Corresponding author: Juliana Lopes Segadilha (
Academic editor: Sammy De Grave
Based on specimens collected from eulittoral zone in rocky shores of northeast of Rio de Janeiro (Brazil) on 2017, two new tanaidaceans species from two different suborders are described:
Current knowledge about the crustacean order
Among coastal environments, rocky shores stand out for the high biodiversity of macroalgae, invertebrates, fish and seabirds, in addition to great ecological and economic importance (
The present study is part of the Project Rocky Shores: ecology, impacts, and conservation in the areas of Região dos Lagos and the north Fluminense, which aims to survey biodiversity, study the abundance and structure of invertebrate macrofauna communities and their correlations with environmental parameters in rocky shores of the northern part of Rio de Janeiro (Macaé, Rio das Ostras and Armação dos Búzios).
The Project Rocky Shores: ecology, impacts, and conservation in the areas of Região dos Lagos and the north Fluminense has been executed by the Institute of Biodiversity and Sustainability
Sampling was carried out at four stations: Areias Negras Beach (
At each site, collections were made from three zonation strata of the eulittoral zone: upper (A), intermediate (B) and lower (C). The strata were defined according to the dominant group of organisms covering each stratum, being: Upper = green macroalgae (
Five replicates were taken in each stratum, along 30 meters of extension on each shore. Sampling was made during low tides (≤ 0.2 m). The area of each sampled unit was delimited by a quadrat of 20x20 cm (0.04 m²) and samples were scraped with spatulas.
Specimens were sorted at the Laboratório Integrado de Biologia de Vertebrados, located in
Drawings were made using a microscope Zeiss with a camera lucida and digitalized with WACOM Tablet using the program Adobe Illustrator CC 2017. The appendages were dissected using chemically sharpened tungsten-wire needles. Body length was measured from the tip of the rostrum to the tip of the pleotelson, and pereonite width at the broadest part. The length/width ratio was calculated from the measurements made in the middle length and width of an article. The measurements of cheliped articles and the morphological terminology follow that used by
All material cited herein (
Four species of
See
Family
The species
The genus
Holotype: Brazil • 1 ♀ ovigerous, TL 2.4 mm (
Allotype: Brazil • 1 ♂, TL 1.8 mm (
Paratypes: Brazil • 1 ♀ ovigerous and 1 ♂, dissected, TL 2.0 mm (
Female. Rostrum with rounded tubercles at base and bifurcate tip. Pleonites 2 and 5 with pleura having long distal seta. Antennule article-1 inner margin with one blunt apophysis, outer flagellum with three segments. Mandible palp article-2 and article-3 with six and nine finely penicillate setae on inner margin respectively. Maxilliped palp article-1 outer margin with seta. Pereopod-1 basis with dorso-proximal margin lacking blunt, spiniform process; carpus and propodus with two and four ventral spines, respectively. Pereopods 1–2 basis with several setae along ventral margin. Pleopods biramous, exopod and endopod each with one long penicillate seta. Uropod exopod shorter than endopod segments 1–2 combined, endopod with four segments.
Male. Cheliped propodus just wider than long, ventral margin with only three simple setae (without proximal apophysis).
Based on ovigerous ♀ holotype (
Body (Figs
Digital image of
Cephalothorax (Fig.
Pereon (Fig.
Pleon (Figs
Pleotelson (Figs
Antennule (Fig.
Antenna (Fig.
Mouthparts: Labrum not recovered. Mandibles (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
Cheliped (Fig.
Pereopod-1 (Fig.
Pereopod-2 (Fig.
Pereopod-3 (Fig.
Pereopod-4 (Fig.
Pereopod-5 (Fig.
Pereopod-6 (Fig.
Pleopods (Fig.
Uropod (Fig.
Cheliped (Fig.
The name is dedicated to Brazil, the country where the species were collected.
Eulittoral zone of rocky shores at Santana Archipelago, Macaé, Rio de Janeiro, Brazil.
This species was found exclusively at eulittoral zone on rocky shores (macroalgae bank) of Santana Archipelago, Macaé, Rio de Janeiro, Brazil, Southwestern Atlantic (Fig.
In total, 33 specimens of
The new species from Brazil is more similar to those
The new species from Brazil closely resembles
1 | Pereopod-1 basis dorso-proximal margin with blunt, spiniform process | |
– | Pereopod-1 basis dorso-proximal margin lacking blunt, spiniform process | 2 |
2 | Pleonites 1–5 without a long seta on dorsolateral margins | |
– | At least the last pleonite with a long seta on dorsolateral margins | 3 |
3 | Pleopods absent | |
– | Pleopods present (uni- or biramous) | 4 |
4 | Only the last pleonite with a long seta on distolateral margins | 5 |
– | More than the last pleonite with a long seta on distolateral margins | 6 |
5 | Antennule first peduncular article with some dentiform processes on the proximal half of inner margin | |
– | Antennule first peduncular article without dentiform processes on the proximal half of inner margin | |
6 | Last four pleonites with a long seta on distolateral margins | 7 |
– | At most the last three pleonites with a long seta on distolateral margins | 8 |
7 | Pleopods biramous, with biarticulate exopodite | |
– | Pleopods biramous, with uniarticulate exopodite (in male), or uniramous (in female) | |
8 | Last three pleonites with a long seta on lateral margins | |
– | Only two pleonites (second and fifth) with a long seta on distolateral margins | 9 |
9 | Pleopods uniramous | |
– | Pleopods biramous | 10 |
10 | Pereopod-1 carpus and propodus with three and five ventral spines (= spiniform setae), respectively; one rami of pleopods with two long setae | |
– | Pereopod-1 carpus and propodus with two and four ventral spines (= spiniform setae), respectively; each rami of pleopods with one long setae | 11 |
11 | Antennule main flagellum with four short, thick segments. Mandible palp article-2 with three penicillate (= setulate) setae on inner margin. Maxilliped palp article-1 outer margin with very small seta. Pereopod-2 ventral margin of propodus with three setae | |
– | Antennule main flagellum with three segments. Mandible palp article-2 with more than three penicillate (= setulate) setae on inner margin. Maxilliped palp article-1 outer margin with seta. Pereopods 2–3 propodus with four ventral spines (= spiniform setae) | 12 |
12 | Mandible palp article-2 and article-3 with five and eight finely penicillate (= setulate) setae on inner margin, respectively. Uropod exopod longer than endopod segments 1–2 combined. Uropod endopod with five segments | |
– | Mandible palp article-2 and article-3 with six and nine finely penicillate (= setulate) setae on inner margin, respectively. Uropod exopod shorter than endopod segments 1–2 combined. Uropod endopod with four segments |
Pleon consisting of five pleonites (all reduced) and pleotelson, provided with only one pair of greatly reduced pleopods. Antennule with subterminal aesthetasc. Antenna article-2 with two setae. Maxilliped endites with gustatory cusps on distal margin. Cheliped carpus with three ventral setae. Pereopods 2–3 propodus with two ventral setae. Uropods exopod one or two-articled; endopod two-articled.
The family
Holotype: Brazil • 1 ♀ non-ovigerous, TL 1.3 mm (
Allotype: Brazil • 1 ♂, TL 1.0 mm (
Paratypes: Brazil • 1 ♀ ovigerous (only oostegites remained), dissected TL 1.2 mm (
Female. Pereopods 1–3 coxa with long seta about half as long as basis. Pereopods 2–3 carpus with one ventrodistal seta. Pereopods 4–6 propodus with two spines and one seta ventrally. Uropod endopod article-2 0.8 times as long as article-1; exopod one-articled.
Based on non-ovigerous ♀ holotype (
Body (Figs
Digital image of
Cephalothorax (Figs
Pereonites 1–6 with length ratio of 0.6:0.8:0.9:1.0:1.0:0.6; pereonites 1, 2, 3 and 6 wider than long, pereonites 3–5 as long as wide; all pereonites with pair of long dorsodistal and short lateral simple setae; pereonite-1 with another pair of minute dorsodistal setae and pereonites 4–6 with pair of long mid-lateral setae.
Pleon (Figs
Pleotelson (Figs
Antennule (Figs
Antenna (Fig.
Mouthparts: Labrum (Fig.
Maxilliped (Fig.
Cheliped (Fig.
Pereopod-1 (Fig.
Pereopod-2 (Fig.
Pereopod-3 (Fig.
Pereopod-4 (Fig.
Pereopod-5 (Fig.
Pereopod-6 (Fig.
Pleopods (Fig.
Uropod (Fig.
Named in honor of Dr. Luciano Fischer (
Eulittoral zone of rocky shores at Areias Negras Beach, Rio das Ostras, Rio de Janeiro, Brazil.
This species was found within a macroalgae bank of the eulittoral zone of rocky shores at Areias Negras Beach, Rio das Ostras, Rio de Janeiro, Brazil, Southwestern Atlantic (Fig.
Geographic distribution of
A total of seven specimens were found in only two of 56
The genus
1 | Pereopods 1–3 coxa with short seta (less than half of basis). Pereopods 2–3 carpus with seta and spine ventrodistally. Pereopods 4–6 propodus with two setae ventrally. Uropod endopod article-2 small, about 0.4 times as long as article-1, and exopod two-articled | |
– | Pereopods 1–3 coxa with long seta (about half as long as basis). Pereopods 2–3 carpus with only seta ventrodistally. Pereopods 4–6 propodus with two spines and seta ventrally. Uropod endopod article-2 0.8 times as long as article-1 and exopod one-articled |
The apseudomorphs are predominantly a shallow-water group and the family
Currently, there are regions whose shallow-water tanaidacean faunas are still under-researched. A study of the
Apart from that, six from the 54 species registered in Brazilian coast were recorded in sediments with algae (
The diversity of the tanaidaceans in certain ocean regions remains to be discovered, especially in Brazil where this group is still understudied (in rocky intertidal sites, shallow water sediment or deep sea environments). Both new species represent also new records to Southwestern Atlantic for the family
Great advances have been made in the past twenty years to understand the Brazilian Tanaidacean fauna; however progress will continue to be restricted by the lack of tanaidacean taxonomists and researchers, but mainly by the lack of funding for this enterprise. Nevertheless, it is evident from our current knowledge that the
This research was carried out within the scope of the “Project Rocky Shores/