Taxonomic Position

Cohort Gamasina

    Subcohort Dermanyssiae

  Superfamily Ascoidea

Family: Ascidae Voigts & Oudemans

Subfamily: Melicharinae

Mucroseius Lindquist

 

Diagnostic characters:

• Fixed chela with a pointed or rounded membranous projection distally

• Leg IV with macrosetae

• All or most R-setae in soft cuticle

• Metasternal plates present, but stp3 absent.

 

Ecology and Distribution.  Associated with cerambycid beetles (Monochamus and Mecynippus) in North America and Eurasia.

 

Similar taxa not in the Lucid key:  Orolaelaps De Leon

Similar taxa. Mucroseius is sometimes considered a junior synonym of Melichares, but species of the latter lack metasternal plates.  The Proctolaelaps hystrix group has R5-7 in soft cuticle and is similar to Mucroseius, but lacks the distal cheliceral process.  Species of Proctogastrolaelaps have a separate ventral shield; species of Rhinoseius, Tropicoseius, and Xanthippe has incised dorsal shields.

 

Key to the genera of Melicharinae

1.   Idiosoma narrow, dorsal shield greater than twice as long as wide; leg setation strongly neotenous, genua I-II-III-IV with 12-7-6-7 setae, tibiae with 11-7-6-6 setae; female lacking metasternal plates and with ventri-anal shield bearing 1-3 pairs of ventral setae in addition to circumanal setae.........Mycolaelaps

-    Idiosoma broader, legs not strongly neotenous, meatsternal plates present or absent, only anal shield or separate anal and ventral shields............................................................................................2

2. Female with separate ventral shield bearing 4 pairs of setae between genital and anal shields; posterior connection of peritrematal shield to exopodal plate beside coxa IV broad (subequal to width of stigma); corniculi slender, acute; rows of deutosternal denticles narrow, in deep trough; epistome convex, smooth; movable chela of female unidentate...........................................................Proctogastrolaelaps

-   Ventral area not sclerotized, only small anal shield with 3 circumanal setae present..........................3

3.  Fixed chela of female and nymphs with pointed or rounded flange-like projection distally; leg IV with 1 or 2 erect macrosetae on telotarsus (pd2, +/- ad2); 3rd pair of sternal pores absent.......Mucroseius

-    Fixed chela without distal flange-like projection; leg IV usually without macrosetae; 3rd pair of sternal pores usually present ..........................................................................................................................4

4.  Dorsal shield of adults with pair of deep midlateral incisions, lacking setae z3 on podonotal region; movable chela with 0 or 1 tooth; female without metasternal plates..........................................................6

-   Dorsal shield of adults entire, usually with setae z3 on podonotal region; movable chela with 3 teeth; with or without metasternal plates............................................................................................................5      

5.  Adults with 7-13 pairs of marginal (r-R) setae on soft lateral cuticle (rarely fewer if some r-R setae lacking); female with 14-15 pairs of setae on opisthonotal region of dorsal shield and lacking metasternal plates (except in Orolaelaps)..................................................................................................Melichares

-   Adults with 1-4 pairs of posterior marginal (R) setae on soft ventro-lateral cuticle, all others on edge of dorsal shield; female with 18-22 pairs of setae on opisthonotal region of dorsal shield; female usually with metasternal plates .................................................................................................. Proctolaelaps

6.  Movable chela unidentate; female with 1st pair of sternal setae on soft cuticle in front of sternal shield; male with separate ventral & anal shields; male leg II with tarsal seta pv1 unmodified.........Xanthippe

-    Movable chela edentate; female with first pair of sternal setae on sternal shield; male usually with consolidated ventrianal shield; male leg II with apical tarsal seta pv-1 slightly to conspicuously thickened....7

7.  Tibiae III and IV with 9 and 10 setae respectively (pl2 present); dorsal shield with setae s6; female with hyaline anterior margin of epigynial shield rounded, and with genital setae on lateral edges of this shield; male tarsus II with seta pv-1 knob- or spine-like, and tarsus III with 1-3 setae (always av2) knob-like; male spermatodactyl directed anteriorly........................................................................... Tropicoseius

-     Tibiae III and IV with 8 and 9 setae respectively (pl2 absent); dorsal shield lacking setae s6; female with hyaline anterior margin of epigynial shield usually truncated or emarginated, and with genital setae on soft cuticle flanking this shield; male tarsus II with seta pv1 but slightly thickened, and tarsus III without modified setae; male spermatodactyl directed posteroventrally................................... Rhinoseius

 

References

Evans EO & Till WM.  1979.  Mesostigmatic mites of Britain and Ireland (Chelicerata: Acari-Parasitiformes).  An introduction to their external morphology and classification.  Transactions of the Zoological Society of London 35 (2): 145-270.

Halliday RB, Walter DE & Lindquist EE.  1998.  Revision of the Australian Ascidae (Acarina: Mesostigmata).  Invertebrate Taxonomy 12: 1-54.

Karg W. 1993. Acari (Acarina), Milben. Parasitiformes (Anactinochaeta). Cohors Gamasina Leach. Raubmilben. (Second Edition). Die Tierwelt Deutschlands 59: 1-523.

Krantz GW. 1986. A Manual of Acarology. Second edition, 1978, emended 1986. (Oregon State University Book Stores, Corvallis, Oregon USA).

Krantz GW & Ainscough B.  1990.  Mesostigmata.  pp. 583-665, in DL Dindal (ed) Soil Biology Guide.  John Wiley & Sons: Brisbane.

Lindquist EE.  1962.  Mucroseius monochami, a new genus and species of mite (Acarina: Blattisocidae [sic]) symbiotic with sawyer beetles.  Canadian Entomologist 94: 972-980.

Lindquist EE & Evans GO. 1965. Taxonomic concepts in the Ascidae, with a modified setal nomenclature for the idiosoma of the Gamasina (Acarina : Mesostigmata). Memoirs of the Entomological Society of Canada 47: 1-64.

Lindquist EE, Wu KW.  1991.  Review of mites of the genus Mucroseius (Acari: Mesostigmata: AScidae) associated with sawyer beetles (Cerambycidae: Monochamus and Mecynippus) and pine wood nematodes [Aphelenchoididae: Bursaphelenchus xylophilus (Steiner and Buhrer) NIckle], with descriptions of six new species from Japan and North America, and notes on their previous misidentifications.  Canadian Entomologist 123: 875-927.