Yara marmontsedu, Reyes & Espinoza & Girón, 2019

Reyes, Scarleth Margarita Raudez, Espinoza, Roberto Antonio Cano & Girón, Jennifer C., 2019, A new species and immature stages of the skiff beetle genus Yara Reichardt and Hinton (Coleoptera: Myxophaga: Hydroscaphidae) from Nicaragua, Zootaxa 4544 (1), pp. 125-134 : 127-133

Yara marmontsedu n. sp.

Figs. 1–47 .

Type material. Holotype (male): “ NICARAGUA / Pijibay Creek / Municipality of La Libertad / Chontales Department / 2012-13. In a shallow environment with grasses and clay. Col. Scarleth Ráudez / Roberto Cano and Rafael Varela”. (CIRA/ UNAN).

Paratypes (39): NICARAGUA: La Libertad: same data as holotype (7 males, 6 females; all cleared and mounted in microscope slides; CIRA / UNAN); (10 males, 10 females, preserved in glycerol, SEMC; 3 males, 3 females, preserved in glycerol, USNM) .

Differential diagnosis. Body length, females (1.20–1.37 mm) and males (1.20–1.47 mm); hindwings welldeveloped; femoral plate of metacoxae triangular, extending beyond area of articulation with metatrochanter, almost covering the metatrochanter completely; metatrochanter with three thick spines along inner margin; female abdominal tergite and sternite VIII with a median apical emargination; median lobe of aedeagus nearly 1.5× longer than basal apophysis; basal apophysis of aedeagus bifurcate near base.

Yara marmontsedu n. sp. resembles Y. dybasi Reichardt & Hinton , mostly because of characters of the abdominal apex of females. Both species can be distinguished by the development of the hindwings (welldeveloped in Y. marmontsedu n. sp.; reduced in Y. dybasi Reichardt & Hinton ), the size of the femoral plate (large in Y. marmontsedu n. sp., see Figs. 7 , 16 ; short (as in the original generic diagnosis) in Y. dybasi Reichardt & Hinton ), and the presence of three distinct spines along the inner margin of the metatrochanter in Y. marmontsedu n. sp. (with a row of long setae, as in the generic diagnosis in Y. dybasi Reichardt & Hinton ). Furthermore, the form of the aedeagus of Y. marmontsedu n. sp. is similar to the form in Y. maculata Short, Joly & García (J-shaped at base), except by the basally bifurcated basal apophysis in Y. marmontsedu n. sp. (apically bifurcated in Y. maculata Short, Joly & García , see Fig. 6 in Short et al. 2010).

Description. Body, elongated, fusiform, with dense setae all over the surface ( Figs. 1–6 ). Body length 1.20– 1.37 mm in females, 1.20–1.47 mm in males. Head. Prognathous, transverse, nearly 2× wider than long. Eyes not protruding from outline of head ( Figs. 4 , 7 ); dorsal surface of head microreticulate, with sparse, rather long fine setae; frontoclypeal suture well defined, bell-shaped. Clypeus yellowish, reticulated, with abundant fine setae. Labrum with dorsal surface coarsely reticulated, bearing a transverse row of rather long and thick setae at midlength ( Fig. 7 ); ventral edge of labrum ( Fig. 11 ) fringed by stout setae, bearing lateral tufts of fine long setae; hypopharynx ( Fig. 11 ) as a median longitudinal tuft of fine setae. Mandibles ( Fig. 10 ) with well-developed mola, a median tuft of fine setae, and two teeth (apparently three) on the incisor region, with proximal tooth bifurcated. Antennae with eight antennomeres ( Fig. 7, 8 ); antennomere I 1.6× longer than antennomere II; antennomeres III– VII subquadrate, similar in size and shape to each other, nearly as long as wide, half as long as antennomere II; antennomere VIII somewhat wedge-shaped, 1.4× longer than antennomere I. Maxillary palps ( Fig. 9 ) with four palpomeres; palpomere III thicker than palpomere II, palpomere IV short, digitiform, bearing a lateral and an apical sensilla. Mentum ( Fig. 12 ) well-developed, subquadrate, with a basal row of six long setae. Prementum ( Fig. 12 ) well-developed, with two transverse rows (preapical and apical) of subquadrate teeth, laterally limited by one spiniform tooth and a seta on each side. Labial palps ( Fig. 12 ) with two palpomeres; palpomere II digitiform, with an outer basal sensillum and a group of apical sensilla, central apical sensillum digitiform, largest. Thorax. Pronotum trapezoidal in dorsal view, with posterior margin as wide as base of elytra ( Figs. 1, 4 ). Elytra dark brown with yellow markings: an irregular area on basal third, a small median spot at 2/3, and an apical transverse band; elytra densely covered by long setae on dorsal surface; each elytron 1.5× longer than wide, with anterolateral corner rounded, truncated at apex, covering up to basal half of third abdominal tergite ( Figs. 1, 4 ); ventral surface with long setae along lateral and posterior margins. Hindwings well-developed (examined in 14 individuals; Fig. 13 ), each 2.3× longer than wide, densely covered by short setae over entire surface, and fringed by long setae along margins, except antero-basal (costal) margin; anal lobe well-developed. Legs ( Figs. 14–16 ). All femora with a row of setae along dorsal margin; all tibiae with a row of spines along ventral margin, mesotibia with additional row of well-developed spines along dorsal margin; metacoxae with long, triangular femoral plate ( Figs. 7 , 16 ), partly covering metatrochanter, extending beyond area of articulation; metatrochanter ( Fig. 16 ) with three rigid and thick spines along posterior margin; all tarsi with three tarsomeres ( Figs. 14–16 ); tarsal claws long and thin ( Figs. 14– 16 ). Abdomen. Abdominal segments of both males and females moderate and rather uniformly covered by setae ( Figs. 1–6 ); tergite IV lacking dense cover of setae; tergite III light brown, tergites IV and V dark brown, tergite VI and VII yellowish; tergite VIII of females ( Figs. 4, 5 , 17, 17a ) conical, yellowish along basal and apical fourths, dark brown along mesal region, with apical margin mesally emarginate; tergites VIII and IX of males ( Figs. 1, 2 , 19, 19a ) conical, tergite VIII with narrow yellowish bands along basal and apical margins, dark brown along mesal region; sternite VIII of males with apex asymmetrically projected ( Fig. 20, 20a ), bearing three thick, curved setae along left side of projection. Female genitalia with two long lateral cylindrical projections extending beyond last tergite ( Figs. 17, 17a, 18, 18a ); both projections similar in length, covered by setae, with two long preapical setae. Aedeagus ( Fig. 21 ) with median lobe slender, non-coiled, at most J-shaped at base ( Figs. 21, 22 ); median lobe nearly 1.5× longer than basal apophysis; basal apophysis bifurcated near its base ( Fig. 23 ).

Larva. Body fusiform in dorsal view ( Fig. 26 ), slightly compressed dorsoventrally ( Fig. 27 ), with abdominal segments gradually decreasing in width towards apex ( Figs. 26–28 ); body 0.95–1.4 mm in length, light to dark brown in coloration; surface of body tuberculate and rather densely covered by thick and rather long, curved setae (e.g. Fig. 24 ). Head ( Fig. 28 ) transverse, nearly 2× wider than long; postero-dorsal margin of head slightly emarginate, postero ventral margin strongly emarginate. Stemmata relatively large, each well defined, six on each side; each group of stemmata abruptly projecting from the surface of the head capsule, bearing a well-developed central seta. Antennae ( Fig. 30 ) nearly as long as stemmatal tubercle; antennal insertions projected as tubercles; basal antennomere cylindrical, nearly as wide as long; apical antenommere with two branches, one of them bifurcate at apex. Frontoclypeal suture indistinct. Labrum ( Fig. 29 ) semirectangular, with posterior margin rounded, and a row of tiny denticles along median region of ventral apical margin which is bordered by paired larger teeth. Ventral mouthparts exposed, well-developed ( Fig. 29 ). Maxillary palps well developed ( Fig. 33 ), each with two elongated palpomeres; palpomere II with an apical seta. Labium ( Fig. 31 ) subquadrate, nearly as long as wide, with two rows of tiny irregular denticles along apical margin, bordered by paired larger teeth; each labial palp with one single palpomere ( Figs. 29, 31, 32 ). Thorax about half as long as abdomen ( Fig. 26 ); posterior margin of each thoracic tergum fringed by rather long and thick setae. Legs ( Figs. 36–38 ) slender, each pair separated by nearly the width of a coxa ( Fig. 28 ); femora slightly longer than tibiotarsus, pretarsus nearly 0.7× as long as tibiotarsus. Abdominal segments II to VII with lateral projections posteriorly directed; each projection with apical curved and thick setae ( Fig. 34 ); abdominal tergite VIII with apical margin fringed by setae ( Fig. 35 ); sternite VIII with paired hook-like spines ( Fig. 35 ).

Distribution. Pijibay Creek, La Libertad Municipality, Chontales Department, Nicaragua (12°12' N, 85°10' W; Figs. 43–47 ).

Etymology. The specific epithet marmontsedu is formed by the abbreviation of the names of the three children of authors Raudez and Cano: Margarita, Montserrat and Eduardo, to whom the species is lovingly dedicated.

Natural history. Adult specimens were collected during the wet season (October) in 2012 and in the dry season (April) of 2013 at the margins of Pijibay Creek. Ovigerous females were found during the dry season (April 2013). Each female contained between 1 and 3 eggs ( Fig. 24 ). The eggs are elliptical, 2.4× longer than wide (length: 199.8±9.5µm; width: 81.9±6.39µm; n = 8), light brown in color with smooth surface ( Fig. 25 ); each egg is slightly longer than abdominal segments II and III of the female combined ( Fig. 24 ). Larvae and a pupa were collected during the wet season. The larvae described here are likely on the last larval instar, given their strong resemblance to the adults. The head of the larva is also generally similar to the head of third instar Hydroscapha natans as described by Beutel & Haas (1998). The pupa was brown in coloration and covered by a membrane ( Figs. 39–42 ); unfortunately, only one pupa was collected, and given its condition we are not able to describe it in detail.

The site is characterized by shallow waters (less than 1 m deep), with permanent flow. The dominant materials of the creek bed are silt and clay, resulting in a muddy substrate devoid of rocks or sand; the marginal areas of the creek are covered with grassland vegetation and limited riparian shrubs ( Figs. 43–47 ).

According to the physicochemical parameters measured, Pijibay Creek has permanent flow of well oxygenated water in both wet and dry seasons (5.3 ± 0.5 mg /L mean value; oxygen saturation: 64.2 ± 1.7%); the average temperature is 26 ± 0.6 °C; the electrical conductivity is low (51.3 ± 12.7 µS/cm), and the pH is slightly acidic (6.90 ± 0.57). All the parameters indicate that because of the moderate temperatures, slow flow of water, and moderate concentrations of oxygen, Pijibay Creek offers optimal conditions for the survival of aquatic life. Other groups of invertebrates sampled along with Y. marmontsedu n. sp. include, among others, certain members of the orders Ephemeroptera, Odonata, Plecoptera, Trichoptera, and other Coleoptera , generally associated with clean to moderately contaminated (elevated contents of organic matter) waters (e.g. Hanson et al. 2010).

Figures

FIGURES 1–6. Habitus of Yara marmontsedu: (1, 4) dorsal, (2, 5) lateral, (3, 6) ventral; male (1–3); female (4–6). Scale bar 0.5 mm.

FIGURES 7–12. Ventral view and head appendages of Yara marmontsedu: (7) ventral view of head and thorax, scale bar: 100 µm; (8) antenna, (9) maxilla, (10) left mandible, (11) ventral view of labrum including hypopharynx, (12) labium. Scale bars: 50 µm.

FIGURES 13–16. Hindwings and adult legs of Yara marmontsedu: (13) extended hindwing; (14) proleg; (15) mesoleg; (16) metaleg. Scale bar: 0.1 mm.

FIGURES 17–25. Abdomen of Yara marmontsedu: (17) female abdomen, dorsal view, black arrow indicates emargination on apical margin of tergite VIII; (17a) same, line drawing; (18) female abdomen, ventral view, black arrow indicates emargination on apical margin of sternite VIII; (18a) same, line drawing; (19) male abdomen, dorsal view, black arrow indicates emargination on apical margin of tergite VIII; (19a) same, line drawing; (20) male abdomen, ventral view, black arrow indicates emargination on apical margin of sternite VIII, white arrow pointing curved setae; (20a) same, line drawing; (21) aedeagus; (22) basal apophysis in lateral view; (23) basal apophysis in dorsal view; (24) ventral view of ovigerous female; (25) egg. Scale bar: 17–20: 0.1 mm.

FIGURES 26–38. Larva of Yara marmontsedu: (26) dorsal view; (27) lateral view; (28) ventral view; (29) ventral view of head; (30) antenna; (31) ventral view of mandible, prementum and mentum; (32) detail of labial palp; (33) detail of maxilla including maxillary palp; (34) detail of lateral projection of abdominal segments; (35) detail of lateral view of last abdominal segments; (36) proleg; (37) mesoleg; (38) metaleg. Scale bars: 26–28: 0.5 mm; 29–33: 50 µm; 34–37: 0.1 mm.

FIGURES 39–42. Pupa of Yara marmontsedu: (39) dorso-lateral view; (40) detail of head and antenna; (41) detail of pretarsus; (42) detail of apex of abdomen.

FIGURES 43–47. Distribution and collecting: (43) map for species of Yara; (44) map for Central American species of Yara; (45) sampling locality at La Libertad, Chontales, Nicaragua; (46) Pijibay Creek; (47) collecting macroinvertebrates using a Dnet at Pijibay Creek.