First record of Kelleridae in Brazilian waters. A geographical range expansion and a new Kelleria (Gurney, 1927) morphotype

This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Kelleridae is a copepod family found in all continents, mainly in tropical latitudes (Oomoto and Ueda, 2016) and is composed by 21 valid species, all in the genus Kelleria (Walter and Boxshall, 2021). It has a coastal epibenthic habit, with occasional presence in the plankton (Gurney, 1927; Gómez, 2006; Oomoto and Ueda, 2016; Walter and Boxshall, 2021). Oomoto and Ueda (2016, p. 47) noted that “Most species are probably endemic to their type localities. [...] about half of these species are described together with other congeners from the same sampling site or region”. Açu and Iquipari lagoons (40°59’00”W; 21°55’04”S and 41°01’27”W; 21°44’17”S respectively), sampled in this study, are located in the São João da Barra district, northern coast of the Rio de Janeiro State, Brazil. They have a narrow sand bar from the sea, which does not prevent the salinity to intrude its continental waters and Açu can become hypersaline during the dry season (Chagas and Suzuki, 2005; Rocha et al., 2019). Both lagoons are shallow (less than 1.5 m) with sandy sediment and seasonal benthic macroalgae near the sand bar and aquatic macrophytes on the inner area (Suzuki et al., 2002; Chagas and Suzuki, 2005; Monteiro and Gomes-Junior, 2005). Samples were taken 330 and 1,500 meters away from shore at the Açu lagoon and 150 meters at the Iquipari lagoon by filtering 200L of surface water with a graduated bucket through a 60μm mesh plankton net and preserved in 4% buffered formalin. Aliquots were analyzed using stereoscopic and optical microscopes until efficiency rate of 0.8 (Pappas and Stoermer, 1996; Cardoso and Marques, 2004) was achieved. Stacks of images at different focal distances, produced by a digital camera attached to a Biofocus Blue-1000 B-I-L-BI optical microscope, were assembled using Adobe Photoshop® and used as templates in Adobe Illustrator® to create vector graphic illustrations. Results showed the first record of Kelleridae in Brazil. General view and taxonomic features of the collected specimens are shown in Figure 1. We found two different species of Kelleria. One is identified to Kelleria reducta (Gómez, 2006) and the other has some unique morphological features, indicating the possibility of an undescribed Kelleria species. Our first record of Kelleria reducta in Brazil was at the Açu lagoon in November of 2016 (39.0 salinity), and the other Kelleria species (Kelleria sp.1) was first registered at Iquipari lagoon, in January 2017 (2.4 salinity) (Table 1). Since then, K. reducta was found again in April and October of 2019 and March of 2021 at the Açu lagoon and Kelleria sp.1 in February of 2020, also at the Açu lagoon, indicating a stable and reproductively viable population in the region with the presence of juvenile forms. Kelleria reducta was described on an estuarine system at Sinaloa, Mexico (Gómez, 2006) as the first Kelleria species found in the American continent. After that, K. reducta was found in 2012 at a coastal lagoon and in the littoral zone in Colombia (Suárez-Morales and Fuentes-Reinés, 2015; Fuentes-Reinés and Suárez-Morales, 2017). Female specimens of Kelleria reducta found in our study have two mediobasal teeth of mandibular blade, which are much larger than the others (Figure 1B), and maxillipedal basis with one long distal and on shorter proximal spines (Figure 1C), which are the main diagnostic characters for the species (Gómez, 2006). Regarding the caudal rami length/width ratio, our individuals have about 2.0 (Figure 1A), same as the Colombian specimen (Suárez-Morales and Fuentes-Reinés, 2015), while Gómez (2006) described a 3.0 ratio. The body size ranged from1.00 to 1.05 mm (n = 5), which is within the range found by Gómez (2006). Leg 5 has a serrate margin (Figure 1D), which is also a characteristic feature of the species. Specimens of Kelleria sp.1 is similar to K. regalis (Gurney, 1927) by having a bifid proximal spine on the second segment of the maxilliped and a pointed medial process at the first segment (Gurney, 1927) (Figure 1F). However, our individuals also have distinct features from what was described in Gurney (1927) and in Humes and Ho (1969) (Table 2) such as: 1) shorter body length (0.9 mm) [between 1.25 and 1.45 mm in K. regalis]; 2) prosome shape in dorsal view (Figure 1E) [wider then K. regalis]; 3) relative size of distal spines on the maxilla (Figure 1F); 4) 15 spinules on the maxilla proximal spine (Figure 1G) [12 spinules in K. regalis] and 5) serrate margin around leg 5 (Figure 1H) [absent in K. regalis]. Kelleria is considered epibenthic and their abundance in the plankton would greatly depend on water turbulence and life history of the species. We found over 11% relative abundance of the genus among the zooplankton community First record of Kelleridae in Brazilian waters. A geographical range expansion and a new Kelleria (Gurney, 1927) morphotype

Kelleridae is a copepod family found in all continents, mainly in tropical latitudes (Oomoto and Ueda, 2016) and is composed by 21 valid species, all in the genus Kelleria (Walter and Boxshall, 2021). It has a coastal epibenthic habit, with occasional presence in the plankton (Gurney, 1927;Gómez, 2006;Oomoto and Ueda, 2016;Walter and Boxshall, 2021). Oomoto and Ueda (2016, p. 47) noted that "Most species are probably endemic to their type localities.
[…] about half of these species are described together with other congeners from the same sampling site or region".
Açu and Iquipari lagoons (40°59'00"W; 21°55'04"S and 41°01'27"W; 21°44'17"S respectively), sampled in this study, are located in the São João da Barra district, northern coast of the Rio de Janeiro State, Brazil. They have a narrow sand bar from the sea, which does not prevent the salinity to intrude its continental waters and Açu can become hypersaline during the dry season (Chagas and Suzuki, 2005;Rocha et al., 2019). Both lagoons are shallow (less than 1.5 m) with sandy sediment and seasonal benthic macroalgae near the sand bar and aquatic macrophytes on the inner area (Suzuki et al., 2002;Chagas and Suzuki, 2005;Monteiro and Gomes-Junior, 2005).
Samples were taken 330 and 1,500 meters away from shore at the Açu lagoon and 150 meters at the Iquipari lagoon by filtering 200L of surface water with a graduated bucket through a 60µm mesh plankton net and preserved in 4% buffered formalin. Aliquots were analyzed using stereoscopic and optical microscopes until efficiency rate of 0.8 (Pappas and Stoermer, 1996;Cardoso and Marques, 2004) was achieved. Stacks of images at different focal distances, produced by a digital camera attached to a Biofocus Blue-1000 B-I-L-BI optical microscope, were assembled using Adobe Photoshop® and used as templates in Adobe Illustrator® to create vector graphic illustrations.
Results showed the first record of Kelleridae in Brazil. General view and taxonomic features of the collected specimens are shown in Figure 1. We found two different species of Kelleria. One is identified to Kelleria reducta (Gómez, 2006) and the other has some unique morphological features, indicating the possibility of an undescribed Kelleria species.
Our first record of Kelleria reducta in Brazil was at the Açu lagoon in November of 2016 (39.0 salinity), and the other Kelleria species (Kelleria sp.1) was first registered at Iquipari lagoon, in January 2017 (2.4 salinity) ( Table 1). Since then, K. reducta was found again in April and October of 2019 and March of 2021 at the Açu lagoon and Kelleria sp.1 in February of 2020, also at the Açu lagoon, indicating a stable and reproductively viable population in the region with the presence of juvenile forms.
Kelleria reducta was described on an estuarine system at Sinaloa, Mexico (Gómez, 2006) as the first Kelleria species found in the American continent. After that, K. reducta was found in 2012 at a coastal lagoon and in the littoral zone in Colombia (Suárez-Morales and Fuentes-Reinés, 2015; Fuentes-Reinés and Suárez-Morales, 2017).
Female specimens of Kelleria reducta found in our study have two mediobasal teeth of mandibular blade, which are much larger than the others ( Figure 1B), and maxillipedal basis with one long distal and on shorter proximal spines ( Figure 1C), which are the main diagnostic characters for the species (Gómez, 2006). Regarding the caudal rami length/width ratio, our individuals have about 2.0 ( Figure 1A), same as the Colombian specimen (Suárez-Morales and Fuentes-Reinés, 2015), while Gómez (2006) described a 3.0 ratio. The body size ranged from1.00 to 1.05 mm (n = 5), which is within the range found by Gómez (2006). Leg 5 has a serrate margin ( Figure 1D), which is also a characteristic feature of the species.
Specimens of Kelleria sp.1 is similar to K. regalis (Gurney, 1927) by having a bifid proximal spine on the second segment of the maxilliped and a pointed medial process at the first segment (Gurney, 1927) ( Figure 1F). However, our individuals also have distinct features from what was described in Gurney (1927) and in Humes and Ho (1969) ( Table 2)  Kelleria is considered epibenthic and their abundance in the plankton would greatly depend on water turbulence and life history of the species. We found over 11% relative abundance of the genus among the zooplankton community Copepoda, as is well known since its first occurrence in the American continent (Gómez, 2006). The present paper expands K. reducta southern range distribution from Colombia to Brazil which appears to be an endemic species from the American continent, as well at the Açu lagoon in December of 2017, suggesting a planktonic life stage for copepodite. Because we repeatedly found juvenile forms of Kelleria at both lagoons, it is likely that populations of both species are well established in the region, reinforcing Kelleria as a widespread genus of  as Kelleria sp.1, yet to be fully described, that appears to be endemic to Brazil. This pattern and the occurrence of two congener species of Kelleria in the same region reinforces Oomoto and Ueda (2016) statement, as quoted above.