Protectoribates, Behan-Pelletier, 2017

Behan-Pelletier, Valerie M., 2017, Tegoribatidae of North America, with proposal of Protectoribates gen. nov., and new species (Acari, Oribatida, Tegoribatidae), Zootaxa 4337 (2) : 153-155

Protectoribates gen. nov.

Figs. 1–7

Type species: Protectoribates occidentalis sp. nov.

Diagnosis. Adult. With character states of Tegoribatidae ( Grandjean (1953, 1954), Woolley (1965) Fredes & Martínez (2016), and see below). Species comprising this genus are unique among poronotic Brachypylina ( Grandjean 1954) by having the following combination of character states. Rostrum with medial keel extending posteriorly; rostrum rounded anteriorly, without medial incision. Lamella long, fused, with V-shaped indentation anteriorly, covering all of prodorsum in dorsal aspect, without longitudinal line medially. Tutorium narrow lamelliform, cusp triangular. Genal tooth well-developed, pointed distally, with ridge along length. Bothridium with lateral and medial scales. Porose areas Ad and Am present, Al absent, Ah expressed as deep, round saccule. Dorsophragmata medially separated. Octotaxic system as 4 pairs of porose areas. Notogaster with non-overlapping posterior tectum. Pteromorph well-developed, without hinge; lenticulus absent; hexagonal pattern absent anteriorly on notogaster. Notogaster with 10 pairs of setae; setae not apobasic. Epimere I without necklace of tubercles. Epimeral setation 3-1-3-3. Custodium broadly rounded distally, or not. Sejugal apodeme and apodeme 3 welldeveloped. Genital setation 6 pairs, with 3 setae along anterior margin of each plate. Band of darkened integument posterior to genital plates. Postanal porose area absent. Subcapitulum diarthric, without tectum on mentum. Axillary saccule present. Legs monodactylous. Tibia II with large, dentate carina anterodorsally. Tibia IV with solenidion. Femur I without bend at level of seta d.

Juvenile instars Apheredermous; line of dehiscense incomplete; integument plicate, without hysterosomal macrosclerites or excentrosclerites, cerotegument as tightly packed platelets, 1 in diameter, covering all of body and leg segments. Prodorsal porose region present. Gastronotal setation unideficient; nymphs with 15 pairs of setae (f1 absent). Gastronotal setae of c, d, l and p series monomorphic, short, without barbs, acuminate ( Fig. 6 ). Rostral, lamellar, and interlamellar setae subequal to gastronotal setae.

Description. Adult. Integument. Cerotegument present laterally on podosoma, finely and densely granulate ( Fig. 5E ). Integument microtuberculate throughout; U-shaped depression extending from coxisternal region to posterior of anal plates ( Fig. 5B ).

Prodorsum. Rostrum with smooth margin, without medial incision ( Fig. 5C ); broadly rounded keel extending from margin posteriorly to underneath lamella ( Figs. 5C, D ). Rostral seta heavily barbed laterally, directed anteromedially ( Fig. 3 ). Lamella long, pair fused, covering all of prodorsum in dorsal aspect ( Figs. 1 , 5A ), without longitudinal line medially; nerve canal for seta le evident ( Fig. 7A ). Seta le arising anterodorsally on lamella. Fused lamella with short, V-shaped indentation anteriorly; concave posterolaterally, accommodating bothridium ( Figs. 1 , 7A , and insert). Translamella absent. Exobothridial seta present (alveolus only indicated on Fig. 3 ). Bothridial wall expanded medially and laterally, with scales, without lateral indentation ( Fig. 7A , insert). Porose area Ad present. Dorsophragmata separate ( Fig. 1 ).

Notogaster. Longer than wide; with immovable pteromorphs having smooth margins, without dens anteroventrally ( Fig. 5B ). Anterior margin straight, transverse, without ridges in region lateral to bothridium ( Figs 1 , 5A ). Without subsurface anteromedial hexagonal pattern. Octotaxic system expressed as 4 pairs of porose areas ( Fig. 1 ); without sexual dimorphism. With 10 pairs of short setae; distance h1-h1 wider than distance p1-p1.

Lateral Region of Podosoma. Genal tooth, pointed triangular, with longitudinal ridge ( Figs. 3 , 5E ). Tutorium narrow, lamelliform, lying parallel to dorsal contour of prodorsum in lateral aspect, seta ro inserted at base of tutorial cusp ( Figs. 3 , 5D ). Pedotectum I convex dorsally, without ventral depression ( Fig. 3 ). Pedotectum II present, without tubercle close to body wall. Custodium present, with long, free distal region, broadly rounded or not ( Figs. 3 , 7B ). Discidium strongly curved lamina ( Figs. 3 , 7B ). Porose area Al absent. Humerosejugal porose organs Am and Ah present, Am porose area, Ah saccule ( Figs. 7C, D ).

Ventral. Epimere I without anterior necklace of small tubercles. Epimeral setal formula 3-1-3-3. Genital plates with 6 setae, 3 on anterior margin; 1 pair aggenital setae; 3 pairs adanal setae and 2 pairs anal setae ( Fig. 2 ). Lyrifissure iad at anterolateral edge of anal plate. Postanal porose area absent. Band of darker integument extending transversely between genital and anal plates ( Fig. 2 ).

Gnathosoma . Chelicera chelate-dentate. Mentum without tectum, without recurved ridge distally ( Fig. 5E ). Palp setal formula 0-2-1-3-9(1); eupathidium acm shorter than solenidion, forming double horn with solenidion along length, but partially separated basally (as in Tectoribates Behan-Pelletier & Walter 2013 , their Fig. 7E ).

Legs. Monodactylous ( Figs. 4A–C ). Leg setal formula I–IV, solenidia in parentheses: I: 1-5-3(1)-4(2)-20(2); II: 1-5-3(1)-4(1)-15(2); III: 2-2-1(1)-3(1)- 15; IV: 1-2-2-3(1)-12. Genua I and II without tooth ventrally ( Figs. 4A, B ). Porose areas on femora I to IV and trochanters III and IV. Femur I without bend medially at level of seta d. Tibia II with anterodorsal dentate carina ( Figs. 4B , 5D , 7E ). Seta s on tarsus I eupathidial, positioned distal to setae (a).

Solenidia on tarsus II shorter than setae on segment ( Fig. 7E ); ω1 not most proximal setiform structure on segment. Femur III with seta l’ absent (2 setae); seta v' of genua I and II present. On genua and tibiae I and II setae l” subequal in shape to l’, setiform ( Figs. 4A, B ). Seta pv” on tarsus II, comb-like ( Fig. 7E ). Anterodorsal knobs or spines absent from tibia I.

Etymology. The derivation of Protectoribates is from the Latin ‘protector’, meaning "protector", and ‘oribates’ from Greek, a common ending for generic names in Tegoribatidae . It refers to a possible function of the dentate carina on tibia II.

Remarks. Adults of Protectoribates are distinguished from those of all other genera by having the combination of: dentate carina on tibia II, gnathosoma without tectum on mentum, pteromorphs without hinge, Ah developed as saccule; band of darkened integument posterior to genital plates, postanal porose area absent ( Table 4). Among these traits, the dentate carina on tibia II and the form of humerosejugal organ Ah are considered apomorphic.

Immatures of Protectoribates are similar to those of Tectoribates ( T. alcicampestris Behan-Pelletier & Walter, 2013 and T. borealis Behan-Pelletier & Walter, 2013 ) in being plicate, apheredermous with monomorphic hysterosomal setae of series c, d, l, and h. Hysterosomal setae of immature Hypozetes laysanensis Aoki, 1964 are also monomorphic, but larval seta dp are twice the length of other hysterosomal setae and are borne on distinct tubercles ( Behan-Pelletier 2001). Similarly, in larva and nymphs of Plakoribates multicuspidus Popp, 1960 hysterosomal setae are monomorphic in shape, but seta dp are twice the length of other hysterosomal setae and are also borne on distinct tubercles ( Shereef 1977). In contrast, known immatures of Tegoribates are plicate and eupheredermous, integridorsal (retain centrodorsal setae) and hysterosomal setae are dimorphic (see below).

Figures

FIGURE 1. Protectoribates occidentalis sp. nov., adult female, dorsal aspect, legs not illustrated; dorsophragmata indicated by arrows. Scale bar = 50 µm.

FIGURES 2 – 3. Protectoribates occidentalis sp. nov., adult female, legs not illustrated; 2, ventral aspect; 3, lateral aspect, only alveolus of seta ex illustrated, gnathosoma not illustrated. Scale bar = 50 µm.

FIGURE 4. Protectoribates occidentalis sp. nov., adult female, A, leg I, B, leg II, C, leg IV, all antiaxial aspect. Legs I and II, trochanter not illustrated. Scale bar = 20 µm.

FIGURE 5 A – E. Protectoribates occidentalis sp. nov., scanning electron microscope images of adult female from California; A. habitus dorsal; B, habitus ventral, with arrow to custodium; C, frontal aspect; D, dorsolateral of prodorsum, with arrow to spindle end of bothridial seta (bo), second arrow to genal incision and third arrow to carina on tibia II; E, ventrolateral of prodorsum, with arrow to ridge on genal tooth. Scale bars: A, B = 25 µm, C – E = 15 µm.

FIGURE 6. Protectoribates occidentalis sp. nov., tritonymph, dorsal aspect. Scale bar = 50 µm.

FIGURE 7. Protectoribates occidentalis sp. nov., differential interference contrast microscope images, A – E adults; A, bothridium and bothridial seta (5 layers), with arrow to nerve canal of seta le on lamella; insert of bothridium showing scales; B, custodium and discidium (3 layers), with arrow to broad, rounded anterior edge of custodium; C, porose organ Ah, lateral view, with arrow to surrounding cerotegument (3 layers); D, dissected specimen with Ah in direct view (2 layers); E, genu, tibia and tarsus II, with white arrow to dentate carina on tibia (2 layers) and narrow black arrow to seta pv ”; F, protonymph (2 layers), dorsal view. Scale bar: A = 25 µm; B = 10 µm; D = 7.5 µm; F = 50 µm.