Metarhombognathus Newell, 1947,

Bartsch, Ilse, 2015, The genital area of Halacaridae (Acari), life stages and development of morphological characters and implication on the classification, Zootaxa 3919 (2), pp. 201-259: 223-224

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http://dx.doi.org/10.11646/zootaxa.3919.2.1

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http://treatment.plazi.org/id/03C887E5-FFFD-FF85-FF12-A1F6FDB7FD2E

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scientific name

Metarhombognathus Newell, 1947
status

 

Metarhombognathus Newell, 1947 

( Fig. 64View FIGURE 64)

Type species. Rhombognathus armatus Lohmann, 1893  .

Adults. In female GP reduced in size, separated from AP. GP only slightly larger than GO, anterior pair of pgs on or in margin of GP, two following pairs in striated integument. Genital sclerites lack sgs. Anterior-most of three pairs of internal gac more slender than following pairs and adjacent or fused to second pair ( Bartsch 1975 a: fig.

14 a, 2003 c: fig. 6 M); that anterior pair may be obscured in ventral aspect. Pairs of gac at and posterior to the level of middle of GO, posterior pair internally extending posteriad beyond GO. Ovipositor short, both at rest and everted. Genital spines with numerous delicate spicules included in a membrane. Everted ovipositor with four pairs of genital spines. Two antero-apical pairs and one of postero-apical pair recognizable when ovipositor at rest ( Bartsch 1975 a: fig. 14 a). In male GP and AP fused. Length of male GO similar to that of female. GA with 30–40 pairs of bristle-like, smooth pgs, genital sclerites with three pairs of small, rather spiniform sgs. Acetabula internal, situated adjacent in posterior part of GO ( Fig. 64View FIGURE 64); gac somewhat smaller than in female. As in female, anterior pair of acetabula more narrow and fused with second pair ( Bartsch 1972: fig. 10, 2003 c: fig. 6 I). Adults without epimeral pores.

Juveniles. With one larva and two nymphs. Genital and anal plate fused in both deutonymph and protonymph. Deutonymph with two pairs of internal gac, two pairs of pgs, no sgs ( Bartsch 2003 c: fig. 6 G). Protonymph with single pair of gac; pgs and sgs not developed ( Bartsch 2003 c: fig. 6 F). Larva with pair of tube-like epimeral pores ( Bartsch 1974 b: fig. 1 c).

Remarks. Two species have been described, both are common in tidal green algal belts of the northern Atlantic and Arctic Sea ( Bartsch 2009 a).