Cylloepus dimorphus Shepard, Sites, and Rodrigues, 2021

Shepard, William D., Sites, Robert W. & Rodrigues, Higor D. D., 2021, A New, Sexually Dimorphic Species of Cylloepus Erichson from Brazil (Coleoptera: Elmidae), The Coleopterists Bulletin 75 (1), pp. 270-274 : 271-274

publication ID 10.1649/0010-065X-75.1.270

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Cylloepus dimorphus Shepard, Sites, and Rodrigues

new species

Cylloepus dimorphus Shepard, Sites, and Rodrigues , new species ( Figs. 1–4 View Fig View Fig View Fig View Fig )

Description. Holotype male ( Figs. 1 View Fig , 2A View Fig , 3 View Fig ): Body with color generally brown; red-orange on middle of pronotum, elytral bases and carinae; testaceous on palps, labium, antennae, and tarsi; pronotum 1.0 mm long, 1.2 mm wide; elytra 2.6 mm long, 1.7 mm wide conjointly at posterior twothirds. Plastron on venter (except apical half of abdominal ventrite 5), elytral epipleura, and legs (except tarsi). Head with frons heavily setose; clypeus with coarser setae than on labrum; labrum and clypeus broadly rectangular; disc shiny, with scattered setae; labial palps with four palpomeres, with terminal segment broader than long, apically with white sensory area; maxillary palps with three palpomeres, terminal segment obliquely truncate, with white sensory area; one apical angle of each antennomere with stout, white setae. Antenna originating from inner margin of eye, with 11 antennomeres, antennomeres 8–11 wider than preceding antennomeres. Pronotum explanate laterally; with stout sublateral carinae; disc with two low, wide ridges surrounding an elongate oval depression; disc covered with scattered, yellow setae. Scutellar shield flat-topped, shiny, setose. Elytra coarsely punctate-striate; punctures separated by own diameter; first interval slightly raised; third interval strongly raised in basal one-fourth; sixth interval carinate, extending to two-thirds length of elytra; eighth interval carinate to near apex; lateral margin carinate; surface with yellow setae widely separate. Prosternum with process apically broadly pointed, sides thickly margined, margins beginning at middle anterior of coxae. Mesoventrite with disc depressed below levels of prosternum and 272 metaventrite, posterior border arcuate. Metaven- golden setae. Legs all similar and setose; pro- and trite depressed apically and medially; disc with mesocoxae globular, metacoxa transverse; tibiae short, oblique, round-topped ridges; median lon- with one cleaning fringe of very short setae; each gitudinal groove present; transverse grooves present tibia apically with two short, blade-like spines; just anterior to posterior margin; disc with scattered tarsomeres 1–4 with short, stout setae ventrally, claws slender. Abdomen with ventrite 1 depressed along middle, depression laterally margined by straight carinae that reach apical two-thirds, surface with plastron and scattered golden setae; ventrites 2–4 broadly transverse, plastron and setae as on ventrite 1; ventrite 5 trapezoidal ( Fig. 2A View Fig ), sloping in basal half, apical half with each side drawn out into lobe, basally with plastron mostly absent in middle, present on sides, disc shiny where plastron absent, setae on disc short, except long, golden setae scattered laterally on lobes, between lobes disc very depressed, flat-bottomed, heavily setose. Aedeagus ( Fig. 3 View Fig ) with basal piece open dorsally, closed ventrally, thickest apically, parallel-sided in dorsal view ( Fig. 3A View Fig ); parameres dorsally touching basally at mesal margins, then diverging gently in basal one-fourth, then diverging more strongly in apical two-thirds, lateral margins parallel, apices broadly rounded ( Fig. 3A View Fig ); in lateral view thickest basally, ventral surface flat in basal two-thirds then concave ( Fig. 3B View Fig ), in ventral view parameres broadly open, mesal margins meeting lateral margin in apical fourth; median piece as long as parameres, blade-like, wider basally then narrowing apically ( Fig. 3C View Fig ), apex slightly deflexed in lateral view, apex rounded.

Variation. Second male with pronotum 1.0 mm long, 1.2 mm wide; elytra 2.4 mm long, 1.6 mm wide conjointly.

Females (n = 3). Body ( Fig. 4 View Fig ) same as male except slightly larger and abdominal ventrite 5 differently shaped. Pronotum 1.3–1.4 mm long, 1.3–1.5 mm wide. Elytra 2.7–3.6 mm long, 1.6–1.8 mm wide conjointly at two-thirds length. Abdominal ventrite 5 ( Fig. 2B View Fig ) with plastron in basal half, plastron absent in apical half; without lateral lobes.

Diagnosis and Comparative Notes. The shape of abdominal ventrite 5 of the male is sufficient to distinguish C. dimorphus from all other congeners. The male genitalia resemble those of Cylloepus consobrinus Grouvelle , but the parameres of C. dimorphus do not enclose the median piece along its length, as in C. consobrinus . In the key to the Brazilian species of Cylloepus (Hinton 1945) , C. 274 dimorphus would key to Cylloepus typhon Hinton. DISCUSSION However, the parameres of C. dimorphus lack the laterally pointed apical tooth, the hind trochanters This new species now brings the number of deare not gibbous, and the hind femur is not apically scribed species of Cylloepus to 57, with 21 recorded curved. Females cannot currently be separated from Brazil. The gravelly stream habitat from which from females of other species unless there are the specimens were collected is typical for the genus. males present and only one species occurs at a No specimens were taken on Cachoeira Itaúna, the site. waterfall (L-1980) immediately upstream from the Etymology. The specific epithet dimorphus is reach where C. dimorphus was collected. Greek for “two formed”, referring to the different shapes of the last abdominal ventrites of the ACKNOWLEDGMENTS sexes. Distribution. Brazil. This species is known only The Enns Entomology Museum provided optical from the type locality. and computing resources for imaging the specimens. Type Locality. BRAZIL: Minas Gerais, stream Two reviewers are thanked for their suggestions which below Cachoeira Itaúna, ca 15 km SE of Baependi, improved the quality of the manuscript. 2 Dec 2016, 923 m, S22°2.537 ′ W44°49.211 ′. This is a shallow, brown water stream with the substrate consisting of gravel and sand, and the REFERENCES CITED margins are vegetated. Five photographs of the Hinton, H. E. 1940. A monographic revision of the type locality are available in the Locality Image Mexican water beetles of the family Elmidae . Database of Enns Entomology Museum, under Novitates Zoologicae 42(2): 217–396. Brazil, L-1981. Hinton, H. E. 1945. A synopsis of the Brazilian species of Type Material. Holotype male: “ BRAZIL: Cylloepus Er. ( Coleoptera , Elmidae ). Annals and Minas Gerais / stream below Cachoiera / Itaúna; ca. Magazine of Natural History (Series 11) 12(85): 43–67. 15 km SE of / Baependi / 2 Dec 2016 / colls. R. W. Polizei, T. T. S., and M. V. L. Barclay. 2019. The genus

Cylloepus Erichson, 1847 ( Coleoptera : Elmidae : Sites, H. D. D. Rodrigues; L-1981 // 923 m;

Elminae) new species and combinations. Zootaxa 22°2.537’ S / 44°49.211’W / gravel, sand, / vege- 4652(1): 93–100. DOI: 10.11646/zootaxa.4652.1.3. tated margins” ( MZUSP). Paratypes (4), same data as holotype (1♀, 1♂ UMC; 2♀, MZUSP) GoogleMaps . The ho- (Received 5 July 2020; accepted 28 December 2020. lotype is deposited in MZUSP. Publication date 20 March 2021.)


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