Limnocoris nanus 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 : 476-479

Limnocoris nanus Rodrigues & Sites NEW SPECIES

( Figs. 1G , 12 , 14 C–D, 20B)

Description. Male—hindwing brachypterous. HOLOTYPE, length 5.28; maximum width 3.92. Paratypes (n = 2), length 4.88–5.20 (mean = 5.04); maximum width 3.72–3.84 (mean = 3.78). General shape rounded to oval; widest across posterior region of embolia ( Fig. 12A ). Overall dorsal coloration ligth brown to dark brown, mottled on head, pronotum, and hemelytra; hemelytral membrane with some darker spots and other parts lighter than corium. Dorsal surface with fine granulations and punctate throughout. Ventral coloration brown to dark brown.

Head. Head length 1.10, maximum width 1.82. Mostly brown with medium-dark brown markings narrowing anteriorly, punctate. Synthlipsis 0.18; eyes not raised above level of vertex or pronotum. Anterior margin between eyes convex, extending anteriorly 18% of head length; posterior margin between eyes straight, not extending posteriorly ( Fig. 12A ). Maxillary plate tumescent anteriorly. Labrum width 1.2× length, distal margin convex to slightly tapered. Labium with three visible brownish segments, darkening distally, extending 0.36 beyond labrum not including extruded stylets. Antenna, length 0.42; not exceeding lateral margin of eye; pedicel quadrate; flagellomeres slender, partially fused, and with long setae. Postgenal tubercle on posteroventral midline.

Thorax. Pronotum ground color brown, rectangular marking behind eye slightly darker, lateral margin lightly brown to yellowish; other smaller dark brown markings dispersed; transverse sulcus marking anterior border of transverse band in posterior 1/4; anterior margin straight between eyes; lateral margins convergent anteriorly, evenly convex; posterior margin almost straight, shallowly concave medially; posterolateral corner rounded ( Fig. 12A ); greatest width 1.54× length at midline; length at midline 1.12; maximum width at posterolateral corner 3.44. Prothorax ventrally dark brown medially, medium brown laterally ( Fig. 12B ). Propleura with pubescent area distinctly extended posteriorly on lateral margin (as in Fig. 1A ); posterior margin straight medially; posteromesal corner near prosternellum deflexed ventrally. Probasisternum with median carina bilobed anteriorly in lateral view, and divided in two posteriorly. Scutellum punctate, triangular, brown, width 1.68, length 0.90. Hemelytra punctate, medium brown to dark brown, with darker and lighter markings throughout, mostly on corium; membrane mottled; length 3.92 (chord measurement). Embolium greatest width 0.58, lateral margin convex, light brown to yellowish in anterior 3/4 and brown posteriorly. Hindwings reduced. Region between mesobasisternum and mesoepisternum without longitudinal row of elongate golden setae. Mesosternal carina with ridge between anterior projection and fossa, with some golden setae; fossa shallow, elongate; lateral margins of fossa convergent and meeting posteriorly, open ended anteriorly; anterior ridge entering open anterior end of fossa; anterior ridge with fine sulcus on midline ( Fig. 12C ). Metasternal carina with fossa oval to teardrop-shaped ( Fig. 12C ), depressed medially; posterior margin excavated in lateral view ( Fig. 12E ).

Legs. All legs segments light brown to yellowish, except dark brown apical part of tarsomere III of middle and hind legs. 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. 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 1.32, tibia 0.94, tarsus 0.34; middle leg, femur 1.38, tibia 1.06, tarsomeres 1–3, 0.08, 0.22, 0.34; hind leg, femur 1.70, tibia 1.80, tarsomeres 1–3, 0.13, 0.54, 0.52.

Abdomen. Dorsally with lateral margins of terga III–VIII exposed; terga III–V brown on anterior 1/4, light brown posteriorly ( Fig 12A ); 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. 12B ), covered by golden pubescence, without generally dispersed elongate golden setae; sternum II with irregular patch of elongate golden setae ( Fig. 1G ). Mediotergite VI with accessory genitalic process poorly developed. Posterior margin of mediotergite VII with rounded, inconspicuous posterolateral corners and a broadly convex central lobe; lateral and mesal margins of laterotergite VII parallel, posterior margin rounded ( Fig. 14C ). 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 ( Fig. 14D ).

Female—hindwing brachypterous. Paratypes (n = 5), length 5.08–5.36 (mean = 5.22); maximum width 3.80– 3.90 (mean = 3.86). Similar to male in general structure and coloration, except as follows: Abdominal tergum VI symmetrical. Subgenital plate width 1.02× length; length at midline 0.80; maximum width 0.94; lateral margins converging in apical 3/4, without tuft of elongate golden setae at mid-length; posterior margin broadly to narrowly rounded ( Fig. 12D ); laterosternite VII acuminate posteriorly; laterosternite VIII with posterior margin truncate to rounded.

Female—hindwing macropterous. Paratype (n = 1), length 5.85; maximum width 3.90. Similar to hindwing brachypterous specimens in general structure and coloration, except as follows: claval and intraclaval sutures, and posterior margin of embolium distinct.

Variation. The mesosternal carina of three specimens deposited at the EMEC has a minute ridge entering the fossa, and the sulcus on the midline is absent.

Diagnosis. Specimens of L. nanus n. sp. are among the smallest of the genus, measuring 5.08–5.85 mm in length. 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. The mesosternal carina has the anterior projection distinctly developed, the fossa is uniquely shaped with the lateral margins convergent and meeting posteriorly, but open ended anteriorly with the anterior ridge entering the open anterior end of the fossa; the anterior ridge has a fine sulcus on the midline.

Comparative notes. Limnocoris nanus n. sp. is morphologically similar to L. insularis , L. lutzi , and L. zacki n. sp. These species are similar in the size and general morphology of the body, including the pubescence pattern of the ventral surface. The most obvious feature to distinguish among these species is the mesosternal carina, which in L. nanus is unique, with the longitudinal sulcus in the anterior ridge entering the open anterior end of the fossa.

Distribution. This species is distributed from northern Costa Rica (Guanacaste) to the central region of Panama (Coclé) ( Fig. 20B ). It was collected in localities with the elevation ranging from 320 to 1,371 meters.

Etymology. The specific epithet nanus (Latin) = small or short, refers to the total length of the body of this species, which is the smallest species of Limnocoris from North America.

Type material examined. HOLOTYPE brachypterous ♂: PANAMA, Canal Zone , Rio Juan Grande at km 2 on Pipeline Rd, elev 30 m, 5 Jan. 1993, coll. J.T. Polhemus, CL2784 ( UMC) . PARATYPES: same data as holotype (1♂, 4♀, all brachypterous, UMC) ; PANAMA, Coclé, 4.2 Km SSE Miraflores , unnamed stream, 376’, 30.VIII.2006, WDS-A-1722, William D. Shepard leg (1♀ macropterous, EMEC) ; PANAMA, I-11 (1♂, 1♀, all brachypterous, UMC) . COSTA RICA, Guanacaste, P. N. Rincón de la Vieja, small stream at Las Pailas Trail , 18.I.2000, C.B. Barr (2♂ brachypterous, EMEC) .

Additional material examined. COSTA RICA, Cartago, S. of Cartago, 18.VI.1932, 4.500 ft, B.S. Kaiser (1♂, 2♀, all brachypterous, EMEC) .

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 12. Limnocoris nanus n. sp. (A) Dorsal habitus and (B) ventral habitus of male holotype, hindwing brachypterous (UMC), (C) ventral view of part of thorax, arrow indicates fine sulcus on midline of anterior ridge, (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 14. Structures of male terminalia. (A, C, E) 6th and 7th abdominal terga, (B, D, F) 8th abdominal tergum. (A–B) Limnocoris moapensis, (C–D) L. nanus n. sp., and (E–F) L. panamensis.

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