Platynectes (Platynectes) agallithoplotes, Gustafson & Short & Miller, 2016

Gustafson, Grey T., Short, Andrew E. Z. & Miller, Kelly B., 2016, New species of diving beetles in the subgenus Platynectes s. str. from the Guiana Shield (Coleoptera: Dytiscidae: Agabinae), Acta Entomologica Musei Nationalis Pragae 56 (1), pp. 79-102 : 96-100

Platynectes (Platynectes) agallithoplotes sp. nov.

( Figs 13–15 , 20, 21 )

Type material. HOLOTYPE: J, “ VENEZUELA: Bolivar State / 7°29′47.3″N, 65°51′44.8″W, 45 m / 2 km E Rio Chucivero , 6.viii.2008 / leg. A.Short, M.Garcia, L.Joly / AS-08-075; rock outcrop seeps [white label, type black ink]” “SM0831494 / KUNHM-ENT [white label, typed black ink, with barcode]” ( MIZA) . PARATYPES (53 spec.): same holotype except: SM0828782–SM0828784, SM0831467–SM0831472, SM0831474–SM0831493 (29 spec. SEMC, MIZA, MALUZ) ; same state as holotype except: outcrop ca. 15 km NE Pijiguaos , N6°57.904′ W66°36.392′, 51 m, 9.vii.2010, leg. Short, Tellez, Arias, seeps, VZ10-0709-01 A, SEMC0909219 , SEMC0909228 (2 spec. SEMC) ; same as previous except: Los Pijiguaos at rock outcrop, N6°35.617′ W66°49.238′, 80 m, 9.vii.2010, leg. Short, Tellez, Arias, seeps and stream at night, VZ10-0709-03 A, SEMC0908746 , SEMC0908750 , SEMC0909094 (3 spec. SEMC) ; same as previous except:seep scrubbing, VZ10-0708-01C, SEMC0908718 (1 spec. SEMC) ; same as previous except: outcrop morichal, small stream on outcrop, VZ10-0708-01B, SEMC0907909 , SEMC0907910 , SEMC0907914 , SEMC0907916 , SEMC0907920 – SEMC0907923 , SEMC0907925 – SEMC0907928 (12 spec. SEMC) ; same state as previous except: Rock outcrop by morichal, N6°52.196′ W66°35.450, 75 m, 9.vii.2010, leg. Short, Tellez, Arias, seeps on outcrop, VZ10-0709-02 A, SEMC0911056 , SEMC0911061 , SEMC0911063 (3 spec. SEMC) ; “ Venezuela: Bolivar, Los Pijiguaos , outcrop/morichal, 60-80 m, 8.vii.2010, 6° 35′ 37.0212″N 66° 49′ 14.2788″W, Short, Arias, Tellez (VZ10-0708-01B) (ABTC2163)”, “MB 6289”, “MB 6290”, “MB 6291” (3 spec. ZSMG) .

Diagnosis. Small sized (5.2–5.8 mm in length), broadly oval, elytron with up to three yellow spots and a broad mostly apical lateral band.

Description. Size. Male: TL = 5.2–5.4 mm, TL-h = 4.8–5.2 mm, TW = 3.4–3.5 mm; female: TL = 5.4–5.8 mm, TL-h = 5.0– 5.3 mm, TW = 3.4–3.6 mm.

Body broadly oval, lateral margins evenly curved and continuous between pronotum and elytron (Fig. 14).

Coloration (Fig. 14). Head orange grading into diffuse, light yellow region medially on frons and testaceous to black mediad and posteriad of eyes, in some specimens extending anteriorly around eye to lateral margin of frons. Pronotum broadly black or testaceous medially along anterior and posterior margins, black regions meeting medially in lighter, testaceous transverse band; posterolateral margins of pronotum narrowly black, lateral surfaces yellow, extending medially to dark region; scutellum testaceous. Elytron dark testaceous dorsally, diffuse pale region at humeral angle which becomes continuous with apical pale band in some specimens, in others associated only with humeral yellow spot, additional less pale band present laterally, in less pale band dark spots evident representing elytral serial punctures, other elytral serial punctures more or less evident beneath testaceous region as dark spots, two well-demarcated yellow spots, one round parascutellar, one irregular humeral most often associated with lateral humeral pale band,

one highly variously developed yellow spot slightly posterior of middle near lateral margin, often absent in most specimens, when present normally round, rarely transverse,

apical band normally present often starting in apicolateral half of elytron, extending to apex, effaced prior to suture, replaced by testaceous band, in some specimens lateral pale band encompassing entire lateral region of elytra, joining with humeral pale band,

rarely apical pale band reduced to irregular anteapical spot. Appendages of head, and much of ventral surface, including elytral epipleuron, pale orange to yellow, tibia and tarsus of all legs darker in color, often light red, metaventrite, metacoxal wing, and ab- Fig. 14. Dorsal habitus of P. agallithoplotes sp. nov. Scale bar = 2 mm. domen distinctly infuscate.

Structure and sculpture. Head broad and short, anterior clypeal margin broadly rounded; anterior surface of frons and clypeus with fine, dense punctation, posterior surface of head with fine microreticulation of irregular cells, most cells also with fine punctures, antennae with antennomeres V–IX subserrate. Pronotum broad and short, medially often with small shallow dimple; lateral bead distinct and broad, evenly curved, about width of antennomere V; surface shiny, covered with fine microreticulation of large, irregular cells, cells with fine punctures, additional punctation consisting of a row of large coarse punctures on anterior and posterior margins, punctures separated by ca. 1–1.5× diameter of a puncture anterior, ca. 1–3× diameter of a puncture posteriorly, absent medially. Elytron broad, lateral margins evenly curved to slightly angulate apex, lateral epipleural carina distinctly visible throughout length; surface covered with weakly impressed, but distinct microreticulation of irregular cells, cells also with fine punctures; elytral epipleuron slender, evenly tapered to apex. Prosternum medially moderately long, longitudinally swollen; prosternal process broad, lateral margins broadly curved to somewhat pointed apex, surface flat to slightly curved, smooth. Metaventrite with anterior process broad, with broadly curved emargination for reception of prosternal process; lateral wings broad, WC/WS = 5; surface smooth, microreticulation weakly impressed, composed of short, irregular cells laterally, and more elongate cells medially, punctation nearly imperceptible. Fore- and midlegs slender, surfaces punctate, protibial apices with largest spine about as long as protarsomeres I–III combined; mesotibal apices with longest spine just shorter than mesotarsomeres I–III combined, mesotarsal spurs elongate slender, just longer than mesotarsomeres I+II; metacoxae smooth, fine reticulation composed of elongate cells, weakly impressed punctation present, punctures separated by ca. 1–2× diameter of a puncture, metacoxal lines distinct, broadly divergent anteriorly; hind legs slender, smooth, metafemur with fine reticulation composed of elongate cells, almost imperceptible weakly impressed punctation, few setigerous punctures on anterior surface of metatibia and metatarsomere I, metatrochanter apically spinous, metatibial spurs slender, anterior just shorter than metatarsus I, posterior longer than metatarsus I. Abdominal ventrites broad, smooth and unmodified, with fine reticulation composed of elongate cells, fine weakly impressed punctation, punctation nearly imperceptible.

Male genitalia ( Fig. 13 ). Median lobe in left lateral view weakly curved, strongly parallelsided, apically not expanded, slightly curved to rounded apex, dorsal surface with very small and weakly impressed pores, nearly imperceptible; ventral groove in right lateral view very narrow, even in width throughout its length.

Sexual dimorphism. There is noticeable sexual dimorphism with females on average larger and more elongate than males.

Variation. There was noticeable size variation, in general females were larger in size, but the largest male was comparable to the smallest female.

Differential diagnosis. Platynectes agallithoplotes sp. nov. is unique in terms of elytral maculation pattern having an apical pale transverse band in addition to three variously developed yellow spots (Fig. 14). The distinctly infuscate metacoxal process will also prevent confusion with any members of the P. submaculatus group as well as the P. nigerrimus group from more southern distributions in South America.

Etymology. The specific epithet is composed of agal- from the Greek agalliasis meaning great joy or exultation, - litho - Greek for stone, and - plotes being a noun derived from the Greek plotos meaning to swim: thus the specific epithet agallithoplotes meaning joyful- -rock-swimmer. This is in reference to the elytral maculae resembling a “smiley face” and hygropetric swimming behavior of specimens.

Natural history. This species has a more unusual habitat compared to the other known Guiana Shield species of the genus: all specimens have been collected in association with seepages on granite outcrops (e.g. Figs 20–21 ). During the day, individuals have been found hidden under detritus and rocks on the seepages, while adults have been observed swimming openly on the seepages. The putative larva of this species has also been collected on the seeps as well. In most cases, these seepages are seasonal and go completely dry for part of the year.

Distribution. The species is currently known from southern Venezuela ( Fig. 15 ).

Figures

Figs 7–13. Median lobe of aedeagus of Platynectes species, top row left lateral view, bottom row right lateral view. 7 – P. submaculatus (Laporte, 1835). 8 – P. elaskanaima sp. nov. 9 – P. meru sp. nov. 10 – P. decemnotatus (Aubé, 1838). 11 – P. garciai sp. nov. 12 – P. tafelbergensis sp. nov. 13 – P. agallithoplotes sp. nov.

Fig. 15. Distribution map of Platynectes species of northern South America.

Figs 20–21. Type locality and habitat of Platynectes agallithoplotes. 20 – Collecting Event AS-08-075 (Venezuela, Bolivar State, 2 km E Rio Cuchivero) showing seepage habitat on a granite outcrop. 21 – Same event, close-up of rock face with adult specimen swimming in the thin film of water.