Torrenticola occidentalis (Marshall, 1933)

Fisher, J. Ray, Fisher, Danielle M., Skvarla, Michael J., Nelson, Whitney A. & Dowling, Ashley P. G., 2017, Revision of torrent mites (Parasitengona, Torrenticolidae, Torrenticola) of the United States and Canada: 90 descriptions, molecular phylogenetics, and a key to species, ZooKeys 701, pp. 1-496 : 1

Torrenticola occidentalis (Marshall, 1933)

Atractides occidentalis Marshall, 1933: 40.

Torrenticola occidentalis Mitchell, 1954: 40.

Material examined.

HOLOTYPE (♀): from USA, Wyoming, Medicine Bow National Forest, 1928, by JW Scott, RM280072.

Type deposition.

Holotype (♀) deposited in the CNC.

Diagnosis.

Torrenticola occidentalis are similar to other members of the Ellipsoidalis Group ( T. ellipsoidalis , T. multiforma , and T. leviathan ), and in being among the largest Torrenticola in the west (dorsum length ♀ = 700-885; ♂ = 665-850), although T. sierrensis are also large (dorsum length ♀ = 700-880; ♂ = 590-735) but can easily be distinguished from the Ellipsoidalis Group by being circular instead of ellipsoid or rectangular (dorsum length/width = 1.17-1.28 in T. sierrensis , 1.30-1.67 in Ellipsoidalis Group). T. occidentalis can be differentiated from T. ellipsoidalis by having a shorter medial suture (20 in T. occidentalis , 40-57.5 in T. ellipsoidalis ) and by having more elongate anterio-lateral platelets (length/width = 2.54 in T. occidentalis , 2.00-2.39 in T. ellipsoidalis ). T. occidentalis can be differentiated from T. multiforma by having stockier subcapitular rostra (length/width = 2.15 in T. occidentalis , 2.5-2.8 in T. multiforma ). T. occidentalis can be differentiated from T. leviathan by having less elongate pedipalpal tibiae (length/width = 3.33 in T. occidentalis , 3.43-4.20 in T. leviathan ) and a shorter dorsum (length ♀ = 770 in T. occidentalis , 845-870 in T. leviathan ).

Re-description.

Female (Figure 171) (n = 1) (holotype only) with characters of the genus with following specifications.

Dorsum- (770 long; 590 wide) ellipsoid with pink coloration without a distinct pattern. Anterio-medial platelets (145 long; 76.25 wide). Anterio-lateral platelets (235 long; 92.5 wide) free from dorsal plate. Dgl-4 much closer to the edge of the dorsum than to the muscle scars (distance between Dgl-4 455). Dorsal plate proportions: dorsum length/width 1.31; dorsal width/distance between Dgl-4 1.30; anterio-medial platelet length/width 1.90; anterio-lateral platelet length/width 2.54; anterio-lateral/anterio-medial length 1.62.

Gnathosoma - Subcapitulum (370 long (ventral); 282.5 long (dorsal); 170 tall) colorless. Rostrum (145 long; 67.5 wide) short. Chelicerae (370 long) with curved fangs (75 long). Subcapitular proportions: ventral length/height 2.18; rostrum length/width 2.15. Pedipalps with tuberculate ventral extensions on femora and genua. Palpomeres: trochanter (50 long); femur (127.5 long); genu (87.5 long); tibia (100 long; 30 wide); tarsus (15 long). Palpomere proportions: femur/genu 1.46; tibia/femur 0.78; tibia length/width 3.33.

Venter - (980 long; 660 wide) colorless. Gnathosomal bay (202.5 long; 97.5 wide). Cxgl-4 subapical. Medial suture (20 long). Genital plates (235 long; 210 wide). Additional measurements: Cx-1 (385 long (total); 180 long (medial)); Cx-3 (430 wide); anterior venter (217.5 long). Ventral proportions: gnathosomal bay length/width 2.08; anterior venter/genital field length 0.93; anterior venter length/genital field width 1.04; anterior venter/medial suture 10.88.

Male unknown.

Immatures unknown.

Etymology.

Marshall (1933) did not specify an etymology for the specific epithet ( occidentalis ). However, surely this name refers to the type locality of this species in western United States (occidens, L. direction of the setting sun, west).

Distribution.

Known only from South-central Wyoming (Medicine Bow National Forest) (Figure 170), from a single female collected from trout stomach contents.

Remarks.

Unfortunately, we were unable to acquire fresh material of Torrenticola occidentalis and therefore this species is not included in our phylogenetic analyses. However, we were able to examine the holotype. Based upon overall similarity and a short, conical rostrum, we place this species in the Miniforma Complex and the Ellipsoidalis Identification Group