Crenubiotus revelator, Lisi & Londoño & Quiroga, 2020

Lisi, Oscar, Londoño, Rosana & Quiroga, Sigmer, 2020, Description of a new genus and species (Eutardigrada: Richtersiidae) from Colombia, with comments on the family Richtersiidae, Zootaxa 4822 (4), pp. 531-550 : 543-547

publication ID	https://doi.org/ 10.11646/zootaxa.4822.4.4
publication LSID	lsid:zoobank.org:pub:E19991A3-2DFA-4127-8A5E-DCA6687533A0
DOI	https://doi.org/10.5281/zenodo.4450336
persistent identifier	https://treatment.plazi.org/id/876987F7-8A61-FFA1-FF05-7074FB644515
treatment provided by	Plazi
scientific name	Crenubiotus revelator
status	sp. nov.

Treatment

Crenubiotus revelator sp. nov.

( Figs 8–9 View FIGURE 8 View FIGURE 9 , Table 3)

Material examined: 65 specimens deposited in the Centro de Colecciones Científicas de la Universidad del Magdalena: CBUMAG:TAR:00067 (4 specimens), 00069 (1 specimen), 00073 (10 specimens), 00074 (2 specimens), 00075 (1 specimen), 00076 (1 specimen), 00092 (10 specimens), 00093 (10 specimens), 00094 (13 specimens), 00096 (12 specimens), and 00403 (1 egg). Localities: San Lorenzo GoogleMaps 11°06’20.0’’N, 74°03’50.0’’W, 2284 m asl (type locality), and Bella Vista 11°05’47.8’’N, 74°05’04.4’’W, 1930 m asl. Complete information with correspondence between localities, sample kinds, type material and slide numbers, is given in Table 1.

Type repositories: Holotype, CBUMAG:TAR:00092-1. 32 Paratypes: CBUMAG:TAR:00092 (9 specimens), 00093 (10 specimens), 00094 (13 specimens), 00403 (1 egg).

Species diagnosis: Colourless after mounting, eye-spots present. Cuticle with circular and elliptical pores, in all life stages, of various sizes, global diameter pt range about 0.5–6.3; the smallest pores are rounded and sparse on the body, while the biggest are elliptical and present caudally as well as a cephalic pair present laterally to the mouth. Small cuticular tubercles present in a dorso-lateral caudal band just anterior to the hind legs, on the dorsal cuticle of such legs, and, less evident, on all legs on the dorsal and lateral leg cuticle (both externally and internally) and some between the claws. Simple buccal armature: no anterior or posterior bands of teeth visible under light microscopy, only lateral transverse crests, dorsal and ventral, the former ending each into a tooth in their median extremity; a medio-ventral tooth present between the two crests. Slender buccal tube, pt of its width about 10, pt of the stylet supports insertion point about 74. Two macroplacoids plus microplacoid. Claws typical for the genus, slender; large lunules on all legs with long, thin teeth equal to one another and uniformly distributed.

Eggs with conical, very finely and delicately reticulated processes. They are constituted by a main body and a tip more slender provided with darker papillous surface; tip sometimes containing internal septa delimiting a single proximal “bubble” plus eventual smaller, more distal ones. Tips sometimes ending with a filament. Base of processes with narrow projections on the egg shell, frequently connecting to each other from different adjacent processes.

Description of the holotype: Body length 359 µm, colourless after mounting. Eye-spots present. Cuticle with circular and elliptical pores, the largest are a very cephalic pair, elliptical, lateral to the mouth (minor × major diameter 1.51 µm × 2.22 µm; pt = 3.8 × 5.6) and the very the caudal, also elliptical (major diameter up to 1.61 µm, pt = 4.2); the smallest pores, instead, rounded and sparsely distributed on the cuticle, have diameter starting from less than about 0.5 µm (it was difficult to measure precisely such small structures; pt less than about 1.3). The pores are present in all life stages and seem not to show allometric growth.

Small cuticular tubercles form a dorso-caudal band ( Fig. 8D View FIGURE 8 arrows a), on the dorsal side of legs IV ( Fig. 8D View FIGURE 8 arrow b), and, smaller, on all legs ( Fig. 9A View FIGURE 9 arrows, 9C arrow), giving a dotted appearance, on the dorsal and lateral leg cuticle (both externally and internally) and some between the claws. Bucco-pharyngeal apparatus ( Fig. 8A View FIGURE 8 ) of modified ‘ Macrobiotus type’, i.e. with ten peribuccal lamellae, rigid buccal tube with ventral lamina which is provided with an additional ventral thickening on its anterior portion, appearing as a ridge, laterally ( Fig. 1A View FIGURE 1 arrow a, in a paratype), as an elongated trapezoidal structure pointing forward ventrally ( Fig. 1C View FIGURE 1 arrow, in a paratype); stylet furcae with the thickened, swollen apices of the branches very developed and elongated laterally ( Fig. 1E View FIGURE 1 arrow, in a paratype). Buccal armature ( Fig. 8B, C View FIGURE 8 ) seemingly without anterior and posterior bands of teeth (not visible, at least under light microscopy); crest system present but represented only by the lateral crests, with dorsal lateral crests which form each at the medial extremity a thickening similar to a tooth ( Fig. 8B View FIGURE 8 arrow, in a paratype). A proper median tooth present only ventrally between the crests, slightly in a more anterior position ( Fig. 8C View FIGURE 8 arrow, in a paratype).

Pharynx with apophysis, two rod-shaped macroplacoids, the first with central constriction, the second with slight, subterminal constriction, and microplacoid ( Fig. 8A View FIGURE 8 ).

Claws typical of the genus, slender with long base and common portion; main branches with accessory points; very big lunulae, typically indented (long and thin teeth equal to one another and uniformly distributed) ( Figs 2 View FIGURE 2 , 3 View FIGURE 3 , 9 View FIGURE 9 ).

Egg ( Fig. 8E View FIGURE 8 ) white, spherical, with conical processes constituted by a main body and a distal portion more slender provided with darker, minutely papillous/hairy surface ( Fig. 8F View FIGURE 8 arrow a); the tips sometimes end with a filament eventually frayed ( Fig. 8 View FIGURE 8 E-G). The distal portion may contain internal septa delimiting a single proximal “bubble” plus eventual smaller more distal ones ( Fig. 8G View FIGURE 8 arrow). A very minute, delicate reticular design, difficult to see and to show on photos, can be observed on the main body of the processes (barely visible in Fig. 8G View FIGURE 8 ), while their bases form thin projections on the eggshell, usually long, that may in some cases connect to one another between adjacent processes ( Fig. 8F View FIGURE 8 arrow b, H arrow), but without forming areolation or reticulation.

The only egg found has a diameter of 97.8 µm including the processes, 78.1 µm excluding them; 45 processes are present on the hemisphere, 16 on the optical section; the processes are high 14.0– 16.8 µm and have a basal diameter of 10.6–14.0 µm (most processes are about 15 µm high and 11 µm wide at their base).

In Table 3 the measurements of selected morphological structures of the holotype, and relative pt indices, and the ranges among the measured type specimens, are provided.

Taxonomic remarks: The paratypes show the same characteristics of the holotype in both qualitative and metric characters, with very low morphometric variability ( Table 3). The only egg found is not embryonated but it is definitely the same type as that of C. crenulatus , with just minor differences at sibling species level, and the absence of other Macrobiotoidea taxa in the sample allowed us to attribute it to the specimens found.

Differential diagnosis: C. revelator sp. nov. is very similar to C. crenulatus comb. nov., but it differs from it in having smaller cuticular pores on all the body; in particular, C. revelator has pt of minor × major diameter of the cephalic elliptical pore pair 3.8 × 5.6 (holotype; vs 7.4 × 8.5 in the neotype of C. crenulatus comb. nov.), pt of the diameter of the smallest pores (it was difficult to measure precisely such small structures) less than 0.5 (vs at least 0.7 in C. crenulatus comb. nov.), pt of major diameter of the biggest elliptical pores (which were located posteriorly) 4.0–6.3 vs 7.5–9.9 in C. crenulatus comb. nov. The new species has a medio-ventral tooth in the buccal armature (absent in C. crenulatus comb. nov.), more slender buccal tube (pt = 9.6–11.0 in the new species, about 13.2–14.4 in C. crenulatus comb. nov.), slightly more caudal stylet supports (pt = 73.2–74.8 in the new species, vs. about 71.9–72.8, slightly more slender claws (compare Figs. 2 View FIGURE 2 and 3A, B View FIGURE 3 for the new species with Figs. 3C View FIGURE 3 and 6F, G View FIGURE 6 for C. crenulatus comb. nov.) and in details of the egg (compare Fig. 7 View FIGURE 7 with Fig 8 View FIGURE 8 E–H): the processes are usually more slender in the new species and more often the main body of the process continues gradually in the tip, without the abrupt passage observed in C. crenulatus comb. nov.; the tips are more regular being very slender cones without irregularities or branches; these tips appears less transparent in the new species, being usually covered by a sort of extremely fine down, and often show internally a basal “bubble” eventually followed by other smaller (the basal bubble is more rare in the egg processes of C. crenulatus comb. nov., and additional smaller bubbles were not observed in this species). The distal filament is thicker and usually not frayed, while it is instead very often in C. crenulatus comb. nov. Process bases forms projections on the shell which are more developed in the new species and are frequently connected (not so in C. crenulatus comb. nov.).

See the end of former paragraph “Remarks on Crenubiotus crenulatus comb. nov. ” about possible confusion between the egg of the new species with eggs of the Mesobiotus coronatus group.

Etymology: The specific name “ revelator ” (= one who reveals) refers to the fact that the specimens of the new species revealed the existence of the new genus and the belonging to it of the former M. crenulatus .