Torrenticola dimorpha Fisher & Dowling

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 dimorpha Fisher & Dowling sp. n.

Material examined.

HOLOTYPE (♀): from USA, Texas, Bandera County, Lost Maples State Natural Area, north of Vanderpool; picnic area, (29°48'48"N, 99°34'34"W), 10 October 2010, by IM Smith, IMS100184.

PARATYPES (8 ♀; 5 ♂): Texas, USA: 1 ♂ (ALLOTYPE) from Bandera County, Lost Maples State Natural Area, north of Vanderpool; picnic area, (29°48'48"N, 99°34'34"W), 10 October 2010, by IM Smith, IMS100184 • 1 ♀ and 1 ♂ from Bandera County, Lost Maples State Natural Area, north of Vanderpool; picnic area, (29°48'48"N, 99°34'34"W), 10 October 2010, by IM Smith, IMS100184 • 2 ♀ and 3 ♂ from Bandera County, Lost Maples State Natural Area north of Vanderpool; picnic area, (29°48'48"N, 99°34'34"W), 7 October 2010, by IM Smith, IMS100178 • 2 ♀ from Bandera County, Lost Maples State Natural Area; picnic area, (29°48'48"N, 99°34'34"W), 27 May 1997, by IM Smith, IMS970008 • 1 ♀ from Bandera County, Vanderpool; beside Rt. 187, 0.7 km south of entrance to Lost Maples State Natural Area, (29°48'48"N, 99°34'34"W), 2 May 2009, by IM Smith, IMS090007 • 1 ♀ from Kinney County, Brackettville; beside Rt. 90, 12.1 km west of Rt. 131, (29°20'20"N, 100°32'32"W), 4 May 2003, by IM Smith, IMS030007 • 1 ♀ from Uvalde County, Garner State Park; river crossing site, (29°35'35"N, 99°44'44"W), 28 May 1998, by IM Smith, IMS980027A.

Type deposition.

Holotype (♀), allotype (♂), and some paratypes (5 ♀; 2 ♂) deposited in the CNC; other paratypes (3 ♀; 2 ♂) deposited in the ACUA.

Diagnosis.

Torrenticola dimorpha are similar to other members of the Tricolor Complex ( T. bittikoferae , T. cardia , T. hoosieri , T. kringi , T. larvata , T. mohawk , T. pearsoni , T. olliei , T. sierrensis , T. tricolor , T. trimaculata , and T. unimaculata ) in having a short, conical rostrum. T. dimorpha can be differentiated from all other Torrenticola by having a dorsal plate with a medial extension covering nearly half the length of the anterio-medial platelets and by males having large, highly modified pedipalps, which are expanded vertically and laterally. Additionally, T. dimorpha can be differentiated from most other Tricolor Complex (except T. bittikoferae , T. hoosieri , and T. pearsoni ) by being colorless, whereas most other members have bold patterning.

Description.

Female (Figure 57) (n = 5) (holotype measurements in parentheses when available) with characters of the genus with following specifications.

Dorsum - (590-670 (650) long; 455-520 (490) wide) colorless and ovoid. Anterior dorsal plate with medial extension covering nearly half the length of the anterio-medial platelets. Anterio-medial platelets (117.5-135 (135) long; 52.5-57.5 (57.5) wide). Anterio-lateral platelets (145-172.5 (172.5)) long; 55-65 (62.5) wide) free from dorsal plate. Dgl-4 approximately halfway in between the edge of the dorsum and the muscle scars (distance between Dgl-4 320-360 (360)). Dorsal plate proportions: dorsum length/width 1.29-1.33 (1.33); dorsal width/distance between Dgl-4 1.36-1.48 (1.36); anterio-medial platelet length/width 2.24-2.35 (2.35); anterio-lateral platelet length/width 2.46-2.78 (2.76); anterio-lateral/anterio-medial length 1.19-1.33 (1.28).

Gnathosoma - Subcapitulum (230-260 (255) long (ventral); 150-170 (170) long (dorsal); 110-132.5 (132.5) tall) colorless. Posterior dorsal apodeme long. Rostrum (65-70 (70) long; 42.5-50 (45) wide) very short. Chelicerae (210-245 (235) long) with curved fangs (60-70 (70) long). Subcapitular proportions: ventral length/height 1.90-2.09 (1.92); rostrum length/width 1.40-1.56 (1.56). Pedipalps with long, tuberculate ventral extensions on femora and no ventral extensions on genua. Palpomeres: trochanter (37.5-40 (37.5) long); femur (76.25-85 (82.5) long); genu (52.5-62.5 (60) long); tibia (65-72.5 (70) long; 22.5-22.5 (22.5) wide); tarsus (20-22.5 (22.5) long). Palpomere proportions: femur/genu 1.36-1.48 (1.38); tibia/femur 0.84-0.87 (0.85); tibia length/width 2.89-3.22 (3.11).

Venter - (720-800 (770) long; 505-600 (580) wide) colorless. Gnathosomal bay (120-145 (145) long; 72.5-85 (85) wide). Cxgl-4 apical. Medial suture (25-30 (30)). Genital plates (170-195 (185) long; 162.5-180 (180) wide). Additional measurements: Cx-1 (240-270 (270) long (total); 110-130 (125) long (medial)); Cx-3 (315-350 (350) wide); anterior venter (137.5-155 (155) long). Ventral proportions: gnathosomal bay length/width 1.60-1.79 (1.71); anterior venter/genital field length 0.78-0.84 (0.84); anterior venter length/genital field width 0.85-0.86 (0.86).

Male (Figure 58) (n = 5) (allotypic measurements in parentheses when available) with characters of the genus with following specifications.

Dorsum - (465-510 (500) long; 310-330 (320) wide) colorless and ovoid. Anterior dorsal plate with medial extension covering nearly half the length of the anterio-medial platelets. Muscle scars absent or very faint. Anterio-medial platelets (102.5-115 (107.5) long; 42.5-45 (45) wide). Anterio-lateral platelets (177.5-197.5 (195) long; 42.5-55 (55) wide) free from dorsal plate. Dgl-4 much closer to the edge of the dorsum than to the muscle scars (distance between Dgl-4 225-245 (245)). Dorsal plate proportions: dorsum length/width 1.50-1.58 (1.56); dorsal width/distance between Dgl-4 1.31-1.41 (1.31); anterio-medial platelet length/width 2.34-2.63 (2.39); anterio-lateral platelet length/width 3.38-4.65 (3.55); anterio-lateral/anterio-medial length 1.64-1.81 (1.81).

Gnathosoma - Subcapitulum (227.5-255 (240) long (ventral); 160-177.5 (165) long (dorsal); 100-110 (100) tall) colorless. Rostrum (45-50 (47.5) long; 32.5-37.5 (32.5) wide) very short. Chelicerae (195-235 (205) long) with curved fangs (55-65 (60) long). Subcapitular proportions: ventral length/height 2.17-2.40 (2.40); rostrum length/width 1.29-1.46 (1.46). Pedipalps highly modified and expanded, with long, tuberculate ventral extensions on femora and no ventral extensions on genua. Palpomeres: trochanter (53.75-57.5 (55) long); femur (107.5-112.5 (112.5) long); genu (92.5-103.75 (103.75) long); tibia (77.5-85 (85) long; 30-35 (35) wide); tarsus (20-25 (22.5) long). Palpomere proportions: femur/genu 1.08-1.22 (1.08); tibia/femur 0.69-0.77 (0.76); tibia length/width 2.36-2.67 (2.43).

Venter - (550-620 (580) long; 350-370 (370) wide) colorless and highly modified with coxae II–IV forming a large ventral plate that covers the insertions of legs IV. Suture dividing coxae III and IV incomplete. Apodemes expanded internally. Gnathosomal bay (110-115 (112.5) long; 90-110 (90) wide) expanded to accommodate large pedipalps. Cxgl-4 apical. Medial suture (155-165 (155) long). Genital plates (100-120 (105) long; 105-110 (105) wide) triangular. Additional measurements: Cx-1 (230-260 (250) long (total); 130-145 (130) long (medial)); Cx-3 (335-345 (335) wide); anterior venter (297.5-315 (300) long). Ventral proportions: gnathosomal bay length/width 1.05-1.25 (1.25); anterior venter/genital field length 2.63-2.98 (2.86); anterior venter length/genital field width 2.70-2.86 (2.86); anterior venter/medial suture 1.88-2.03 (1.94).

Immatures unknown.

Etymology.

Specific epithet ( dimorpha ) refers to the sexual dimorphism in terms of size and morphology (di, G. two; morphḗ, G. form), the resulting morphology is so unlike all other Torrenticolidae that upon first glance specimens appear to be a different family altogether.

Distribution.

Texas (probably also extending southward into Mexico) (Figure 56).

Remarks.

Torrenticola dimorpha groups with other members of the Tricolor Complex with high support and specimens of this species were less than 1% different in COI sequence from each other. In the combined analysis, T. dimorpha groups with T. larvata and these species are greater than 16% different in COI sequence from each other. This clade ( T. dimorpha + T. larvata ) is sister to all other eastern members of the Tricolor Complex.

This species is so unique that upon initial observation, specimens appear to be members of a different genus, especially the males. However, the short conical rostrum that is downturned in males is characteristic of other members of the Tricolor Identification Group.

This species hypothesis is supported by biogeography, high divergence between species, and by highly distinctive morphological characteristics outlined in the diagnosis. The high degree of sexual size dimorphism (males are 15-30% smaller than females) is only matched by most members of the Rusetria Complex, where males are usually 20-30% smaller than females.