Eharius Tuttle & Muma

Kolodochka, L. A., 2023, The Predatory Mites (Phytoseiidae, Parasitiformes) In The Fauna Of Ukraine: Genera Paragigagnatus, Carinoseius, Kampimodromus, Eharius, Typhlodromips, And Euseius, Zoodiversity 57 (6), pp. 477-506 : 490-492

Genus Eharius Tuttle & Muma

Eharius Tuttle & Muma, 1973: 14 .

Type species: Amblyseius chergui Athias-Henriot, 1960 .

Zavicus Arutunjan, 1973: 115 .

Type species: Amblyseius marzhaniani Arutunjan, 1969: 42 .

Kampimodromus : Kolodochka, 1979 a: 8.

Eharius : Kolodochka, 1995 a: 81, 2006: 95; Chant & McMurtry, 2007: 39; Papadoulis et al., 2009: 37.

Genus profile. Dorsal shield of female with 16 pairs of setae and up to 4 pairs of solenostomes (iv, id, il, ic) and with AD1, AD2, AD3, AD4; PD2, PD4; AM1, AM2; AL1, AL3, AL4; PL1, PL3; PM1, PM3, PM4 — on the dorsal shield; AS, PS (both on interscutal membrane). Dorsal shield weakly or considerably sclerotised. The sculpture of the dorsal shield is represented by longitudinally parallel striation with anastomoses (sometimes convex, which creates a distinct folding) in combination with smooth, reticulate or scaly areas in the posterior half of the shield. Dorsal setae fine, sometimes hairy, smooth (PM3 thicker than others, often serrate). Peritremes short, not reaching the level of setae AL1, often much shorter. Ventral part of opisthosoma with 6–7 pairs of setae (MV1 absent) and one unpaired (postanal) seta: PrA1, PrA2, V2, PaA, PsA (unpaired) on ventrianal shield. There are only 3 (V1, MV2, PV) or 2 (V1, PV) pairs of setae on the membrane around the ventrianal shield. One or both setae PrA1 and V2 may be located outside the ventrianal shield as a result of reduction of its anterior part. Anal pores are present. The legs are short, their segments are thickened and wide. There are no macrochaetes on the legs, but the distal parts of the tarsi may have thickened setae. The constituent parts of the gnathosoma are either of normal proportions for the family, or the gnathobase and chelicerae are elongated, while the pedipalps remain relatively short.

Some species of the genus Eharius have a special organ, the gnathobrachium, which is very rare in this family. A similar structure is developed in mites of the genus Paragigagnathus (see above note to the species description of P. insuetus ) and the monotypic genus Gigagnathus Chant, 1965 with type species G. extendus Chant, 1965: 168 (Metaseiulini, Typhlodrominae ) known only from Bermuda ( Chant & McMurtry, 2007). Simultaneously with the presence of the gnatobrachium, the segments of the chelicerae are elongated. Gnathobrachium is present in five of known species Eharius , but absent only in E. kuznetzovi . Interestingly, the pedipalps did not undergo elongation and remained relatively short. Probably, the explanation for this phenomenon should be sought in the feeding behavior of mites, as in the case of the previously considered genus Paragigagnathus .

D i a g n o s i s. The characteristic linear sculpture of the dorsal shield is a common character of the mites of this genus. The genus Eharius is clearly subdivided into two subgenera based on the structure and proportions of the gnathosoma, as shown by Kolodochka (1979). Chant & McMurtry, 2003 proposed to consider them as two species groups based on the presence/absence of seta MV2: the kuznetzovi species group with MV2 and the kostini species group without MV2.

Two species of the two subgenera are known in Ukraine (Kolodochka, 1995).

Notes. 1. Findings of mites of this genus are more often associated with members of the family Lamiaceae . Athias-Henriot (1960) suggested hossible phytophagy of the species E. chergui without specifying the food specialisation (sap? pollen? — L. K.). Judging from the frequent abundance of mites of this species on the plant they inhabit in the absence of herbivorous mites on the plant, such an assumption may have a very real basis.

2. The vast majority of phytoseiids have a gnathosome fixedly attached to the body. The presence of gnathobrachium, which is rare in the family, gives mobility to the gnathosome. It is capable of facultative elongation due to straightening of walls in case, for example, if the total length of chelicerae and gnathobase is insufficient for capturing food. This morphological feature serves as an easily reconised character for grouping forms on the basis of external similarity. However, this trait is under targeted functional pressure to improve food grasping and is therefore subject of homoplasy (convergent or parallel) and thus has a low phylogenetic signal. In this case, the traits free from the influence of functional load are needed. Chetological analysis is the most suitable as a source of such traits, which allows us to use setal topography as an external manifestation of genome features.

In the considered case, species of genus Eharius show a peculiarity not frequently met in other taxa of phytoseiids, namely, absence of some pairs of opisthoventral seta MV. Two species of subgenus Eharius (Zavicus) lack pair MV1, five species of subgenus Eharius (Eharius) lack two pairs of opisthoventral setae (MV1 and MV2).

Since the mites of the family Phytoseiidae are characterized by hypotrichia ( Chant, 1993), the degree of evolutionary advancement of the nominative subgenus in relation to the subgenus Eharius (Zavicus) is obvious, as well as a distinct hiatus in the opisthoventral chaetome between these taxa, demonstrating genetic differences and supported by differences in the structure of the gnathosome, which bear the imprint of functionality (presence or absence of gnathobrachium). On this basis, I consider it expedient to keep two subgenera, nominative and Eharius (Zavicus) , within the genus Eharius Tuttle & Muma.

Subgenus Eharius Tuttle & Muma

Eharius (s. str.): Kolodochka 1995 a: 82.

Type species: Amblyseius chergui Athias-Henriot 1960 .