Ambrysus Stål

Reynoso-Velasco, Daniel, Sites, Robert W. & Novelo-Gutiérrez, Rodolfo, 2016, The Ambrysus Stål (Heteroptera: Naucoridae: Cryphocricinae) of Mexico: Revision of the subgenus Syncollus La Rivers, Zootaxa 4126 (1) : -

Genus Ambrysus Stål

Ambrysus Stål 1862 : Stett. Ent. Zeit. 23: 459. Type species: Ambrysus signoreti Stål 1862 . Subsequent designation ( Kirkaldy1906).

Discussion. Stål (1862) established the genus Ambrysus for three Mexican species ( A. melanopterus , A. pudicus , and A. signoreti ) and indicated it differed from the genus Naucoris Geoffroy in having a deep depression on the anterior margin of the pronotum, a character later used by Montandon (1897) as the diagnostic feature for the subfamily Cryphocricinae . More recently, La Rivers (1951, 1953) provided detailed descriptions of the genus Ambrysus , which includes five subgenera ( La Rivers 1952, 1965; Nieser et al. 1999). Of these, Acyttarus La Rivers and Picrops La Rivers are monotypic ( A. funebris La Rivers and A. usingeri La Rivers , respectively) ( La Rivers 1965); Melloiella De Carlo includes two species [ A. lamprus Nieser, Pelli , & de Melo and A. truncaticollis (De Carlo) ] ( Nieser et al. 1999); Syncollus La Rivers comprises eight species after removal of A. partridgei , and the remaining 71 species belong to the subgenus Ambrysus Stål.

La Rivers (1952) divided Ambrysus into two subgenera to accommodate A. usingeri with the subgenus Picrops. The features distinguishing this subgenus were the presence of four or more rows of small spines on the distal end of the hind tibia and the males bearing a short lateral process on tergum VI. In his revision of the fauna of Ambrysus from the United States, La Rivers (1951) recognized the divisions Coalescens and Disjunctus within the subgenus Ambrysus , based on the position of the propleura with respect to the prosternum. The former included species with the propleura closely appressed to the adjacent prosternum (prosternellum). In this case the propleura and the anterior part of the prosternum (probasisternum) are positioned at the same level dorsoventrally. The division Disjunctus included species with the propleura detached from the prosternellum; thus, the propleura are at a lower level (further ventrad) than the probasisternum ( Fig. 1 ).

In a later paper, La Rivers (1965) created the subgenus Acyttarus for the species A. funebris , which was the sole species lacking a costal cell in the hind wings. In addition, he elevated the Coalescens division to subgeneric rank as Syncollus (from Greek syn "together" and Latin collus "neck") and the species originally placed in the Disjunctus division were assigned to the subgenus Ambrysus .

Since La Rivers (1951) first used the shape of the male accessory process of tergum VI and the shape of the female mediosternite VII (subgenital plate) in his revision of the fauna of Ambrysus in the United States, these features have been widely used as the two main diagnostic features for distinguishing species of the genus. We have examined all species of Ambrysus from Mexico including most type specimens, and many thousands of museum and freshly collected specimens. The features used by La Rivers are somewhat instructive, although greater intraspecific variation exists in their expression than was previously considered. In addition to these, we discovered that the medial lobes of male tergum VIII (pseudoparameres) and characteristics of the ventral side of the aedeagus also are important diagnostic features at the species and species complex levels (see Sites & Reynoso- Velasco 2015). Each species complex is best characterized by a certain character or combination of these characters, which differs among complexes. For example, in the Ambrysus stali La Rivers complex, the left ventral lobe of the phallosoma is consistent among species, whereas the other three characters are more informative at the species level ( Sites & Reynoso-Velasco 2015).

Ambrysus is distributed in the New World from the northern United States ( La Rivers 1951) south to Argentina ( La Rivers 1971), with the greatest number of species in Mexico where 40 species have been reported. The Yucatan Peninsula has few surficial waters and habitats therein are not consistent with those of species of Ambrysus . As a result, our collections did not yield Ambrysus from those waterbodies and no specimens from this area were found in museum collections. Thus, Ambrysus apparently does not occur in the Yucatan Peninsula.

Figures

FIGURE 1. Prothorax (ventral view) of specimens in the subgenera Syncollus and Ambrysus. (A) Ambrysus (Syncollus) circumcinctus, (B) Ambrysus (Ambrysus) inflatus. pb = probasisternum, pp = propleuron, ps = prosternellum.