Mastobranchus braziliensis, Silva & Amaral, 2022

Silva, Camila Fernanda Da & Amaral, Antonia Cecilia Zacagnini, 2022, Capitellidae (Annelida) from the Brazilian Continental Margin (SW Atlantic): new occurrences of three genera and description of new species, Zootaxa 5104 (1), pp. 89-110 : 95-98

publication ID

https://doi.org/10.11646/zootaxa.5104.1.5

publication LSID

lsid:zoobank.org:pub:9FEFDF3D-A6AB-45FD-9BC7-72E3DE8E3E8C

DOI

https://doi.org/10.5281/zenodo.6316700

persistent identifier

https://treatment.plazi.org/id/EB6FBB29-D9B8-473F-B25C-25AFD4FE23CC

taxon LSID

lsid:zoobank.org:act:EB6FBB29-D9B8-473F-B25C-25AFD4FE23CC

treatment provided by

Plazi

scientific name

Mastobranchus braziliensis
status

sp. nov.

Mastobranchus braziliensis sp. nov.

( Fig. 3A–J View FIGURE 3 ; Table 1 View TABLE 1 )

http://zoobank.org/ EB6FBB29-D9B8-473F-B25C-25AFD4FE23CC

Material examined. Campos Basin: Holotype ( ZUEC POL 20222 View Materials ) 21°42'37''S 40°8'59''W, 09 Mar 2009, subtidal, 147m, Stn. HAB13/H5, 1 spec. GoogleMaps Paratype 1 ( ZUEC POL 20223 View Materials ) 22°17'42''S 40°27'00''W, 04 Jul 2009, subtidal, 103m, Stn. HAB16/E4, 1 spec. GoogleMaps Paratype 2 ( ZUEC POL 20215 View Materials ) 21°28'21''S 40°48'34''W, 20 Jul 2009, subtidal, 22m, Stn. HAB17/ FOZ13, 1 spec. GoogleMaps Paratype 3 ( ZUEC POL 20211 View Materials ) 21°34'12''S 40°25'29''W, 23 Jul 2009, subtidal, 28m, Stn. HAB17/FOZ30, 1 spec. GoogleMaps Espírito Santo Basin : Paratype 4 ( ZUEC POL 20203 View Materials ) 19°35'2''S 39°38'40"W, 18 Jul 2011, subtidal, 30m, Stn. AMB2/FOZ10, 1 spec. GoogleMaps Paratype 5 ( ZUEC POL 20202 View Materials ) 18°40'56''S 38°55'41"W, 17 Jul 2013, subtidal, 44m, Stn. AMB13/G3, 1 spec. GoogleMaps Paratypes 6 and 7 ( ZUEC POL 20200 View Materials ) 18°53'31''S 39°6'20"W, 02 Feb 2012, subtidal, 43m, Stn. AMB7/F3, 2 specs GoogleMaps . Paratypes 8–12 ( ZUEC POL 20220 View Materials ) 18°53'30''S 39°6'21"W, 02 Feb 2012, subtidal, 43m, Stn. AMB7/F3, 5 specs GoogleMaps . Paratype 13 ( ZUEC POL 20193 View Materials ) 18°53'30''S 39°6'21"W, 02 Feb 2012, subtidal, 34m, Stn. AMB7/F2, 1 spec. GoogleMaps Paratype 14 ( ZUEC POL 20205 View Materials ) 18°40'54''S 38°55'42"W, 17 Jul 2013, subtidal, 28m, Stn. AMB13/G2, 1 spec. GoogleMaps Paratype 15 ( ZUEC POL 20801 View Materials ) 21°33'52''S 40°42'53''W, 10 Mar 2009, subtidal, 22m, Stn. HAB13/FOZ18, 1 spec. GoogleMaps

Additional material examined. Campos Basin: ( ZUEC POL 20210 View Materials ) 22°39'11''S 40°48'49''W, 11 Mar 2009, subtidal, 22m, Stn. HAB13/FOZ12, 1 spec. ( ZUEC POL 20212 View Materials ) GoogleMaps 21°33'52''S 40°42'53''W, 10 Mar 2009, subtidal, 22m, Stn. HAB13/FOZ13, 2 specs. ( ZUEC POL 20214 View Materials ) GoogleMaps 21°33'52''S 40°42'53''W, 10 Mar 2009, subtidal, 22m, Stn. HAB13/FOZ18, 6 specs. ( ZUEC POL 20216 View Materials ) GoogleMaps 21°33'52''S 40°42'53''W, 10 Mar 2009, subtidal, 22m, Stn. HAB13/FOZ13, 1 spec. ( ZUEC POL 20217 View Materials ) GoogleMaps 21°39'31''S 40°31'25''W, 13 Mar 2009, subtidal, 28m, Stn. HAB13/ FOZ25, 1 spec. ( ZUEC POL 20219 View Materials ) GoogleMaps 22°12'31''S 40°14'7''W, 24 Jul 2009, subtidal, 97m, Stn. HAB17/FOZ43, 1 spec. ( ZUEC POL 20225 View Materials ) GoogleMaps 21°44'39''S 40°43'8''W, 19 Jul 2009, subtidal, 21m, Stn. HAB17/FOZ19, 1 spec. ( ZUEC POL 20226 View Materials ) GoogleMaps 21°39'32''S 40°31'24''W, 23 Jul 2009, subtidal, 28m, Stn. HAB17/FOZ25, 1 spec. ( ZUEC POL 20227 View Materials ) GoogleMaps 21°24'45''S 40°25'17''W, 20 Jul 2009, subtidal, 32m, Stn. HAB17/FOZ29, 1 spec. Espírito Santo Basin : ( ZUEC POL 20195 View Materials ) 18°53'30''S 39°6'21"W, 17 Jul 2013, subtidal, 43m, Stn. AMB14/F3, 1 spec. ( ZUEC POL 20196 View Materials ) GoogleMaps 18°53'30''S 39°6'21"W, 18 Jul 2011, subtidal, 26m, Stn. AMB2/FOZ9, 1 spec. ( ZUEC POL 20197 View Materials ) GoogleMaps 19°47'22''S 39°43'19"W, 19 Dec 2010, subtidal, 37m, Stn. AMB1/FOZ13, 1 spec. ( ZUEC POL 20198 View Materials ) GoogleMaps 20°1'2''S 39°50'18"W, 18 Jul 2011, subtidal, 49m, Stn. AMB2/FOZ16, 1 spec. ( ZUEC POL 20199 View Materials ) GoogleMaps 19°09'48''S 39°29'20"W, 02 Feb 2012, subtidal, 20m, Stn. AMB7/E1, 2 specs. ( ZUEC POL 20204 View Materials ) GoogleMaps 18°40'54''S 38°55'42"W, 02 Feb 2012, subtidal, 44m, Stn. AMB7/G3, 1 spec. ( ZUEC POL 20206 View Materials ) GoogleMaps 18°40'54''S 38°55'42"W, 17 Jul 2013, subtidal, 44m, Stn. AMB13/G3, 1 spec. ( ZUEC POL 20207 View Materials ) GoogleMaps 20°34'33''S 40°20'52"W, 17 Jul 2013, subtidal, 21m, Stn. AMB14/B1, 1 spec. ( ZUEC POL 20208 View Materials ) GoogleMaps 18°40'54''S 38°55'42"W, 02 Feb 2012, subtidal, 44m, Stn. AMB7/G3, 1 spec.

Comparative material examined. Holotype Mastobranchus loii Gallardo, 1968 ( LACM-AHF POLY 317 ), 12°13'24''N 109°14'13''E, 14m, 11 Jan 1960, Bay of Nha-Trang , South Vietnam, North Pacific. Holotype Mastobranchus variabilis Ewing, 1984 ( USNM 81993 View Materials ) GoogleMaps and paratype 1 ( USNM 81994 View Materials ), 27°36'29''N 82°55'48''W, Jun 1980, Tampa Bay , Gulf of Mexico , North Atlantic Ocean ; GoogleMaps and paratype 2 ( LACM-AHF POLY 1369 ), 314°06'30''N 114°28'15''W, Feb 1980, Gulf of Mexico, North Atlantic Ocean.

Description. Incomplete holotype 17 mm long, 1.1 and 0.9 mm wide (anterior and posterior thoracic region, respectively) for 28 chaetigers. Body rounded; anterior thorax 1.5x wider than posterior thorax; posterior thorax almost of same width as abdomen. Yellowish color in alcohol.

Prostomium triangular, small, 1/3 of peristomium width; small palpode, 1/2 of prostomium length. Light brown stain on dorso-lateral prostomium may be eyespots. Peristomium 2x wider than long and 1.5x longer than the first thoracic chaetiger. Nuchal organs not everted.

Thorax with 11 chaetigers.Chaetiger 1 uniramous. Capillaries on notopodia of chaetigers 1–11 and on neuropodia of chaetigers 2–11. Chaetigers 1–4 wider and more inflated than remaining ones, with a shallow lateral groove, faintly tessellated, with shallow intersegmental division ( Fig. 3A–B, D View FIGURE 3 ). Chaetigers 5–11 square-like, straight, 1.1x wider than long, strongly biannulated, with deep intra- and intersegmental grooves, and with mid-lateral lobes (MLL) ( Fig. 3B View FIGURE 3 ). Right and left dorsal chaetal bundles widely separated on chaetiger 1 (dorso-lateral), distance reduced up to chaetiger 11 (dorsal). Dorsal and ventral bundles with 11 capillary chaetae. Thorax rounded ( Fig. 3B View FIGURE 3 ). Lateral organs very small, visible only after staining. A pair of genital pores between chaetigers 7/8, 8/9, 9/10, 10/11, and 11/12 ( Fig. 3B–C View FIGURE 3 ). Transition between thorax and abdomen subtle, marked by chaetal change, distance of chaetal bundles, and shape of chaetigers ( Fig. 3B, D View FIGURE 3 ).

All abdominal chaetigers with hooded hooks on neuropodia and mixed hooded hooks and capillaries on notopodia ( Fig. 3C View FIGURE 3 ). First six abdominal chaetigers rectangular (1.5x wider than long), following chaetigers square-like (as wide as long). Chaetae and hooded hooks emerge from last quarter of chaetiger, near division between chaetigers. Both notopodial bundles of hooded hooks (~12 each fascicle) and capillaries (~15 each fascicle) emerging dorsally, almost together ( Fig. 3C, F View FIGURE 3 ); neuropodial bundles of hooded hooks (~ 50 each fascicle) long, extending laterally and ventrally ( Fig. 3D View FIGURE 3 ). Dorso-lateral lateral organs throughout abdomen. Noto- and neuropodia with poorly developed lobes ( Fig. 3C–D View FIGURE 3 ). Notopodial hooded hooks with three rows of teeth (3–2–3) above main fang, large main fang and slightly curved; long shaft and hood, without node ( Fig. 3G–H View FIGURE 3 ). Neuropodial hooded hooks with three rows of teeth (3–2–3) above main fang, large main fang and slightly curved; short shaft and hood, with node ( Fig. 3I–J View FIGURE 3 ).

One complete specimen (paratype 15) with retractile branchiae after chaetiger 70; dorsal, bifurcated branchiae, posterior to notopodial lobe ( Fig. 3E View FIGURE 3 ); and with mixed hooded hooks and capillaries on abdominal notopodia up to chaetiger 56. Pygidium bearing a long ring after last chaetiger and four small cirri (3x longer than wide), forming a circular arrangement on the dorsal region; large anal aperture ventrally ( Fig. 3E View FIGURE 3 ).

Variation. Specimens ranging from 3.7–38 mm long, 0.25–1.2 mm wide for 27–100 chaetigers. Juveniles (<0.6 mm wide) present hooded hooks on the last 3–4 thoracic neuropodia, transition between thorax and abdomen not distinguishable, mixed hooded hooks and capillaries throughout abdominal notopodia, and lack areolation and lateral groove on anterior thorax.

Methyl Green staining pattern (MGSP). Thorax with intersegmental division staining very dark. Abdomen with a dark stain zone around noto- and neuropodial lobes ( Fig. 3F View FIGURE 3 ). Dorsal region of abdomen staining darker than ventral. Ventral region of abdomen with a dark median line throughout ( Fig. 3F View FIGURE 3 ).

Remarks. Mastobranchus braziliensis sp. nov. is characterized by having thoracic chaetigers 1–4 wider and more inflated than the remaining ones, with a shallow lateral groove, and faintly tessellated; dorsal, bifurcated branchiae on posterior abdomen; and mixed capillaries and hooded hooks on notopodia of almost all abdominal chaetigers. Mixed capillaries and hooded hooks on notopodia of abdominal chaetigers is one of the most noticeable characteristic of the genus Mastobranchus , but the number of chaetiger bearing capillaries and hooded hooks varies among known species, and Mastobranchus braziliensis sp. nov. presents the highest number of chaetigers with mixed chaetae. M. braziliensis sp. nov. also differs from the known species by the morphology of branchiae, which is bifurcated, in contrast with species with multifilament branchiae ( M. trinchesii , five; M. loii , 3–7; M. variabilis , 5–8; M. uru , 3–8). The number of teeth above the main fang in hooded hooks is also a useful character to differentiate Mastobranchus species. Although some species were poorly described lacking photographs, it is possible to affirm that Mastobranchus is a very homogeneous and well-defined genus. Except for the first chaetigers, which can be uniramous or biramous ( M. trinchesii ), all species seem to share specific characteristics, such as presence of a palpode, faintly tessellated thoracic epithelium, notopodial bundles of abdomen emerging dorsally, very close to each other, a long line of neuropodial hooks, notopodial hooks longer and straighter (without node) than neuropodial hooks, post-notopodial branchiae, pygidium with four cirri, and Methyl Green staining pattern distinct ( M. braziliensis sp. nov., M. loii , and M. uru ).

Etymology. This species was named after its locality, since it is the first species of the genus recorded to Brazil.

Habitat. Shallow subtidal regions (20–147m), in soft-bottoms.

Type locality. Campos Basin , Southwest Atlantic Ocean (21°42'37''S 40°8'59''W) GoogleMaps .

Distribution. Southwest Atlantic Ocean, Campos and Espírito Santo Basins ( Brazil).

ZUEC

Museu de Zoologia da Universidade Estadual de Campinas