Eriomacrotergum Rodrigues, Navia, Oliveira & Ferragut, 2016, n. gen.

Eriomacrotergum n. gen. Rodrigues, Navia & Oliveira

(Figs.1–6)

Type species: Eriomacrotergum flechtmanni n. sp.

Diagnosis. Reduced prodorsal shield with short narrow-based frontal lobe, not emarginated; scapular setae (sc) laterally displaced, on posterolateral shield margin; sc tubercles with perpendicular bases in relation to dorsal annuli, directing setae dorsally upwards or laterally. Dorsal opisthosoma with first annuli narrow followed by broad annuli; first broad annulus forming an opisthosomal plate, elevated in relation to prodorsal shield and gnathosoma, without lateral projections. Opisthosoma abruptly downcurved at level of setae f. Margins of broad dorsal annuli enlarged, laterally rounded. All coxal, lateral and ventral setae present. Paraxial tibial setae (l’) absent on both legs. Anterior genital apodeme T-shaped, with shortened longitudinal bridge; long axis of spermathecae directed laterad.

Remarks. According to the classification of Amrine et al. (2003) Eriomacrotergum is placed in the Tegonotini because of: its entire empodium; presence of scapular setae and tubercles; and opisthosoma presenting lateral lobes and plate.

Eriomacrotergum n. gen. is similar to the tegonotine genera Scolocenus Keifer, 1962; Dicrothrix Keifer, 1966; Phyllocoptacus Mohanasundaram, 1984; Hemiscolocenus Mohanasundaram, 1986; Tumoris Huang, 2001; Glabrisceles Navia & Flechtmann, 2002; and Asetidicrothrix Wei, Wang & Qin, 2009 in the presence of an opisthosomal plate. However it differs from all these genera in: the reduced prodorsal shield and frontal lobe (in these genera the prodorsal shield is not reduced and the frontal lobe is broad-based, covering at least the palpcoxal base); the presence of a narrow first dorsal annulus anterior to the opisthosomal plate (in these genera the opisthosomal plate is situated just posterior to the prodorsal shield); and in the sc seta near the rear shield margin (placed ahead of rear shield margin in other genera). The new genus is also similar to Paniculatus Boczek and Chandrapatya, 2000 in the sc setae laterally displaced on the rear shield margin. However it can be distinguished from this genus by the reduced prodorsal shield (not reduced in Paniculatus) and the opisthosomal plate (lacking in Paniculatus).

The new genus also presents some traits similar to genera not belonging to the Tegonotini. It is similar to Ashieldophyes Mohanasundaram, 1984 (Ashieldophyinae) in the reduced prodorsal shield; however the new genus can be distinguished from this by the well developed sc setae tubercles and the ventral setae d and e (lacking in Ashieldophyes). It is similar to Tumescoptes Keifer, 1939 (Phyllocoptinae: Acaricalini) in the dorsal opisthosoma with narrow annuli anterior to the opisthosomal plate; however, in addition to the divided empodium (which characterize the Acaricalini), it differs from the new genus in the: prodorsal shield size (well developed in Tumescoptes, reduced in the new genus); and position of the sc setae and tubercles (centrad, anterior to rear shield margin in Tumescoptes; laterally displaced, on the rear shield margin in the new genus). It is similar to Neooxycenus Abou-Awad, 1981 (Phyllocoptinae: Anthocoptini) in the sc setae laterally displaced on the rear shield margin, but differs from this by the reduced prodorsal shield (not reduced in Neooxycenus) and opisthosomal plate (lacking in Neooxycenus).

The female internal genitalia structures in Eriomacrotergum n. gen. are not similar to those described from other Tegonotini genera (see Amrine et al. 2003). Instead, its shape resembles those of the Cecidophyinae; the anterior genital apodeme of the new genus looks like a T-shaped structure and it is most likely a plate situated in a vertical plane, with a shortened longitudinal bridge; and the long axis of the spermathecae are directed laterad; while in most of the tegonotine genera the genital apodeme is trapezoidal, as e.g. in Acalox Keifer, 1975; Dicrothrix Keifer, 1966; Oxycenus Keifer, 1961; or Tegonotus, Nalepa, 1890. However, the new genus differs from cecidophyine genera in the most important trait of this subfamily: the gonopore and external associated genitalic structures. In the new genus, the female genitalia are not appressed to the coxae (which are not distinctly separated) and do not project remarkably from the venter as in the cecidophyine.

Etymology. The generic name is composed of Erio, prefix of Eriophyidae, the family to which the new taxon belongs; plus the Ancient Greek term macro for “large” and the Latin term tergum for “back”, regarding the first broad dorsal annulus expanded, forming an opisthosomal plate. The gender is neuter.