Limnocoris zacki Rodrigues & Sites, 2019

Rodrigues, Higor D. D. & Sites, Robert W., 2019, Revision of Limnocoris (Heteroptera: Nepomorpha: Naucoridae) of North America, Zootaxa 4629 (4), pp. 451-497 : 489-494

Limnocoris zacki Rodrigues & Sites NEW SPECIES

( Figs. 1A , 2B, 2D , 18 , 19 G–H, 20B)

Description. Male—hindwing brachypterous. HOLOTYPE, length 5.84; maximum width 4.24. Paratypes (n = 10), length 5.68–6.32 (mean = 6.07); maximum width 4.16–4.40 (mean = 4.28). General shape rounded to oval; widest across posterior region of embolia. Overall dorsal coloration brown to dark brown, hemelytral membrane slightly darker, mottled on head, pronotum, and hemelytra ( Fig. 18A ). Dorsal surface with fine granulations and punctate throughout. Ventral coloration brown to dark brown.

Head. Head length 1.22, maximum width 2.04. Mostly medium brown with posterior region dark brown, punctate ( Fig. 18A ). Synthlipsis 1.08; eyes not raised above level of vertex or pronotum. Anterior margin between eyes convex, extending anteriorly 19% of head. Maxillary plate tumescent anteriorly. Labrum width 1.2× length, distolateral margins convergent to broadly rounded apex. Labium with three visible brownish segments, darkening distally, extending 0.32 beyond labrum not including extruded stylets. Antenna, length 0.46; not exceeding lateral margin of eye; pedicel quadrate; flagellomeres slender, partially fused, with long setae. Postgenal tubercle on posteroventral midline.

Thorax. Pronotum ground color brown, rectangular area behind eyes darker, lateral margins light brown; other smaller dark brown markings generally dispersed; transverse sulcus marking anterior border of transverse band in posterior 1/4; anterior margin concave between eyes; lateral margins convergent anteriorly, evenly convex; posterior margin almost straight, shallowly concave medially; posterolateral corner rounded ( Fig. 18A ); greatest width 3.3× length at midline; length at midline 1.14; maximum width at posterolateral corner 3.78. Prothorax ventrally dark brown medially, light brown laterally ( Fig. 18B ). Propleuron with pubescent area distinctly extended posteriorly along lateral margin; posterior margin straight ( Fig. 1A ); posteromesal corner near prosternellum deflexed ventrally. Probasisternum with median carina bilobate in lateral view, and divided in two posteriorly. Scutellum punctate; triangular; reddish brown, darker at anterolateral corners, light brown on posterior corner; width 2.00, length 1.00. Hemelytra punctate, brown to dark brown, with darker and lighter markings throughout, mostly on corium; membrane darker and mottled ( Fig. 18A ); length 4.44 (chord measurement). Embolium greatest width 0.58, lateral margin convex, light brown in anterior 3/4 and brown posteriorly. Hindwings reduced. Region between mesobasisternum and mesoepisternum without longitudinal row of elongate golden setae. Mesosternal carina with median ridge between anterior projection and fossa increasing in size to acute projection at anterior end of fossa ( Fig. 18E ); fossa partially open anteriorly, shape roundedly quadrate to oval ( Fig. 18C ). Metasternal carina with fossa oval to teardrop-shaped, slightly depressed medially ( Fig. 18C ); posterior margin excavated in lateral view ( Fig. 18E ).

Legs. All legs segments medium brown to light brown, except dark brown apical part of tarsomere III of middle and hind legs ( Fig. 18B ). Procoxa with cluster of stout, brown anteromedial spines. Profemur anterior margin with dense pad of setae without associated spines, posterior margin with row of short brown spines along basal half. Protibia and tarsus with occlusal inner surface flattened; tarsus one-segmented, immovable; pretarsal claw single, minute, triangular. Meso- and metacoxae partially recessed into thorax ( Fig. 18B ). Meso- and metafemora with row of short, brown spines on anterior margin. Meso- and metatibiae with ventrolateral, ventromedial, dorsolateral, and dorsomedial rows of stout brownish spines; meso- and metatibiae with two transverse rows of spines distally, one on lateral and another on mesal margins. Meso- and metatibiae and metatarsus with long, pale swimming hairs, hairs profuse on metatibia and –tarsus. Meso- and metapretarsi with paired claws slender, gently curved, with minute basal tooth. Leg measurements as follows: fore leg, femur 1.48, tibia 1.00, tarsus 0.38; middle leg, femur 1.62, tibia 1.20, tarsomeres 1–3, 0.12, 0.30, 0.41; hind leg, femur 2.06, tibia 2.08, tarsomeres 1–3, 0.12, 0.70, 0.68.

Abdomen. Dorsally with lateral margins of terga III–VIII exposed; terga III–V dark brown anteriorly, light brown posteriorly ( Fig. 18A ); marginal row of short yellow setae, and group of trichobothria near posterolateral corners. Lateral margin of abdomen with minute serration. Posterolateral corners of II–V narrowly rounded to right angled, not spinose. Sterna brown ( Fig. 18B ), covered by golden pubescence, without generally dispersed elongate golden setae; sternum II with irregular patch of elongate golden setae. Mediotergite VI with accessory genitalic process poorly developed ( Fig. 19G ). Mediotergite VII posterior margin with rounded, inconspicuous posterolateral corners and a rounded central lobe; lateral lobe with lateral margins parallel, posterior margin rounded ( Fig. 19G ). Lateral lobe of tergum VIII with lateral margin shallowly concave in anterior half; left medial lobe angled laterally at apex, with distal margin truncate; right medial lobe twisted in distal third; mediosternite VIII with medial notch on posterior margin ( Fig. 18B ).

Female—hindwing brachypterous. Paratypes (n = 10), length 5.88–6.56 (mean = 6.16); maximum width 4.24–4.64 (mean = 4.42). Similar to male in general structure and coloration, except as follows: Abdominal tergum VI symmetrical. Subgenital plate width 1.02× length; length at midline 0.82; maximum width 0.84; lateral margins converging in apical 3/4 to broadly rounded apex, without tuft of elongate golden setae at mid-length ( Fig. 18D ); laterosternite VII acuminate posteriorly; laterosternite VIII with posterior margin truncate to convex.

Diagnosis. Specimens of L. zacki n. sp. are small, measuring 5.84–6.56. The pubescent area of the propleuron is distinctly extended posteriorly along the lateral margin and the posterior margin of the propleuron is straight at mid-length ( Fig. 1A ). The mesosternal carina has a distinct projection between the anterior projection and fossa, and a small aperture at the anterior region of the fossa. The male abdominal mediosternite VIII has a medial notch on the posterior margin.

Comparative notes. Limnocoris zacki n. sp. is similar to L. insularis , L. lutzi , and L. nanus n. sp. These species are similar in size and morphology, including the pubescence pattern of the ventral surface. The primary character to distinguish among these species is the mesosternal carina; L. zacki is unique with a distinct projection between the anterior projection and fossa, and a small aperture at the anterior region of the fossa.

Distribution. This species is distributed from southern Mexico (Chiapas) to northwestern Guatemala (Huehuetenango and Suchitepequez) ( Fig. 20B ). It probably also occurs in El Salvador and Honduras. Additional field surveys in these countries are needed.

Etymology. The specific epithet honors the American entomologist Richard S. Zack (Washington State University), who has conducted extensive fieldwork in Guatemala and kindly made specimens available to us for study.

Type material examined. HOLOTYPE brachypterous ♂: MEXICO, Chiapas, Mpio. Ángel Albino Corzo, Jaltenango, Río Jaltenango ( Río Lagartero ), 6 January 2012, 605 m, 15°52’33.7”N / 92°43’53.4”W, riffles & marginal vegetation, D. Reynoso-Velasco, L-1313 ( UMC) . PARATYPES: same data as holotype (1♂, 6♀, UMC; 1♀, MZUSP—all brachypterous); same but 7 January 2012, L-1314 (10♂, 9♀, UNAM; 10♂, 8♀, all brachypterous, 1♀ macropterous, IEXA); Km 30 fm Jaltenango to Siltepec , Plan de Ayutla , El Plan de Río Ayutla , 19 May 2012, 846 m, 15°42’23.6”N / 92°34’43.7”W, D. Reynoso-Velasco, L-1346 (1♂, 3♀, all brachypterous, UMC) . GUATEMALA, Huehuetenango, Dept. Rio Nenton ca 8 Km NE of La Laguna, 10 May 2013, 15.79915°N / 91.88951°W, 613 m, R.S. Zack collector (1♂, 1♀, UMC; 1♂, MZUSP; 1♂, 2♀, WSU—all brachypterous) . Suchitepequez, District Finca los Tarrales ca 12 Km N of Patulul, 6 June 2005, 14°31’37”N / 91°08’17”W, 750 m, small stream, R.S. Zack coll (1♂ macropterous, UMC) .

Figures

FIGURE 1. Structures of Limnocoris. (A–D) Propleuron, white arrows indicate posterior end of pubescent area, yellow arrows indicate mid-lateral region of posterior margin, (A) L. zacki n. sp., (B) L. inornatus, (C) L. virescens, (D) L. chaetocarinatus n. sp. (E–H) Part of abdominal segments, showing pubescence patterns of sternum II (circled), (E) L. moapensis, (F) L. submontandoni, (G) L. nanus n. sp., and (H) L. stali. pa = pubescent area, pra = pruinose area.

FIGURE 2. (A–B) Lateral view of meso- and metasternal carinae, (A) L. pygmaeus, white arrow indicates anterior projection, black arrow indicates excavation posterior to fossa, (B) L. zacki n. sp., black arrow indicates median projection of mesosternal carina. (C–D) Ventral view of meso- and metasternal carinae, (C) L. inornatus, white arrow indicates row of longitudinal golden setae between mesobasisternum and mesoepisternum, (D) L. zacki n. sp., white arrow indicates fossa partially open anteriorly, dotted lines indicate anterior and posterior limits of fossa. (E–F) Ventral view of abdominal segments III–V, (E) L. virescens, black arrows indicate posterolateral corners, (F) L. panamensis. (G–H) Ventral view of female abdominal segments IV–IX, (G) L. moapensis, sgp = subgenital plate, (H) L. major n. sp., white arrows indicate elongate golden setae, gs= posterolateral elongate golden setae on lateral margin of subgenital plate.

FIGURE 18. Limnocoris zacki n. sp. (A) Dorsal habitus and (B) ventral habitus of male holotype, hindwing brachypterous (UMC), with detail of notch at posterior margin of abdominal sternum VIII, (C) ventral view of part of head and thorax, (D) terminal abdominal sterna of female, and (E) lateral view of meso- and metasternal carinae. Size bar = 1.00 mm and applies only to Figs. A–B.

FIGURE 19. Structures of male terminalia. (A, C, E, G) 6th and 7th abdominal terga, (B, D, F, H) 8th abdominal tergum. (A–B) Limnocoris pygmaeus, (C–D) L. signoreti, (E–F) L. virescens, and (G–H) L. zacki n. sp.

FIGURE 20. (A–B) Distribution records for species of Limnocoris in North America.