Diploplastron dehorityi, Cedrola, Franciane, Dias, Roberto Júnio Pedroso, Martinele, Isabel & D’Agosto, Marta, 2017

Cedrola, Franciane, Dias, Roberto Júnio Pedroso, Martinele, Isabel & D’Agosto, Marta, 2017, Description of Diploplastron dehorityi sp. nov. (Entodiniomorphida, Ophryoscolecidae), a new rumen ciliate from Brazilian sheep (Ovis aries), Zootaxa 4258 (6), pp. 581-585 : 582-583

Diploplastron dehorityi sp. nov. ( Fig. 1 a–f; Table 1)

Description. Diploplastron dehorityi presents an oval body (body length: 79.0 ± 4.1 µm [mean ± SD] body width 57.7 ± 2.9 µm and length / width: 1.3 ± 0.05 µm) laterally compressed with a prominent lobe in the posterior end ( Fig. 1 a). The external surface has small longitudinal striations. The vestibule is small and only slightly evident ( Fig. 1 a and f). Two retractable ciliary zones, one adoral and other dorsal, are in the same plane in the anterior end of the body and are separated by a slightly flattened protuberance, the operculum ( Fig. 1 a and f). Two slender and curved skeletal plates on the right side of the body depart from the base of the adoral ciliary zone and continue up to the final third of the body ( Fig. 1 a and f), juxtaposed to the ventral surface of the macronucleus. The skeletal plate in the base of the adoral ciliary zone is spaced (distance of approximately 6.5 µm), and in the middle region of the body, it is close. After the median approximation, they separate (distance of approximately 5.7 µm), returning to approximate the final portion. The macronucleus is rod-shaped, slightly curved (macronucleus length: 53.9 ± 2.7 µm), and has a small depression on the dorsal surface, whereas the micronucleus has an elliptical shape ( Fig. 1 a). Two contractile vacuoles, with inconspicuous excretory pores, are located dorsally to the macronucleus. The rectum is a tubular structure located in the posterior end of the body and opens by a small pore, the citoproct ( Fig. 1 a).

The oral infraciliature in D. dehorityi corresponds to the Diplodinium-type ( Ito & Imai 2006) ( Fig. 1 b and f). This pattern consists of an adoral polybrachykinety (AP), vestibular polybrachykinety (VP), dorsal polybrachykinety (DP), and paralabial kineties (PK). AP involves the buccal opening, and VP is long and extends into the vestibule, if originating internally by the dorsal side of AP. DP extends laterally along the dorsal side of the body and PK, ranging in number from four to five, and is located close to the ventral portion of AP.

Remarks. Diploplastron dehorityi sp. nov. resembles Diploplastron affine ( Fig. 1 g–j) in number of contractile vacuoles and number of skeletal plates. However, they differ in body and macronuclear size [body length: 79.0 ± 4.1 ( D. dehorityi ) versus 94.0 ± 0.7 ( D. affine ); body width: 57.7 ± 2.9 ( D. dehorityi ) versus 63.1 ± 0.6 ( D. affine ); macronuclear length: 53.9 ± 2.7 ( D. dehorityi ) versus 64.9 ± 1.1 ( D. affine )] body shape, macronuclear shape and shape of skeletal plates. In addition, D. dehorityi presents less length: width ratio that D. affine [1.4 ± 0.05 ( D. dehorityi ) versus 1.4 ± 0.02 ( D. affine )] ( Table 1). The new species resembles, also, the species Eremoplaston neglectum (Dogiel 1925) and the species E. rotundum ( Kofoid & MacLennan 1932) in size and body shape, presence of a lobe in the posterior end, macronucleus shape, and number of contractile vacuoles. However, it differs in the number of skeletal plates, as ciliates belonging to the genus Eremoplastron possess only a single skeletal plate.

Habitat, type host, and type locality. The rumen of Brazilian domestic sheep ( Ovis aries L.) in Frei Paulo, Sergipe, Brazil (10.518317 S, 37.651118 W) .

Etymology. The name of the new species was selected in honor of the late Dr. Burk A. Dehority, The Ohio State University, a leading rumen microbiologist and rumen ciliate taxonomist.

Type material. Slides of the holotype (C_Dd_0001_01) and paratype (C_Dd_0001_02 and 03) will be deposited in the collection of the Laboratório de Protozoologia (LabProto), Universidade Federal de Juiz de Fora, Minas Gerais, Brazil .

Occurrence and ecology. Diploplastron dehorityi sp. nov. were observed in one of the 32 sheep analyzed (prevalence of 3.1%) and in a density of 0.8 × 10 4 protozoa/ml of rumen contents and without co-occurring with Diploplastron affine . In this animal host, we observed also species belonging to the genera: Dasytricha Schuberg , Diplodinium Schuberg , Charonina Strand, Enoploplastron Kofoid & MacLennan , Entodinium Stein , Isotricha Stein , Metadinium Awerinzew & Mutafowa , Ophryoscolex Stein and Polyplastron (Dogiel) . D. affine was observed in 17 of the 32 sheep analyzed (prevalence of 53.12%) and in average density of 1.3 × 10 4 (range of: 0.4–2.4) protozoa/ml of rumen contents.

Figures

FIGURE 1. Diploplastron ciliates recorded in Brazilian domestic sheep (Ovis aries L.). a – f. Diploplastron dehorityi sp. nov. a. Schematic drawing based on specimen stained with Lugol’s solution. b. Schematic drawing of the oral infraciliary bands pattern. c – d. Schematic drawing of variations in the morphology of skeletal plates. e. Specimen stained with Lugol’s solution. f. Specimen impregnated with silver carbonate. g – j. Diploplastron affine (Dogiel and Fedorowa, 1925). g. Schematic drawing based on specimen stained with Lugol’s solution. h. Schematic drawing of the oral infraciliary bands pattern. i. Specimen stained with Lugol’s solution. j. Specimen impregnated with silver carbonate. e – j. ACZ: adoral ciliary zone; AP: adoral polybrachykinety; CV: contractile vacuole; DCZ: dorsal ciliary zone; DP: dorsal polybrachykinety; Ma: macronucleus; Mi: micronucleus; Sk: skeletal plate; VP: vestibular polybrachykinety. Bars (e, f, i, j): 20 µm.