Platynectes (Platynectes) tafelbergensis, 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 : 94-96

Platynectes (Platynectes) tafelbergensis sp. nov.

( Figs 4 , 12 , 15 , 18, 19 )

Type material. HOLOTYPE: J, “ SURINAME: Sipaliwini District / N3°53.942′ W56°10.849′, 733 m / CSNR: Tafelberg Summit, near / Caiman Creek Camp, small / streams with lots of plants & / leaf litter; leg. Short & Bloom / 18.viii.2013; SR13-0818-03 A [white label printed black ink]”, “ SEMC1233879 / KUNHM-ENT [white label with barcode at top, printed black ink]” ( NZCS) . PARATYPES (41 spec.): Same as holotype except: SEMC1233864 , SEMC1233865 , SEMC1233867 , SEMC1233868 , SEMC1233870 – SEMC1233875 , SEMC1233877 – SEMC1233878 , SEMC1233883 – SEMC1233885 (15 spec. SEMC, NZCS) ; same as previous except: forest detrital pools, SR13- 0818-2 A, SEMC1080445 (1 spec. SEMC) ; same as previous except: 19.viii.2013, SR13-0819-02 A, SEMC0966150 – SEMC0966157 (8 spec. SEMC) ; same as previous except: pooled up detrital forest stream, SR13-0819-05 A, SEMC1080404 (1 spec. SEMC) ; same as previous except: pools in forest, SR13-0819-05B, SEMC1233916 – SEMC1233922 , SEMC1233924 (8 spec. SEMC) ; same as previous except: forest detrital pools, SR13-0819-05C, SEMC1080494 (1 spec. SEMC) ; same as previous except: CSNR: Tafelberg Summit, nr Augustus Creek Camp, N3°55.600′ W56°11.300′, 600 m, 17.viii.2013, leg. Short & Bloom, small stream on trail to Caiman Creek Camp, SR 13-0817-02 A, SEMC1080668 , SEMC1080676 , SEMC1080678 (3 spec. SEMC) ; same as previous except:CSNR: Tafelberg Summit near South Rim , N3°53.359′ W56°10.052′, 879 m, 20.viii.2013, leg. Short & Bloom, small seep / streamlet, SR13-0820-01D, SEMC0930785 , SEMC0930786 (2 spec. SEMC) ; “ Suriname: Sipaliwini, Central Suriname Nature Reserve: Tafelberg Summit , near Caiman Creek Camp, 733 m, 18.viii.2013, 3° 53′ 56.5188″N 56° 10′ 50.9406″W, Short & Bloom (SR13-0818-03 A)”, “MB 6296”, “MB 6299” (2 spec. ZSMG) .

Diagnosis. Medium sized (5.8–6.5 mm in length), evenly oval in dorsal habitus, elytron with three yellow spots, two well-demarcated apically, one humeral variably developed.

Description. Size. Male: TL = 5.8–6.4 mm, TL-h = 5.3–5.8 mm, TW = 3.4–3.7 mm; female: TL = 5.9–6.5 mm, TL-h = 5.4–5.8 mm, TW = 3.6–3.8 mm.

Body evenly oval, lateral margins mostly evenly curved and continuous between pronotum and elytron, slightly laterally expanded at posterior 1/3 ( Fig. 4 ).

Coloration ( Fig. 4 ). 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 darkly colored, often black. Elytron testaceous to dark testaceous, with narrow, lateral diffuse pale band and two well-demarcated yellow spots, one slightly posterior of middle near lateral margin, and one anteapically, there is a third humeral spot that is variously developed, most often it is round and smaller than more apical spots, rarely irregularly shaped and equally well developed, and rarely so small as to be nearly absent. Appendages of head, legs and ventral surfaces, including elytral epipleuron, pale orange to reddish, somewhat darker on thoracic sterna and metacoxae; last abdominal tergite yellow.

Structure and sculpture. Head broad and short, anterior clypeal margin broadly rounded; entire dorsal surface of head with irregular cells, each cell with fine punctures, additional even covering of fine punctation throughout. Pronotum broad and short; 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 margin, punctures separated by ca. 0.5–1× diameter of a puncture anteriorly, ca. 2–3× posteriorly, absent medially. Elytron with lateral margins mostly evenly curved to slightly angulate apex, lateral epipleural carina distinctly visible throughout length; surface covered with weakly impressed, but distinct microreticulation of large 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 elongate cells, fairly even covering of fine punctaction, puncture separated by ca. 1–2× diameter of a puncture. Fore- and midlegs slender, surfaces punctate, protibial apices with several spines about length of protarsomeres I+II; mesotibal apices with longest spine just shorter than length of mesotarsomeres I+II, mesotarsal spurs elongate slender, slightly sinuate, as long as mesotarsomeres I; metacoxae smooth, fine reticulation composed of round cells, punctation fine and weakly impressed, punctures separated by ca. 4–5× 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, setigerous punctures on anterior surface of metatibia and metatarsomere I, metatrochanter apically spinous, metatibial spurs slender, anterior spur shorter than metatarsus I, posterior spur longer than metatarsus I. Abdominal ventrites broad, smooth and unmodified, with fine reticulation composed of elongate cells, punctation fine, punctures separated by ca. 3–4× diameter of a puncture.

Male genitalia ( Fig. 12 ). Median lobe narrow, in left lateral view strongly curved, apex very weakly expanded, dorsal surface sinuate, gradually constricted preapically, apex narrow, covered in pores in apical 2/3; ventral groove in right lateral view strongly narrowed apical 1/3, widened to 2× apical width in basal 2/3, apex with distinct flap.

Sexual dimorphism. Females appear to be slightly larger, both longer and broader, than males.

Variation. There is relatively little variation in size and shape, most being associated with sexual dimorphism.

Differential diagnosis. Platynectes tafelbergensis sp. nov. is most similar to P. garciai sp. nov. in elytral maculation pattern, having a relatively subdued maculation pattern with fewer than five yellow spots on each elytron, but differs in being smaller (body length = 5.8–6.5 mm), somewhat more parallel sided, and having much stronger apical maculae on the elytra ( Fig. 4 ). Having three elytral maculae, with the basal most pair situated at the humeral region while lacking parascutellar maculae, should generally prevent its confusion with any other species within the P. submaculatus group.

Etymology. This new species is named for the tepui, Tafelberg, in Suriname where the species was collected. Adjective.

Natural history. All collecting events from which this species is known were from stream- -associated habitats. Most specimens are from densely forested creeks and adjacent forest pools that contained a heavy load of detritus ( Figs 18–19 ).

Distribution. Only known from a few localities on the summit of Tafelberg in Suriname ( Fig. 15 ). Tafelberg is the easternmost as well as the most isolated of the Guiana Shield’s sandstone tepui formations.

Figures

Figs 1–6. Dorsal habitus of Platynectes species. 1 – P. meru sp. nov. 2 – P. decemnotatus (Aubé, 1838). 3 – P. elaskanaima sp. nov. 4 – P. tafelbergensis sp. nov. 5 – P. submaculatus (Laporte, 1835). 6 – P. garciai sp. nov. Scale bar = 2 mm.

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 16–19. Habitat of Platynectes species. 1 – Collecting Event AS-08-060b, Venezuela, Bolivar State: Rio Aponwao (P. garciai). 2 – Collecting Event SR10-0829-01A, Suriname, Sipaliwini District, along Sipaliwini River (P. decemnotatus). 3 – Collecting Event SR13-0819-05B, Suriname, Sipaliwini District, Tafelberg Tepui summit (P. decemnotatus, P. tafelbergensis). 4 – Collecting Event SR13-0819-02A, Suriname, Sipaliwini District, Tafelberg Tepui summit (P. tafelbergensis).