A new species of rake-legged mite, Caeculus cassiopeiae (Prostigmata, Caeculidae), from Canada and a systematic analysis of its genus Author Bernard, Jared Invertebrate Zoology, Royal Alberta Museum, 9810 103 A Avenue NW, Edmonton, Alberta T 5 J 0 G 2, Canada & Plant & Environmental Protection Sciences, University of Hawaii-Manoa, 3050 Maile Way, Honolulu, HI 96822, USA https://orcid.org/0000-0003-4094-2839 bernardj@hawaii.edu Author Lumley, Lisa M. Invertebrate Zoology, Royal Alberta Museum, 9810 103 A Avenue NW, Edmonton, Alberta T 5 J 0 G 2, Canada Author Buck, Matthias Invertebrate Zoology, Royal Alberta Museum, 9810 103 A Avenue NW, Edmonton, Alberta T 5 J 0 G 2, Canada Author Cobb, Tyler P. Invertebrate Zoology, Royal Alberta Museum, 9810 103 A Avenue NW, Edmonton, Alberta T 5 J 0 G 2, Canada text ZooKeys 2020 926 1 23 http://dx.doi.org/10.3897/zookeys.926.48741 journal article http://dx.doi.org/10.3897/zookeys.926.48741 1313-2970-926-1 1BB22C603A7943E1A591C92EAC8B430F 6677D012D76F5C73894419DC46130BC6 Caeculus cassiopeiae Bernard & Lumley sp. nov. Figures 1 , 2 , 3 , 4 Material examined. Holotype . Canada • 1 ♀; Alberta, Medicine Hat, near Gas City Campground; 50°2.23'N , 110°43.56'W ; elev. ca 700 m; 26-27 Jul. 2014; M. Buck leg.; yellow pan traps; arid SW slope and adjacent disturbed plain of Agropyron cristatum and Medicago sativa ; det. J. Bernard and L. Lumley, 30 Aug. 2016; cleared in 85% lactic acid, dissected, and slide-mounted; PMAE M00019466. Paratype . Canada • 1 ♀; ibid.; stored in 95% EtOH; PMAE M00030967. Other material. Canada • 8 ♀♀; ibid.; 26 Jun. 2017; L. Lumley leg.; collected with paintbrush; hard dry soil surface; det. L. Lumley; stored in 95% EtOH; PMAE M00030972 to M00030979. Diagnosis. The five b setae on the centrodorsal opisthosoma are arranged in an M, three pairs of Pp setae are aligned on the posterior third of the aspidosoma, and trochanter III has three setae along anterolateral surface. Female description ( N = 2, all measurements in micrometres, μm ). Idiosoma dorsum (Figs 1 - 3 ). 1380-1592 = idiosomal length ( IL ); 1.920 x longer than greatest width (at level of posterior margin of mediodorsal opisthosomal sclerites) (718-829 = IW ). Sclerites tawny with pale ridges, ochre to raw sienna between sclerites, translucent white setae (Fig. 1A ). All clavate idiosomal setae barbed (Fig. 2C ). Rostral region with dark brown anteriorly projecting naso bearing one pair elongated clavate setae Po (74-94, ~0.054 x IL ), one median eye immediately inferior to base of naso (Fig. 3A ), one pair long, thickened attenuate bothridial seta bo (162-188, ~0.118 x IL ) with barbed distal end (Fig. 3C ), each inserted in anterolaterally projecting bothridium posterolaterad to median eye. Aspidosoma length 485-560 (0.352 x IL ), width 425-491 (0.592 x IW ) anterior to eyes, posterior margin of sclerite 309-357 (0.430 x IW ); pronounced furrow along length of medial axis containing three or four shallow longitudinal reticulated ridges, anterior furrow width 135-157 (~0.189 x IW ), posterior furrow width 102-118 (~0.142 x IW ), posterior furrow depth 35-41 (~0.050 x IW ); two pairs procurved clavate Pa setae on anterior margin; none or one pair clavate Pm setae near corners of anterior margin; three pairs clavate Pp setae medial to eyes on posterior lateral margins, aligned parallel to mid-sagittal plane; area around eyes dark, posterior eyes 1.077 x diameter of anterior eyes (Fig. 2A ), holotype with diminutive fourth Pp seta anterior to other three on right side. Centrodorsal opisthosomal sclerite trapezoidal, length 425-490 (0.308 x IL ), posterior margin 477-552 (0.665 x IW ); one pair clavate a1 setae near anterior margin of sclerite midway between mid-sagittal plane and lateral margins; 2.5 pairs clavate b setae: b1 pair anterior to mid-transverse plane and third of distance between mid-sagittal plane and lateral margins, b2 pair posterior to mid-transverse plane and midway between mid-sagittal plane and lateral margins, one unpaired median bs seta present between anterior and posterior pairs, the five setae together forming M-shape; one or two pairs clavate c setae along posterior margin (sometimes c1 , always c2 ) (Fig. 2A ). Laterodorsal opisthosomal sclerites each bearing five or six clavate setae in tandem, two ( a2 and a3 ) near anterior margin, one or two b setae at middle of sclerite (always b3 , sometimes b4 ), and two c setae near posterior margin ( c3 and c4 ); lyrifissure ia between a3 and b3 ; lyrifissure im between b4 and c3 (Fig. 2A ). Mediodorsal opisthosomal sclerites fused, bearing clavate d1 , d2 , and d3 setal pairs, with or without unpaired median clavate ds seta slightly anterior to these; posterior opisthosomal sclerite length 0.161 x IL , bearing clavate e1 , e2 , and e3 setal pairs and unpaired clavate es seta slightly anterior to these; lyrifissure ip near lateral margin between mediodorsal and posterior opisthosomal sclerites (Fig. 2A ). Pluriposterior accessory sclerite bearing three clavate setae, including one unpaired median clavate hs seta (Fig. 2B ). Figure 1. Caeculus cassiopeiae sp. nov., female A micrograph showing coloration B habitus illustrating cerotegument texture. Scale bar: 0.5 mm. Idiosoma venter (Fig. 2B ). Epimeres black to dark brown, cerotegument tawny, progenital valves dark sienna, aggenital sclerites raw sienna, adanal sclerites brown ochre, pseudanal sclerites raw sienna, translucent white setae. Epimeral setal formula (I-IV) 7-3-4-5. Epimeres I and II fused, anterior margin of epimere I bearing seven clavate setae, most proximal seta slightly less expanded than others and setae get progressively longer distally, distalmost ~76-120 (~0.071 x IL ), epimere II with three clavate setae along anterior margin; epimeres III and IV fused (separate from I + II), epimere III with three clavate setae along anterior margin and one clavate seta midway along proximal margin, epimere IV with one clavate seta at anteroproximal margin, one clavate seta on midline a third epimeral length from proximal margin, and three clavate setae along posterior margin (Fig. 2B ). Progenital valves ( PG ) each with seven smooth acuminate simple setae; aggenital sclerites ( AG ) each with three clavate setae; surrounding ventral cuticle bearing nine pairs of clavate setae, including pair ag1 between epimeres IV (Fig. 2B ). Adanal sclerites ( AD ) each bearing two clavate setae; pseudanal sclerites ( PS ) each with three clavate setae; one unpaired medial clavate seta posterior to anus; lyrifissure ih laterad to anterior pseudanal sclerite (Fig. 2B ). Figure 2. Caeculus cassiopeiae sp. nov., female idiosoma A dorsum B venter; PG , progenital valve; AG , aggenital sclerite; AD , adanal sclerite; PS , pseudanal sclerite C detail of bs seta, exemplifying typical clavate idiosomal seta. Scale bar: 0.5 mm ( A, B ). Gnathosoma (Figs 2B , 3A, B ). Palps black, chelicerae dark brown, subcapitulum black to dark sienna, translucent white setae. All clavate setae barbed, all simple setae smooth. Palps ( PA ) five-segmented, setal formula, trochanter-tarsus, solenidia ω and eupathidia ζ in brackets: 0-2-1-5-10(1 ω +1 ζ ); trochanter without setae; femur bearing two dorsal clavate setae midway along length, with proximal seta a third length of distal seta; genu bearing longest subclavate seta on tubercle at distal laterodorsal margin; tibia bearing five setae: one proximal anteroventral barbed spiniform seta, one laterodorsal spiniform seta with barbed distal end, one proximal dorsal elongated clavate seta, one distal dorsal barbed spiniform seta, and one posterolateral clavate seta (Fig. 3A ); well-developed tarsus (Fig. 3B ) bearing three dorsal smooth acuminate spiniform setae, one elongated spiniform seta with barbed distal end midway on ventral surface, one elongated barbed subclavate seta midway along posterolateral surface slightly distal to a minute solenidion ω recessed in large receptacle, one anterolateral smooth acuminate spiniform seta a third tarsal distance from distal end, one short smooth acuminate seta at distal posteroventral margin, two simple setae at distal end, and one eupathidium ζ posterior to one minute smooth spiniform seta at distal ventral margin. Chelicerae ( CH ) each with fixed digit regressed to lobe and movable digit uncinate (Fig. 3A ). Subcapitulum bearing two pairs of simple adoral or setae (Fig. 3A ) and two pairs of elongated thickened acuminate simple hypostomal setae m and n along base of hypostome, m medial to and slightly longer (53-63, ~0.039 x IL ) than n (Fig. 2B ). Figure 3. Caeculus cassiopeiae sp. nov., female A anterodorsal view of rostrum and gnathosoma B detail of palp tarsus C detail of distal bothridial seta. Abbreviations: CH , chelicera; PA , palp; bo , bothridial seta; d , dorsal; df , reduced fixed cheliceral digit; dm , movable cheliceral digit; ζ , eupathidium; hyp , hypostome; l ", posterolateral; ld , laterodorsal; me , median eye; Po , naso seta; ω , solenidion; v ', anteroventral; v , ventral; v ", posteroventral. Scale bar: 0.1 mm ( A ). Legs (Fig. 4 ). Black with translucent white setae. All clavate setae barbed, all rake/spiniform setae smooth. Formulae of leg setae (including rake setae), trochanter-tarsus, tarsal bothridial setae bt , solenidia φ / ω , eupathidia ζ , microseta κ ", and famulus ε in brackets: leg I 5/6-8+3(1 ζ )-21(2 ζ )-22(1 φ +1 ζ +1 κ ")-12(1 ω +5 ζ +1 ε ); leg II 5-10+4-16-17(1 φ )-14(1 ω +1 ε ); leg III 7-5+2(2 ζ )-9(1 ζ )-15(1 φ +1 ζ )-9(1 bt +1 ζ ); leg IV 7-2(1 ζ )+3(2 ζ )-9(1 ζ )-13(2 ζ )-13(1 bt +1 ω ). Leg I length 1301-1502 (~0.943 x IL ; Fig. 4A ); trochanter I bearing three procurved clavate setae on tubercles along anterolateral margin, two or three dorsal clavate setae; basifemur I with one rake seta on anteroventral margin and one rake seta on posteroventral surface; telofemur I with one rake seta on anteroventral margin and one eupathidium ζ a third the length from distal end on posteroventral margin; genu I with two anteroventral rake setae, one elongated anteroventral subclavate seta near proximal margin aligned with rake setae, three anterolateral clavate setae, one short anterolateral eupathidium ζ near distal margin, five clavate dorsal setae, five posterolateral setae with middle seta elongated subclavate and remainder clavate, one short eupathidium ζ near distal posterolateral margin, five posteroventral setae with most proximal clavate, followed by one rake seta and three elongated subclavate setae; tibia I with four anteroventral rake setae, one elongated spiniform seta near proximal anteroventral margin in line with rake setae, four anterolateral clavate setae, five clavate dorsal setae, four posterolateral clavate setae, three posteroventral rake setae, and one spiniform seta on posteroventral surface proximad to rake setae, and the following three near distal anterolateral margin, most distal to least: one microseta κ ", one recessed solenidion φ in large receptacle, and one eupathidium ζ ; tarsus I bearing four spiniform setae along each anterolateral, posterolateral, and posteroventral margins, one recessed solenidion ω in large receptacle situated a third the tarsal length from distal end on dorsal surface (Fig. 4E ), one famulus ε midway along anteroventral surface, and eupathidia ζ at the following locations: proximal dorsal surface, midway along posterolateral margin, a tenth the tarsal length from distal end on posteroventral margin, at distal anteroventral margin, and at distal anterolateral margin. Remaining clavate setation for leg I as in Fig. 4A . Chaetotaxy of other legs as in Fig. 4B-D . Basifemur II with one elongated barbed subclavate seta midway along posteroventral surface; genu II with one rake seta a third the distance along posteroventral surface; tibia II with three posteroventral rake setae, one dorsal solenidion φ near distal margin; tarsus II bearing one recessed solenidion ω in large receptacle a third length from distal end on dorsal surface, slightly distal to one anteroventral famulus ε (Fig. 4B ). Trochanter III with three anterolateral clavate setae and two or three dorsal clavate setae; tibia III with one solenidion φ near distal margin on dorsal surface (Fig. 4C ). Tarsi III and IV each with one elongated smooth slender bothridial seta bt a quarter of the length from distal margin on dorsal surface (125-145 [~0.091 x IL ] on tarsus III; 143-166 [~0.104 x IL ] on tarsus IV); tarsus IV with one solenidion ω a third the length from distal end on dorsal surface (Fig. 4C, D ). Tarsal claws on all legs equal in size. Male and immatures unknown. Figure 4. Caeculus cassiopeiae sp. nov., female A-D dorsal view of legs I-IV E detail of solenidion ω on tarsus I. Scale bar: 0.5 mm ( A-D ). Abbreviations: ε , famulus; ζ , eupathidium; κ ", microseta; φ , tibial solenidion; ω , tarsal solenidion; bt , tarsal bothridial seta; d , dorsal; l ', anterolateral; l ", posterolateral; v ', anteroventral; v , ventral; v ", posteroventral. Etymology. The b setal arrangement on the centrodorsal opisthosoma resembles the five-star constellation named for Cassiopeia, the vain wife of King Cepheus in Greek mythology. The constellation is also known as the "Celestial M" given its orientation to the horizon when it ascends in the night sky on its arc around Polaris, and is known as the "Celestial W" as it sets. Cassiopeia's rise is most observable in the evenings during northern autumns. The genitive epithet abides by Articles 11.9.1.3 and 31.1.2 of the International Code of Zoological Nomenclature, and hence means "Cassiopeia's rake-legged mite." Ethology. We observed individuals both walking and motionless with legs I positioned in a raptorial manner above the soil surface. A captive individual consumed a prostigmatan we collected from the same exposed soil.