species and the reason for this is not exactly clear. Most species found in the United States are uncommon due to a narrow range of endemism (e.g. Dineutus robertsi and Dineutus angustus ), but material examined in this study, as well as records from the literature, suggest the range of this species is not as narrow as the previously mentioned species. Dineutus productus was originally described from Texas by Roberts (1895), and most records of this species come from this state ( Régimbart 1907; Ochs 1929; Wood 1962). Young (1954) claimed to have specimens from the panhandle of Florida, but Epler (2010) re-examined specimens in the FSCA identified by Young as Dineutus productus , finding them to belong to other species. Hatch (1925a) claimed to have collected the species from the Sangamon River near Decatur, Illinois. Ochs (1949) however, questioned the Illinois record as well as Régimbart’s (1907) from the Carolinas, stating all specimens identified as Dineutus productus from outside of Texas actually belonged to other species upon his examination. In the same paper Ochs (1949) extended the species range southward in to Neuvo Leon, Mexico.

Material examined for this study from Kansas (KSEM, GTGC), was undoubtedly Dineutus productus , confirming that the range of Dineutus productus extends at least that far northward. This adds credence to Hatch’s (1925a) record from Illinois. Furthermore, comparing images of the Sangamon River available online to those provided by Gustafson et al. (2014), they appear to be the same habitat. The first author was unable to locate Régimbart’s specimen of Dineutus productus within the MNHN, in order to confirm Régimbart’s 1907 record, but Dineutus productus was not listed as a species of Dineutus found in North and South Carolina by Sanderson (1982). Given this and the inability to locate the specimen of Régimbart’s from the Carolinas in his collection at the MNHN, we do not treat Régimbart’s 1907 record as a part of the species range. Ochs’ diagnosis of Dineutus productus (1949) matchs our own, therefore we accept his record for the species from Nuevo Leon, Mexico as representing the southern-most extreme for the range. As mentioned above, given the new Kansas records for the species and the habitat photos of the Sangamon River available online, we accept Hatch’s (1925a) record from Illinois, as the northern-most extreme for the species’ range.

Most works treating Dineutus productus only mentioned having examined a few specimens (i.e. small series at most, usually 4 specimens for most studies [ Roberts 1895; Régimbart 1907; Ochs 1929, 1949; Young 1954]). Recent collecting revealed that the species could be collected, albeit with much difficulty, which may explain this species rarity in collections ( Gustafson et al. 2014). Hopefully accurate information on indentifying this species, as well as modern information of habitat and distribution, will help this species become better known.