Review and redescription of species in the brasiliana group of Smicridea (Rhyacophylax) (Trichoptera, Hydropsychidae, Smicrideinae): exploration of the utility of geometric morphometrics as a method for delimitation and characterization of species in the genus

Abstract

The Smicrideabrasiliana species group includes five species distributed in northeastern Argentina and Brazil: Smicridea (Rhyacophylax) brasiliana (Ulmer), S. (R.) weidneri Flint, S. (R.) vermiculata Flint, S. (R.) arobasis Flint, and S. (R.) nanda Flint. The original descriptions of these species and their placement in the brasiliana species group were mainly based on the morphology of the male genitalia. However, the fine structure of the internal sclerites of the phallus, which proved to be useful for species delimitation, was not analyzed at the time. In this contribution, we provide a detailed description of the male genitalia and the morphology of the head, and analyze the shape of the wings using geometric morphometrics. The analyzed species can be easily differentiated by the shape of the phallus, especially by the structure of the internal sclerites, the shape of the head in dorsal view, and the shape of the cephalic setose warts. Furthermore, the geometric morphometric approach allowed their separation through the wing shape. The preliminary analysis of these features suggests that the brasiliana species group is not natural but its monophyly should be further tested within the framework of a phylogenetic analysis of all the species of the subgenus Rhyacophylax.

Keywords: Forewing shape; Neotropical; Smicridea (Rhyacophylax) atrobasis; Smicridea (Rhyacophylax) nanda; Smicridea (Rhyacophylax) vermiculata; Smicridea (Rhyacophylax) weidneri; male genitalia.

Figure 1.

Heads in dorsal view of the species of the brasiliana group ASmicridea (Rhyacophylax) brasilianaBS. (R.) weidneriCS. (R.) vermiculataDS. (R.) atrobasisES. (R.) nanda. Abbreviations: CSL length of the coronal suture, IOD interocular distance, MEW maximum eye width, MHW maximum head width. Scale bar: 1 mm.

Figure 2.

Forewing of Smicridea (Rhyacophylax) mesembrina showing the location of the selected landmarks (1–10).

Figure 3.

Male genitalia of Smicridea (Rhyacophylax) brasilianaA segments IX, X, inferior appendages and phallus, lateral view B segments IX, X and inferior appendages, dorsal view C tip of the phallus, lateral view (lateral spines removed) D tip of the phallus, dorsal view E tip of the phallus, ventral view.

Figure 4.

Male genitalia of Smicridea (Rhyacophylax) weidneriA segments IX, X, inferior appendages and phallus, lateral view B segments IX, X and inferior appendages, dorsal view C tip of the phallus, lateral view D tip of the phallus, dorsal view.

Figure 5.

Male genitalia of Smicridea (Rhyacophylax) vermiculataA segments IX, X, inferior appendages and phallus, lateral view B segments IX, X and inferior appendages, dorsal view C tip of the phallus, lateral view D tip of the phallus, dorsal view.

Figure 6.

Male genitalia of Smicridea (Rhyacophylax) atrobasisA segments IX, X, inferior appendages and phallus, lateral view B segments IX, X and inferior appendages, dorsal view C tip of the phallus, lateral view D tip of the phallus, dorsal view (left evaginated, right invaginated).

Figure 7.

Male genitalia of Smicridea (Rhyacophylax) nandaA segments IX, X, inferior appendages and phallus, lateral view B segments IX, X and inferior appendages, dorsal view C tip of the phallus, lateral view D tip of the phallus, dorsal view.

Figure 8.

A Canonical Variate Analysis (CVA) scatter plot of the wing shape landmark data of eight Smicridea species B, C patterns of shape change along each axis by superposition of the mean configurations of the species located in extreme morphospaces of each axis B superposition of the mean (average) wings shape of Smicridea (Rhyacophylax) mesembrina - S. (R.) weidneriC superposition of the mean wings shape of S. (R.) mesembrina - S. (R.) vermiculata.

Figure 9.

Principal Component Analysis (PCA) of the geometric landmark data of the wings of the brasiliana species group A scatter plot showing the average configuration of the wing shape in the deformation grids of each species from consensus shape of species group (indicate in the center of the plot) in the first two CPs. The circles represent the locations of the reference points in the mean shape of each species BUPGMA. Dendrogram from Mahalanobis distance of brasiliana species group and C without Smicridea (Rhyacophylax) atrobasis.

Figure 10.

Violin plot of the centroid sizes (CS) of the wings of the ten Smicridea species analyzed. Bar: no significant differences between CSs (p > 0.05). *: n = 1.