Deltochilum plebejum Balthasar, 1939

Figs 4 K – L, 7 A (red cross), 24, 25

Deltochilum (s. str.) plebejum Balthasar, 1939: 14.

Deltochilum plebejum: Génier 2001: 6.

Type material examined.

Lectotype (here designated) ♂ Venezuela: Maracaibo Basin, [10.455446]?, [- 71.787763]? E. Gevaerts / coll Valck Lucassen / Museum Leiden verz FT Valck Lucassen / Deltochilum (s. str.) plebejum sp. nov. Dr. V. Balthasar det / [red label] TYPUS / [red label] LECTOTYPE [male symbol] Deltochilum plebejum Balth. des. F. Z. Vaz-de-Mello, 2014 (RMNH). Paralectotype: ♀ Venezuela: Maracaibo Basin, [10.455446]?, [- 71.787763]? E. Gevaerts / coll Valck Lucassen / ex coll. V. Balthasar National Museum Prague, Czech Republic / Deltochilum spec.? det. Boucomont / [red label] TYPUS / [green label] plebejum m. / [yellow label] PARALECTOTYPE [male symbol] Deltochilum plebejum Balth. des. F. Z. Vaz-de-Mello, 2014 (NMPC).

Diagnosis.

This species shares the narrow striae and the apical tubercles of the elytra (on interstriae III, V, and VII) with D. nobile sp. nov. (Figs 23 C, 24 E), but it can be differentiated by the head punctures. The punctures on the anterior part of the head are nearly the same size as the head disc punctures in D. plebejum (Fig. 24 A), whereas they are larger in D. nobile sp. nov. (Fig. 22 A).

Redescription.

Female. Size 9.50 mm. Color. Pale reddish-brown dorsally. Dark greenish-blue ventrally. Head (Fig. 24 A). Interocular distance eight and a half times the width of one eye. Punctures on frons separated by less than one diameter of each puncture and slightly larger than the head discal punctures. Disc punctures separated by one or more than one diameter of each puncture. Punctures from disc towards anterior area successively almost the same size. Genal punctures subequal in size and density to the discal punctures. Pronotum (Fig. 24 B). Margin between anterior and medial-lateral angle almost straight. Medial angle of pronotum rounded. Margin between medial-lateral angle and posterior-lateral angle almost straight. Disc punctures half size to anterior-lateral ones and separated by more than one diameter of each puncture. Basal punctures smaller than anterior-lateral ones and separated by approximately one diameter of each puncture. Hypomera. With ocellated and setigerous punctures on the anterior part (as Fig. 3 B, white arrow). Most of punctures incompletely closed posteriorly and with setae (as Fig. 3 B, green arrow). Anterior punctures denser and larger than posterior ones. Elytra (Fig. 24 C). Carina of the ninth interstria not reaching middle of elytral length. Elytral apex on interstriae III, V – VII with tubercles. Striae I – VII almost inconspicuous. Width of third stria on disc ~ 1 / 40 of the distance between striae II and III. Strial punctures variable in size, ≥ 2 × wider than the stria. First stria slightly wider and deeper than second stria. Stria VIII conspicuous apically and laterally and reaching carina of the ninth interstria. Punctures on interstriae approximately separated by two diameters. Punctures of the third interstria on disc occupying ~ 1 / 7 of the distance between striae II and III. Interstriae with shiny points mixed with the punctures. Points smaller than interstrial punctures, ~ 4 × smaller. Metaventrite. Anterolateral areas of metaventral process with punctures not completely closed and separated by less than one diameter of each puncture. Anterocentral area of metaventral process with few and small punctures, slightly larger in size than the discal punctures. Punctures on the lateral lobules most of them not completely closed, separated by less than one diameter of each puncture. Legs. Protibia regularly broadens toward the apex. Profemora with punctures separated by less than one diameter of each puncture. Mesofemur with punctures separated by ≥ 2 × the diameter of each puncture. Mesofemur with unarmed on the posterior edge. Metafemur with punctures separated by ≥ 1 × the diameter of each puncture. Metatibial spur insertion not elongated. Metatibial spur clearly distinct from the metatibia. Abdomen (Fig. 24 D). Ventrite I regular, not expanded posteriorly. Pygidium (Fig. 24 E). Pygidial punctures variable in size and density. Punctures separated by one or less than the diameter of each puncture on the disc, more disperse towards the sides. Discal punctures, on the center of the pygidium, small, each puncture occupying ~ 1 / 38 of the distance between the lateral pygidial margins.

Variation.

Medium-sized male: Protibia regularly broadens toward the apex. Mesofemur unarmed on the posterior edge. Metafemur strongly constricted basally and broadens toward the apex. Metatibial spur insertion elongated, with the length subequal to the basal two tarsomeres. Metatibial spur fused with the metatibia. Internal margin of metatibia with a basal irregular carina. Carina reduced in the middle of the metatibial length; following this reduction, the carina rises again as a irregular carina (giving the appearance of having two carinae). Ventrite I expanded posteriorly, expansion reaching the fourth ventrite; on ventrite III, the expansion narrower than the distance between mesocoxae. Apparently, the basal part of the ventrite I, between the metacoxae is elevated (Fig. 25 B – C).

Known distribution

(7 A red cross). This species is only known from the type locality: the Maracaibo Basin, Venezuela. As this locality is highly unspecific, the red cross is intended only as a graphical representation of the possible distribution and, for this reason, is highlighted with a question mark (?).

Remarks.

The lectotype is designated following the Article 74 of the International Code of Zoological Nomenclature (ICZN 1999) and the recommendations herein, in order to stabilize the nomenclature.

This species is known to us only from the type series: a male lectotype (RMNH) and a female paralectotype (NMPC) (although this specimen bears a male symbol in the paralectotype label). The now-designated lectotype was originally housed in the Valck Lucassen collection in Vorden (Holland) (Balthasar 1939). After Mr. F. T. Valck Lucassen’s death in September 1939, his collection was transported to the Leiden Museum (De Jong 1970). The paralectotype was originally housed in Balthasar collection and is now housed in NMPC (Génier 2001). The paralectotype was reviewed in person and the redescription here was made using that specimen. The lectotype was examined by a photographs kindly provided by Dr. Fernando Vaz de Mello (Fig. 4 K) and Dr. Olivier Montreuil (Fig. 25) It is not clearly visible, but apparently the first ventrite is elevated (Fig. 25 B, C).

We consider this species to be closely related to D. nobile sp. nov. based on the size of the striae, the size and density of the interstrial punctures, the number and distribution of the tubercles on the elytral apex, the shape of the internal carina of the metatibia, the apparent elevation of the first ventrite, and the distribution.