Parygrus angustatus Grouvelle, 1896

Barr, Cheryl B. & Shepard, William D., 2020, Hiding in plain sight: rediscovery and review of Parygrus Erichson, 1847, with description of five new species from the Neotropics (Coleoptera: Byrrhoidea Dryopidae), Zootaxa 4755 (1), pp. 99-128 : 107-108

Parygrus angustatus Grouvelle, 1896

(Figs 2, 8, 9)

Holotype specimen. BRAZIL: “Bresil / R. de Jan [blue-green, handwritten] // Museum Paris / 1917 / Coll. Grouvelle [white, printed] // TYPE [red, printed] // Dryops /angustatus / ty. Grouv [off-white, handwritten]”. In his description, Grouvelle stated “ Rio de Janeiro. Collection Grouvelle” ( Grouvelle 1896a, p. 215). Depository, MNHN. The type specimen itself was not examined, only the photographic image and label data from the photo.

Additional specimens, photographic images (2). BRAZIL: “Bresil / Theresop [handwritten] // MUSEUM PARIS [light blue, printed] / Coll. A. Grouvelle 1915 // Parygrus / angustatus / gr. [handwritten]”; “Neu-Freiburg, / Süd-Brasilien. / F. Wiengreen leg. / ded. 9.11. 1897. // Parygrus angustatus / Grouv.”. Depository, MNHN. Only photographic images and label data from the photos were examined .

Additional specimens examined (7). BRAZIL: “ Type [circular label with red border, printed] // 20295 [handwritten] // Fry / Rio Jan°. [handwritten] // Fry Coll. / 1905-100.” [printed] // “ Parygrus angustatus / ty. Grouv [handwritten]” (1; head missing); “Fry / Rio Jan°. [handwritten] // Fry Coll. / 1905-100. [printed]” (2); “Fry / Rio Jan°. [handwritten] // Fry Coll. / 1905-100. [printed] // Parygrus / angustatus [handwritten]” (1; right elytron missing); “9354 // Fry / Rio Jan°. [handwritten] // Fry Coll. / 1905-100. [printed] // Parygrus / angustatus / var. [?-illegible word] Grouv [handwritten]” (1); “Rio [pink oval label, handwritten] // Pascoe / Coll. / 93–60.” [printed] (1) . ARGENTINA: “Argentine Republic: / Villa Ana, F. C. S. Fe. / December 1924. / K. J. Hayward. // Brit. Mus. / 1925-217” [printed] (1). Depository, NHMUK. These specimens may not be conspecific with the type nor with each other; see Discussion below .

Provisional diagnosis. The type specimen of P. angustatus ( Fig. 8 ) is much longer (7–8 mm) than specimens of any of the other species except for P. parallelus ( Fig. 11 ). Keeping in mind that the images of P. parallelus are not of the type, P. angustatus appears to differ from that species by the following: elytra parallel-sided (vs. sinuate laterally, not parallel-sided); pronotum widest in about a third of the distance from the base (vs. widest at base), lateral margins not raised nor widely explanate (vs. raised, widely explanate), with a weak longitudinal carina (not visible in Fig. 8 ) (vs. without a carina); elytral striae not distinct, punctures small (vs. striae distinct, punctures larger), effaced at posterior third (vs. not effaced).

General description. Since we were unable to examine the holotype, only a limited description is possible based on the original descriptions ( Grouvelle 1896a) and images of the type ( Fig. 8 ). From a translation of the original Latin and French descriptions: 7–8 mm long, elongate-oval; convex; pronotum widest at basal third, with a weak longitudinal carina (subcarinate), anterior margin not rimmed in the middle, lateral borders arcuate; scutellum curvilinear triangular; elytra a little wider than pronotum at base, punctate-striate, striae effaced at posterior third. Additional observations from the image of the type: body is parallel-sided and tapered posteriorly; pronotal posterolateral angles are depressed, if not explanate; median longitudinal pronotal carina is not discernable in the Fig. 8 ; elytra punctate but not obviously striate, punctures small and shallow; protibiae deflexed and enlarged at apical third, indicating that the type is likely a male.

Distribution. Brazil (described from Rio de Janeiro), and possibly Argentina (Fig. 2).

Etymology. Grouvelle did not cite an etymology. However, the specific epithet angustatus is composed of angustus (L.), meaning “narrow,” and –atus (L.), meaning “having the nature of.”

Comments. Parygrus angustatus was described by Grouvelle (1896a) in both Latin and French, the French description being the more detailed. There are two specimens labeled as the type of P. angustatus , one in the MNHN ( Fig. 8 ) and the other in the NHMUK ( Fig. 9 ). The true type, with data closest in agreement with that in Grouvelle’s description, is the MNHN specimen. Nonetheless, it is puzzling that it bears the determination label “ Dryops angustatus ” ( Fig. 8 ) because Grouvelle described the species in Parygrus .

It is interesting that the determination label of the NHMUK specimen ( Fig. 9 ), also from Rio de Janeiero, Brazil and labeled as the type of P. angustatus , is written in the same hand as the determination label of Grouvelle’s P. elateroides holotype ( Fig. 10 ). Yet the circular format of the type label of the NHMUK specimen, from the Fry Collection, is identical to the type label of P. erichsoni described by Waterhouse 20 years earlier. These are of a different format than the type labels from the MNHN Grouvelle collection, which are rectangular.

The determination labels on two other images sent from the MNHN (Additional specimens, photographic images) do not match the handwriting of the label on the type, but one of them bears a Grouvelle Collection label. We suspect that they may not be P. angustatus for the following reasons: In comparison with the image of the type, they both have pronota with widely explanate lateral margins that are widest near the base. The image of the type does not appear to have these pronotal characters, but the angle at which it was taken may have influenced this. Nonetheless, explanate pronotal margins are not mentioned in the description, and the pronotum was stated to be widest at the first third from the base. In addition, the type has the elytra parallel-sided, whereas the others are sinuate with the margin explanate at the basal third. They more closely resemble the non-type images of P. parallelus than that of the type of P. angustatus .

Among the seven specimens examined from the NHMUK (Additional specimens examined), five were labeled as being from the Fry Collection, including the erroneously-labeled “type.” The “type” and another of these specimens have similarly handwritten determination labels, which are not in the same hand as the actual type. There is a good deal of morphological variation among the additional specimens (i.e., pronota with or without a longitudinal carina and/or explanate lateral margins) so they are likely not all P. angustatus or all conspecific. However, the false type, a female ( Fig. 9 ), does resemble the image of the holotype, likely a male ( Fig. 8 ).

Figures

FIGURES 8–11. Parygrus species: 8) Parygrus angustatus, holotype: dorsal habitus; specimen labels; 9) Parygrus angustatus, false holotype: dorsal habitus; specimen labels; 10) Parygrus elateroides, holotype: dorsal habitus; specimen labels; 11) Parygrus parallelus, non-type: dorsal habitus; specimen labels (images 8, 10, 11 provided by the MNHN collection-Paris).