Brachionus paranguensis, Guerrero-Jimenez, Gerardo, Vannucchi, Patrizia Elena, Silva-Briano, Marcelo, Adabache-Ortiz, Araceli, Rico-Martinez, Roberto, Roberts, David, Neilson, Roy & Elias-Gutierrez, Manuel, 2019

Guerrero-Jimenez, Gerardo, Vannucchi, Patrizia Elena, Silva-Briano, Marcelo, Adabache-Ortiz, Araceli, Rico-Martinez, Roberto, Roberts, David, Neilson, Roy & Elias-Gutierrez, Manuel, 2019, Brachionus paranguensis sp. nov. (Rotifera, Monogononta), a member of the L group of the Brachionus plicatilis complex, ZooKeys 880, pp. 1-23 : 1

publication ID	https://dx.doi.org/10.3897/zookeys.880.28992
publication LSID	lsid:zoobank.org:pub:40B9F4C2-AAE4-4E6B-947D-945C8CF52A7D
persistent identifier	https://treatment.plazi.org/id/6560750D-1719-5E1F-B5E5-8FC2202E1B63
treatment provided by	ZooKeys by Pensoft
scientific name	Brachionus paranguensis
status	sp. nov.

Treatment

Brachionus paranguensis sp. nov. Figs 4 A–H View Figure 4 , 5 A–C View Figure 5 , 6 A–F View Figure 6

Type locality.

The volcano Rincón de Parangueo, Guanajuato, Mexico, has two or three water bodies inside the crater, depending on the season, and B. paranguensis sp. nov. was present in one of them, 20°25'46"N; 101°14'48"W, at the altitude of 1686 m above sea level ( Fig. 3 View Figure 3 ).

Material examined.

In order to confirm the identity of B. paranguensis sp. nov., hundreds of individuals from field and culture samples representing all stages (amictic females, males, resting eggs, parthenogenetic eggs, and unfertilized sexual eggs), and around 30 trophi, were examined by LM and SEM. Specifically, hundreds of females were used to take morphometric measurements, and dozens of males were observed to analyze their morphological features. Moreover, diapausing eggs, parthenogenetic eggs and unfertilized eggs were examined and pictures of each egg were taken. Finally, approximately 30 trophi were analyzed in order to compare their morphological features with those of the other eggs belonging to the L group.

Holotype. A parthenogenetic female mounted on a slide with a mix of formaldehyde-glycerol sealed with DePex medium, deposited in the Zooplankton Reference Collection of El Colegio de la Frontera Sur with accession number ECO-CH-Z-10331. Paratypes. Two slides with a parthenogenetic female, deposited in the Zooplankton Reference Collection of El Colegio de la Frontera Sur with accession numbers ECO-CH-Z-10332, 10333.

Differential diagnosis.

Parthenogenetic female: No clear morphological differences were observed between B. paranguensis sp. nov. and the other species belonging to the L group of the B. plicatilis complex with respect to the anterior dorsal spine, the U-shape sinus, the orange peel like surface of the lorica, and the presence of gastric glands. An exception is B. asplanchnoidis , whose lorica presents an elongated and wider shape, and the antero-ventral U-shape sinus is wider compared to that of the other members.

Trophi: In B. paranguensis sp. nov. satellites are robust and there are sharp projections in the inner upper margin; basifenestras with similar size and shape, ramus with two posterior projections, the left one smaller and thinner than the right one. In B. plicatilis s.s. the shape of the satellites is triangular with no projection; ramus with two posterior projections, the left one bigger and wider than the right one; basifenestras asymmetrical with different sizes. In B. manjavacas the shape of the satellites is triangular and sharper compared to B. plicatilis s.s.; ramus with two posterior projections, the left one bigger and wider than the right one; basifenestras with same shape but different size, the left one bigger than the right one. In B. asplanchnoidis satellites are robust and the projections in the inner upper margin is rounded; ramus with two posterior projections, the left one smaller and thinner than the right one, the right one with cylindrical shape; basifenestras with different shape and size, the left one smaller than the right one.

Resting eggs: Oval shape in B. paranguensis sp. nov., B. plicatilis s.s. and B. manjavacas , although the two latter species also present small holes on the surface of the eggs ( Ciros-Pérez et al. 2001; Guerrero-Jiménez et al. in prep.).

Ecology: B. paranguensis sp. nov. grows preferentially in salinities higher than 25 g L-1. B. plicatilis s.s. grows better in salinities from 5 to 15 g L-1 ( Yin and Zhao 2008), while B. manjavacas is usually cultured in a salinity of 12 g L-1. Finally, B. asplanchnoidis can be observed in salinities from 8 to 44 g L-1, although Michaloudi et al. (2017) for their study cultured the species in a salinity of 16 g L-1.

Description.

The population of B. paranguensis sp. nov. from Rincón de Parangueo volcano was used to formally describe all individuals belonging to the L4 group of the B. plicatilis complex. Parthenogenetic females ( Fig. 4F, G View Figure 4 ) had a soft lorica with an orange peel like surface ( Fig. 4C View Figure 4 ), two gastric glands (gg) (see arrows, Fig. 4A View Figure 4 ) and two lateral antennae (LA) in the middle of the body (see arrows, Fig. 4A, E View Figure 4 ). Anterior dorsal margin with six spines, three on each side of a U-shape sinus like the other members of the L group. All spines are triangular ( Fig. 4A, B View Figure 4 ). Anterior ventral margin with bilateral symmetry, four well-defined lobes with a medial sinus, both internal lobes were more pronounced than the external lobes ( Fig. 4A, B View Figure 4 ). Foot aperture well defined ( Fig. 4D View Figure 4 ). Adult females had a length of 216.97 ± SD 13.78 μm (N = 20), width 159.93 ± SD 10.93 μm (N = 20), and 126.21 ± SD 7.7 μm of head aperture, dorsal view (N = 20), see Table 3 View Table .

Male ( Fig. 4H View Figure 4 ): Twenty individuals were analyzed. Anterior ventral margin had two lobes with a medial sinus and five to six pellets, the life cycle without food was of four days and its length was 78.48 ± SD 2.8 μm and width 72.7 ± SD 2.3 μm.

Egg types: The outer membrane of the resting eggs presented a slightly rough ornamentation ( Fig. 5A View Figure 5 .a, A.b) and the length was 112.6 ± SD 4.8 μm and 91.2 ± SD 4.7 μm width (N = 7), see Figure 5A View Figure 5 . The parthenogenetic eggs had a smooth surface and was 127.4 ± 9.5 long and 110.7 ± SD 6.1 μm wide (N = 9), see Figure 5B View Figure 5 . Finally, the unfertilized sexual eggs that produced males were 73.03 ± SD 3.2 μm long and 59.8 ± SD 2.18 μm wide (N = 9), see Figure 5C View Figure 5 .

Trophi: Malleate type with all the characters of the genus ( Fig. 6A, B View Figure 6 ). Manubria were triangular in shape with sharp claw-shaped tips at their distal end ( Fig. 6D View Figure 6 ). The junction that holds the manubrium with the uncus was wide in both dorsal and ventral view ( Fig. 6A, B View Figure 6 ). Unci presented four teeth decreasing in size from the ventral one and the subuncus is present underneath each tooth ( Fig. 6F View Figure 6 ). The membrane that joins the uncus with the satellites was thick and the protrusion that innervates them was also clearly denoted on the back of the uncus (see Fig. 6A View Figure 6 ). The satellites were robust, irregularly shaped but arranged symmetrically, also sharp projections were observed on the anterior section of the satellites with the tip pointing inwards towards the central axis of the trophi ( Fig. 6E View Figure 6 ). Ramus asymmetrical with two posterior projections, the left one smaller and thinner than the right one and basifenestras with similar shape and size ( Fig. 6C View Figure 6 ). Fulcrum short, with triangular shape ( Fig. 6C View Figure 6 , see arrow and F).

Etymology.

The specific name refers to the type locality, the volcanic maar Rincón de Parangueo.

Distribution-habitat.

According to the DNA sequences available in NCBI, B. paranguensis sp. nov. individuals were reported in Mexico, USA, Chile, Europe, Australia, and Japan. The habitat of B. paranguensis n. sp is represented by high salinity environments (>25 g L-1). Physical and chemical parameters of the maar where specimens were collected: Temperature= 28 °C; Conductivity= 43.2 mS/cm-1; Dissolved Oxygen = 5.5 mg L-1; pH= 11.07.

Ecology.

Under laboratory conditions (25 °C, 25 g L-1 salinity, 106 cells/ml of Nannochloropsis oculata provided as food) amictic females had a maximum lifespan of 10.8 days. Eggs per rotifer were 15.4 ± SD 5.8, and the maximum intrinsic growth rate was 0.49 (N = 10).