Mixturopoda, Baker, Anne S. & Monson, Frank D., 2007

Baker, Anne S. & Monson, Frank D., 2007, Mixturopoda Baker and Monson, a new genus of the uropodine family Metagynuridae (Acari: Mesostigmata) from the British Isles, Zootaxa 1665, pp. 1-17: 2-4

publication ID

http://doi.org/ 10.5281/zenodo.180061

publication LSID

lsid:zoobank.org:pub:A5826912-155A-457E-B362-BF50EAA0DAAA

persistent identifier

http://treatment.plazi.org/id/038887EF-0C21-907E-B3FF-FBB8FE46F9F6

treatment provided by

Plazi

scientific name

Mixturopoda
status

gen. nov.

Mixturopoda  gen. nov. ( Figs. 1–27View FIGURES 1 – 2)

Diagnosis

The deutonymph and adults can be distinguished from those of Metagynella  , the only other metagynurid genus, by the absence of pedofossae and the presence of a large, rounded triangular –pentagonal tritosternal base (versus small and approximately rounded rectangular). Also, the genital shield of the adult female of Mixturopoda  bears setae st 5 (versus devoid of setae) and is not incorporated into the ventral plate, while internal genitalic structures between coxae IV are absent in both sexes.

Description

Adult idiosoma approximately parallel-sided, with foveate integument; undivided dorsal shield covers dorsum, bears c. 46 pairs setae; posteroventral marginal shield present, not subdivided into platelets; tritosternum uniramous, base rounded triangular –pentagonal, wider than long; jugular plates absent; margins of hypognathal groove not fused; peritremes straight, not convoluted; exo- and endopodal shields not fused between coxae I and II; palp setal complement (trochanter –tarsus) 2-5 - 4-10 - 13, missing seta on genu hypothesized to be d 3, apotele bifid; chelicera with dorsal seta and distal bulbous sensilla-like structure on fixed digit, pilus dentilis, lateral lyrifissure and sclerotized node absent; gnathotectum with roughly triangular base and long slender central prong; scabellum and pedofossae absent; coxae I approximately cylindrical, located in gnathopodal cavity, not covering base of tritosternum (in uncleared specimens, almost abutting base); femur I with 1 anterolateral and 4 dorsal setae, II with 9 setae, III and IV with 6; genu II with 8 setae; tibiae I – IV with 7 setae, comprising 3 dorsals, 2 laterals and 2 ventrals; tarsus I without ambulacrum, terminating in enlarged hollow receptors; tarsi II –IV with dorsal lyrifissure near peripodomeric fissure, 17 setae present, posterolateral seta pd 3 absent from basitarsi, dorsal setae ad 1 and pd 1 fine and noticeably longer than other tarsal setae. Female genital shield located posterior to coxae IV, not incorporated into ventral shield, bearing genital setae st 5, paragynial shields absent; internal genitalic structures between coxae IV not visible; anus located on ventrianal shield. Male genital aperture circular, located between coxae IV; femur II with greatly enlarged anteroventral seta, tarsus II curved, terminating in large claw-like structure interpreted as seta av 1, posteroventral seta pv 1 of tarsi III –IV enlarged. Deutonymph with 30 pairs setae on undivided dorsal shield, outer setal row borne on separate platelets (some may be contiguous); marginal shield represented by platelets, each bearing 1 seta; opisthogastric region with small shield just posterior to coxae IV and larger ventrianal shield.

Phoretic deutonymph, protonymph and larva Unknown.

Type species

Mixturopoda evansi  sp. nov., by monotypy.

Remarks

The family Metagynuridae  was proposed by Balogh (1943) for his monotypic genus Metagynura  . Unaware of Balogh’s publication, Camin (1953) erected the new family Metagynellidae  to accommodate the genus Metagynella  . Subsequently, Metagynura  and Metagynellidae  were found to be junior synonyms of Metagynella  and Metagynuridae  respectively ( Ryke 1958). Until now, the only additions to the family have been new species of Metagynella  .

Metagynurids are diagnosed by the position of the female genital shield posterior to coxae IV; in other uropodines it is between coxae II –IV. The new taxon is assigned to the family on the basis of possessing this unique character state. Comparison of M. evansi  with specimens and/or morphological accounts of the 15 nominate species of Metagynella  shows that it shares with them other morphological features originally attributed to the family, namely: ambulacra absent from tarsi I ( Balogh 1943; Camin 1953); markedly long sternal shield ( Balogh 1943), and small male genital aperture located between coxae IV, non-contiguous coxae I inserted in the gnathopodal cavity, dorsal shield covering the idiodorsum, marginal shield comprising a narrow posteroventral border, dorsal marginal shields absent and cheliceral shaft very long ( Camin 1953). Also, M. evansi  and Metagynella  species have subcylindrical coxae I that do not cover the tritosternal base. The familial characteristic of presence of pedofossae ( Balogh 1943; Camin 1953) is lacking in Mixturopoda  , as are oval internal genitalic structures between coxae IV ( Balogh 1943) and an oval-shaped idiosoma with smooth integument ( Camin 1953). Furthermore, the form of the tritosternal base, which is regarded as constant within uropodine genera ( Hirschmann & Zirngiebl-Nicol 1969), clearly differs between the new taxon and species of Metagynella  (large and rounded triangular –pentagonal versus small and approximately rounded rectangular). All species of Metagynella  for which the female is known have the genital shield devoid of setae and enclosed by the ventral shield. Neither the free female genital shield nor the location of setae st 5 on this shield seen in M. evansi  has previously been recorded in the Uropodina  . These unique character states, together with the lack of pedofossae and the form of the tritosternal base, clearly distinguish the new taxon from Metagynella  and, therefore, the establishment of a new genus is warranted.

The placing of Mixturopoda  in the Metagynuridae  necessitates the following amendments to the familial diagnosis: female genital shield posterior to coxae IV, free or enclosed in the ventral shield, with or without setae st 5; coxae I subcylindrical, not covering the tritosternal base; idiosoma oval or parallel-sided, with smooth or foveate integument; oval internal genitalic structures between coxae IV present or absent; pedofossae present or absent; tritosternal base small and approximately rounded rectangular or large and rounded triangular –pentagonal. The diagnosis of Metagynella  should also be qualified as follows: female genital shield enclosed in the ventral shield, without setae; idiosoma oval, with smooth integument; oval internal genitalic structures between coxae IV present or absent; pedofossae present; tritosternal base small, approximately rounded rectangular.