Trichoribates Berlese, 1910

Behan-Pelletier, Valerie M. & Ermilov, Sergey G., 2019, Trichoribates sidorchukae sp. nov. (Acari, Oribatida, Ceratozetidae) from tropical montane Ecuador, with revised generic diagnosis, Zootaxa 4647 (1), pp. 348-361 : 349-351

Genus Trichoribates Berlese, 1910

Type species Sphaerozetes (Trichoribates) berlesei Jacot, 1929

Revised diagnosis

Adult. With character states of the Ceratozetidae ( Grandjean 1953) . Integument: Smooth, or striate, or microtuberculate, or microfoveate. Color yellow to dark brown. Body and leg segments with or without granulate cerotegument. Prodorsum: Rostrum rounded to flattened; serrate or not, with or without small lateral dens; with or without rostral bulge. Lamella narrow to wide, with well-developed cusp, cusp with or without lateral and medial dens. Translamella weakly to well-developed. Tutorium broad, blade-like, with cusp pointed or dentate distally, usually extending anterior to base of rostral seta; covering base of rostral seta or not. Bothridium generally cup-shaped, with or without medial, pointed scale; partially to completely covered by anterior margin of notogaster. Bothridial seta with clavate to globular head, rounded or flattened distally; stalk short to long. Notogaster: Anterior of notogaster forming tectum, usually covering at least base of bothridium. Pteromorph immovable, large, curved ventrally, generally without, rarely with partially desclerotized linear region (“hinge”). Lenticulus absent or present. Posterior notogastral tectum absent. Octotaxic system usually as four pairs of porose areas, occasionally as five (two pairs of A1) pairs of porose areas, or as three pairs of saccules. Five pairs of lyrifissures present. With 10 or 11 pairs of notogastral setae, c 1, c 2, da, and dm always absent, dp absent or present. Gnathosoma . Chelicera chelate-dentate. Trägårdh’s organ tapered. Palps with setation 0-2-1-3-9(+ω). Solenidion of palptarsus bacilliform, attached to acm. Axillary saccule present. Lateral podosomal and epimeral regions: Pedotectum I as large lamina, usually convex dorsally, generally rounded distally. Genal tooth elongate, triangular. Custodium short, broad. Discidium triangular. Circumpedal carina long, directed to custodium. Porose areas Ad, Am and Ah present, Al absent or present. Horizontal folds in integument present between and dorsal of acetabula I and II. Apodemes 1, 2, sejugal and 3 well sclerotized. Epimeral setal formula: 3-1-2-2, 3-1-3-1, 3-1-3-2 or 3-1-3-3; setae 1c usually longer, thicker, and more heavily barbed than other epimeral setae. Anogenital region: Five or six pairs of genital, one pair of aggenital, two pairs of anal and three pairs of adanal setae. Postanal porose area present, long and narrow. Legs: All legs heterotridactylous; median claw distinctly thicker than lateral claws, all claws slightly barbed dorsally. Tibia I with dorsodistal apophysis bearing solenidion φ 2, as well as apophysis bearing solenidion φ 1. Setae l” of tibiae I, II and genua I, II, and sometimes that of other tibiae and genua thick, heavily barbed. Seta l’ on femora III present or absent. Genu I with or without ventrodistal projection. Porose areas present on all femora and on trochanters III, IV. Porose areas present proximoventrally on tarsi I–IV and distoventrally on tibiae I–IV, or absent.

Juvenile instars. Humeral organ present or absent; likely absent in larva and present in nymphs. Gastronotal region of nymphs with or without large pygidial sclerite (PY) bearing setae of d, 1, and h series. Gastronotic setae of c series inserted on individual small sclerites, or on unsclerotized integument; with large, heavily pigmented lateral sclerites surrounding opening of sclerotized opisthonotal glands, separated from PY (when present) by unsclerotized integument. Twelve pairs of gastronotal setae in larva (c, d, l, and h series); nymphal instars with 15 pairs (c, d, l, h, and p series).

Remarks

1. It has been informally suggested in an unpublished online document ( Subías 2019) that the genera Laminizetes Behan-Pelletier, 1986 , Viracochiella Hammer, 1961 and Leebates Balogh & Mahunka, 1996 are subgenera of Trichoribates , a suggestion we reject. In Viracochiella tuberculata Hammer, 1961 , the type species, the anterior of the notogaster extends only over the base of the bothridium and the bothridium has a strongly developed lateral scale, character states not present in known Trichoribates . Similarly, in Laminizetes fortispinosus Behan-Pelletier, 1986 , the type species, the anterior of the notogaster extends only over the base of the bothridium, the bothridium has strongly developed medial and lateral scales, and horizontal folds are absent between and dorsal of acetabula I and II. In Leebates bornemisszai Balogh & Mahunka, 1996 , the type species, the anterior of the notogaster does not extend over the bothridium and the bothridium has a strongly developed lateral scale. Balogh & Mahunka (1996) did not attribute this genus to any ceratozetoid family, their illustrations show the presence of a posterior notogastral tectum, and thus, it is not a member of the Ceratozetidae ( Grandjean 1953) .

2. Trichoribates and Diapterobates Grandjean, 1936 are typically recognized as discrete genera of Trichoribatinae Shaldybina, 1966, but Trichoribates polaris Hammer, 1953 confounds their distinction. Characters differentiating the genera are: notogastral setae ( Trichoribates , 10–11 pairs; Diapterobates , 13 pairs); pteromorphs unsclerotized band (hinge) ( Trichoribates , absent; Diapterobates , present). Whereas Trichoribates polaris has 10 pairs of notogastral setae, but uniquely in Trichoribates has pteromorphs with a line of desclerotization extending almost to the level of seta c ( Behan-Pelletier 1985). In addition T. polaris has pedotectum I concave dorsally (as in Svalbardia paludicola Thor, 1930 ) and subcapitular mentum with a narrow tectum overhanging the genae; this combination of character states is not found in other species of Trichoribates or Diapterobates .

Adult T. polaris express absence of seta 1’ from femur III, a character state shared with Trichoribates monticolus ( Trägårdh, 1902) , Trichoribates ocotlicus Palacios-Vargas & Norton 1984 , Trichoribates punctatus Shaldybina, 1971 , Trichoribates scilierensis , Trichoribates spatulasetosus Reeves, 1967 , Trichoribates tepetlensis Palacios-Vargas & Norton 1984 , and T. sidorchukae sp. nov., described below; this loss is also expressed in Svalbardia paludicola .

Juvenile instars of T. polaris share the absence of humeral organ from the larva and its presence in nymphs with T. tepetlensis and T. ocotlicus (not illustrated in figures 11, 13 of Palacios-Vargas & Norton (1984)). Other than the humeral organ being generally absent in immature Diapterobates , no character state separates juveniles of these genera (Shaldybina 1965, Seniczak 1980, 1993 a, b; Bayartogtokh & Ermilov 2016).

As the line of desclerotization on the pteromorphs in adults of T. polaris is as well developed as that found in specimens of Diapterobates , and is the character most commonly used to separate Diapterobates from Trichoribates in keys (e.g., Weigmann 2006), it is evident that relationships between these genera and others in Trichoribatinae need phylogenetic (or molecular) analysis similar to that for Galumnoidea by Klimov & Ermilov (2017).

3. Michael (1888) noted the variability in length of lamellar cusps in populations of one species of Trichoribates from England. Weigmann & Norton (2009) considered that this variability may refer to more than one species. Similarly, Pavlichenko (1991 b) studied variability in rostral and lamellar shape in about 200 specimens of Trichoribates trimaculatus Koch, 1835 from Ukraine and noted that rostral shape varied from flattened with lateral dens to rounded, and lamellar shape varied from medial and lateral dens equal in size to specimens with medial dens absent. Clearly, character states other than shape of the rostrum and lamellae need to be included in descriptions.

4. Humeral organs, secretory porose organs, first discovered by Grandjean (1953) are characteristic of juvenile instars of many species in the Ceratozetidae ( Alberti et al. 1997; Bayartogtokh & Ermilov 2016). Their occurrence in other families in the Ceratozetoidea, and in the Oribatelloidea, Phenopelopoidea, and Galumnoidea ( Grandjean 1953), has led Palacios-Vargas & Norton (1985) to hypothesize that they are pleisiomorphic among poronotic Brachypylina. Shaldybina (1971, 1972) considered them absent from the Trichoribatinae, and Seniczak (1980) made no mention of these organs in his descriptions of the juveniles of Trichoribates trimaculatus and T. novus ( Sellnick, 1928) . Seniczak & Seniczak (2011) described their presence in nymphs of Umbellozetes slaveki Seniczak & Seniczak, 2011 , which they considered a trichoribatine; Bayartogtokh & Ermilov (2016) mistakeningly noted them as absent from this species. As indicated above, they are known for nymphs of T. polaris , T. tepetlensis and T. ocotlicus . They are absent in juvenile instars of Dentizetes Hammer, 1952 , Iugoribates Sellnick, 1944 and Diapterobates notatus ( Thorell, 1871) ( Behan-Pelletier 1986) .

5. The strong horizontal folds in the integument between and dorsal of acetabula II and III may be an apomorphy of Trichoribatinae within the Ceratozetidae . They are present in T. sidorchukae sp. nov. (described below) and in all other species of Trichoribates where this character has been examined – Trichoribates copperminensis Hammer, 1952 , Trichoribates monticolus , Trichoribates ogilviensis Behan-Pelletier, 1986 , T. polaris , Trichoribates scilierensis Bayartogtokh & Schatz, 2008 , and Trichoribates striatus Hammer, 1952 ( Bayartogtokh & Schatz 2008). They are also found in the genera Svalbardia Thor, 1930 , Diapterobates , Dentizetes and Neogymnobates Ewing, 1917 ( Behan-Pelletier 1986). They have not been found in other genera of Ceratozetoidea examined so far.

6. Presence or absence of axillary saccules of the subcapitulum is a character state overlooked in most descriptions. It is a character state of Trichoribates (see generic diagnosis above), and also found in Diapterobates ( Bayartogtokh & Ermilov 2016) .

7. We transfer Trichoribates neglectus Kulijev, 1979 to Sphaerozetes ( Sphaerozetes neglectus ( Kulijev, 1979)) , as informally proposed by Subías (2019). The illustration of this species ( Kulijev 1979) shows that much of the bothridium is exposed, i.e., not covered by the anterior margin of the notogaster. It also shows the tutorium as a short structure, far removed from the base of rostral setae anteriorly.