Cybister (Neocybister) festae Griffini, 1895

Miller, Kelly B., Michat, Mariano C. & Ferreira Jr, Nelson, 2024, Reclassification of Cybistrinae Sharp, 1880 in the Neotropical Region (Coleoptera, Adephaga, Dytiscidae), with description of new taxa, ZooKeys 1188, pp. 125-168 : 125

Cybister (Neocybister) festae Griffini, 1895

Figs 9 , 15 , 16 , 30-32 , 51 , 58 , 72

Cybister festae Griffini, 1895: 1.

Cybister (Meganectes) festae : Brinck 1945: 18.

Cybister (Neocybister) festae : Miller et al. 2007: 54; Nilsson and Hájek 2023: 84.

Type locality.

Panama, Darién, Matusagrati Lake (Laguna della Pita).

Type specimens.

The syntype specimens are in Museo Regionale di Scienze Naturali di Torino (Museum of Turin, MRSN) (Fig. 72 ). Images of the specimens were examined (Fig. 72 , courtesy of F. Giachino, MRSN). Two specimens are included in the type series, a male and a female (Fig. 72 ; Griffini 1895). Neither are dissected. The male specimen is here designated as the lectotype to stabilize the nomenclature of the species (see Material examined below; Fig. 72 ). Although the male is not dissected and the genitalia were not examined, the specimens agree well with the others examined for this study in size, shape, coloration, distribution, and other features.

Diagnosis.

This species differs from the other Neotropical Cybister species, C. puncticollis , in smaller size (TL = 20.3-21.7 mm in C. festae vs. 26.6-27.6 mm in C. puncticollis ) and the shape of the male genitalia. The male median lobe in C. puncticollis is apically broadly expanded (Fig. 34 ) whereas in C. festae the median lobe is apically less strongly expanded with lateral margins that are somewhat more parallel-sided (Fig. 31 ). The specimens examined match the description of C. festae , but it is possible that the species illustrated and described here is not the same as C. festae since the lectotype (in MRSN) was not dissected.

Description.

Measurements. TL = 20.3-21.7 mm, GW = 11.7-13. mm, PW = 8.8-9.2 mm, HW = 5.1-5.5 mm, EW = 2.9-3.0 mm, TL/GW = 1.7-1.8, HW/EW = 1.7-1.8, WC/WV = 4.3-4.4. Body shape oval, widest slightly posteriad of middle; lateral margins broadly curved, continuously curved between pronotum and elytron. Depressed and somewhat flattened in lateral aspect.

Coloration. Head dark green-black, clypeus and labrum pale yellow. Pronotum dark green-black, with broad lateral yellow marginal band, medial margin of band distinctly delimited, band separated from posterolateral margin by narrow green strip (Fig. 9 ). Elytron dark green-black with broad lateral yellow marginal band, medial margin of band distinctly delimited, lateral margin of band slightly remote from lateral elytral margin for medial portion of length, extending laterally to margin of elytron anteriorly and posteriorly, apex of yellow band diffusing into coloration of elytron (Fig. 9 ). Ventral surfaces mostly black except antennae and palpi orange, pro- and mesothoracic legs with basal segments (trochanter and femur) pale orange and apical segments (tibia and tarsus) testaceous, metathoracic legs with mix of testaceous and orange, propleuron and elytral epipleuron pale orange to testaceous, and with small orange maculae laterally on abdominal ventrites IV-VI.

Sculpture and structure. Head broad, anteriorly produced, eyes prominent; dorsal surface evenly covered with exceptionally fine micropunctures but appearing smooth and shiny. Pronotum with lateral margins evenly and shallowly curved; surface of pronotum similar to surface of head in micropunctation; pronotum dorsally evenly curved. Elytron with margins very broadly curved, more strongly curved posteriorly; surface similar to surface of head in micropunctation and surface appearance. Prosternal process anteriorly rounded, surface nearly flat throughout and moderately broad, apex broadly elongate and sharply pointed. Metaventral wing narrow (WC/WV = 4.3-4.4); surface smooth, with extremely fine microsculpture, shiny. Lateral portion of metacoxa large, broad, surface smooth and shiny, with extremely fine microsculpture; metacoxal lines short and strongly curved, well-incised, extending anteriorly less than half distance across metacoxa. Abdominal ventrites smooth, unsculptured.

Male genitalia. Male median lobe in lateral aspect slender throughout length, apically slender, straight, and apically pointed, dorsal sclerite slender, evenly curved basally, apically straight, and slender, (Fig. 30 ); in ventral aspect broad basally, laterally somewhat constricted medially, apically broadly truncate (Fig. 31 ). Lateral lobe slender broad basally, apically strongly narrowed and slender, with long dorsal series of setae (Fig. 32 ).

Female genitalia (Fig. 58 ). Gonocoxosternite moderately broad, basal portion broadly ovate; gonocoxae together knifelike, evenly convergent to apex; rami smooth, short; vagina elongate; spermatheca elongate, ~ 2/3 length of vagina.

Sexual dimorphism. Males have a broad protarsal palette with ventral adhesive setae with apical structures in the form of elongate flattened spatulate surfaces; males also have mesotarsomeres with posteroventral fields of setae which are absent in females. Females lack natatory setae along the ventral margins of the metatarsomeres, but these are present in males. Males have a single metatarsal claw (the anterior, Fig. 15 ), whereas females have a second posterior claw that is ~ 2/3 length of the anterior, curved, and apically sharp (Fig. 16 ).

Variation. Two specimens were examined, a male and a female. The female has the extent and intensity of greenish-rufous coloration somewhat greater than the male and is larger, but otherwise the two specimens are similar.

Distribution.

This species is known from the type locality in the Darién in Panama ( Griffini 1895; Brinck 1945) and Venezuela, Apure State (new country record).

Material examined.

The lectotype (here designated) in MRSN is labeled, "Laguna d. Pita (Darien) [handwritten]/ Cybister festae ♂ Griffini tipo./ Cybister festae (tipo) Griffini Darien [green label, black line border, horizontal black lines)." Other than the type specimens (not directly examined), two specimens were examined from Apure State, between La Ye and Bruzual, Venezuela from a roadside lake (7.6443333 -69.3000667) (SEMC, accession numbers: SEMC0846768, SEMC0846766) .

Figures

Figure 72. Cybister (Neocybister) festae, lectotype male (left) and paralectotype female (right). Photograph courtesy of F. Giachino, MRSN.

Figures 9 - 14. Neotropical Cybistrinae species, habitus 9 Cybister festae 10 Cybister puncticollis 11 Nilssondytes diversus 12 Megadytes parvus 13 Megadytes latus 14 species " IR 57 " (Ribera et al. 2008). Scale bar: 10.0 mm.

Figures 15 - 29. Neotropical Cybistrinae species, metatarsal claws and tarsomere VI of males and females 15, 16 Cybister festae 17, 18 Cybister puncticollis 19, 20 Nilssondytes diversus 21, 22 Megadytes latus 23, 24 Megadytes parvus 25 species " IR 57 " (Ribera et al. 2008) 26, 27 Paramegadytes glaucus 28, 29 Metaxydytes fraternus. Scale bars: 1.0 mm.

Figures 30 - 50. Neotropical Cybistrinae species, male genitalia 30 - 32 Cybister festae: 30 median lobe, right lateral aspect 31 median lobe, ventral aspect 32 right lateral lobe, right lateral aspect 33 - 35 Cybister puncticollis: 33 median lobe, right lateral aspect 34 median lobe, ventral aspect 35 right lateral lobe, right lateral aspect 36 - 38 Nilssondytes diversus: 36 median lobe, right lateral aspect 37 median lobe, ventral aspect 38 right lateral lobe, right lateral aspect 39 - 43 Megadytes parvus: 39 median lobe, right lateral aspect 40 median lobe, ventral aspect 41 right lateral lobe, right lateral aspect 42 apex of median lobe, right lateral aspect 43 apex of median lobe, ventral aspect 44 - 47 Megadytes latus: 44 median lobe, right lateral aspect 45 median lobe, ventral aspect 46 right lateral lobe, right lateral aspect 47 apex of median lobe, ventral aspect 48 - 50 species " IR 57 " (Ribera et al. 2008): 48 median lobe, right lateral aspect 49 median lobe, ventral aspect 50 right lateral lobe, right lateral aspect.

Figures 51 - 57. Neotropical Cybistrinae species, male sternite IX, ventral aspect 51 Cybister festae 52 Cybister puncticollis 53 Nilssondytes diversus 54 Megadytes latus 55 Megadytes parvus 56 Paramegadytes glaucus 57 Metaxydytes fraternus. Scale bars: 1.0 mm.

Figures 58 - 61. Neotropical Cybistrinae species, female genitalia including left gonocoxosternite, ventral aspect, except Fig. 60 without internal genitalia 58 Cybister festae 59 Cybister puncticollis 60 Megadytes latus 61 Nilssondytes diversus. Scale bars: 1.0 mm.