Scoloplos maranhensis, Oliveira & Cutrim & Vieira & Ferreira & Almeida & Nogueira Júnior, 2019

Oliveira, Veronica M., Cutrim, Allana S. T., Vieira, Anna Karen M., Ferreira, Camila N., Almeida, Zafira S. & Nogueira Júnior, Miodeli, 2019, Description of Scoloplos maranhensis sp. nov. (Orbiniidae, Annelida) from tropical Brazilian mangrove, Iheringia, Série Zoologia (e 2019009) 109, pp. 1-10 : 2-8

Scoloplos maranhensis sp. nov.

urn:lsid:zoobank.org:act:B2DA4CC4-26D5-483A-9CFC-44718328EA2F

( Figs 2-12 )

Type material. Holotype, Mangrove from Quebra Pote, São Luís, state of Maranhão, Brazil (02°41.344’S; 44°12.604’W), 09 January 2014 ( CIPY – 1730).

Paratypes. A total of 11 paratypes, length ranging for 1.4 to 0.2 mm and number of segments from 10 to 80. Quebra Pote mangrove, Brazil (02°41.344’S; 044°12.604’W): 05 November 2013, (1 paratype, CIPY - 1731); 07 January 2014; (2 paratypes, CIPY - 1732); 03 September 2014 (6 paratypes, CIPY 1733 ); 28 September 2012 (2 paratypes, CIPY 1734 ) .

Diagnosis. Thorax with 12 segments, chaetae appearing since the first segment. Notopodia and neuropodia without papillae. Conical branchiae from chaetiger 12 to the end of the body. Branchiae larger and more robust in the anterior segments. Each branchial pair located on median dorsal part. Cirriform post-chaetal notopodial lobes, inconspicuous at first, but long from chaetiger 3. Thoracic notopodia with seven crenulated capillary chaetae, neuropodia with two crenulated capillaries and six slender-smooth hooks. Abdominal notopodia with crenulated capillary and furcate chaetae and and neuropodia crenulated capillary chaetae.

Description. The holotype is a complete specimen with 57 segments, 3.0 mm length, 0.1 mm wide. Body long, very slender and tapered at the posterior end ( Fig. 2 ). Prostomium conical, longer than wide ( Fig. 3 ). Eyes, antennae and tentacular cirri absent, nuchal organs present but not visible ( Fig. 3 ). Peristomium as a single achaetous ring, similar in length to segment 1. Undivided smooth proboscis covered with diffusely distributed rounded small papillae ( Figs 3, 4 ). Thorax dorsoventrally flattened with 12 chaetigers, widest in the middle part. Slight transition from thorax to abdomen from segment 12. All parapodia birramous, present from the first chaetiger. Abdominal neuropodia rounded, notopodia with one dorsal lamella and all ventral lamella absent. Thoracic notopodia and neuropodia without papillae. Branchiae conical, on median-dorsal position, beginning from the 12 th segment and continuing through the body. Branchiae at first long and robust, becoming thinner towards the posterior end. Cirriform post-chaetal notopodial lobes inconspicuous at first, but long from chaetiger 3; neuropodia

Description of Scoloplos maranhensis sp. nov. ( Orbiniidae ,... OLIVEIRA et al.

rounded on thoracic chaetigers and with a developed lobe in abdominal chaetigers. Thoracic notopodia with crenulated capillaries ( Figs 5, 6 , 9, 10 ) and abdominal notopodia with crenulated capillaries and furcated chaetae with unequal ends and internally hairy ( Figs 7, 8 , 10 ). Thoracic neuropodia rounded with two crenulated capillaries chaetae, one single neuropodial acicular spine in the segments and six slender, smooth hooks ( Figs 5, 6 , 11 ); abdominal neuropodia with post-chaetal lobe and only crenulated capillaries ( Fig. 7 ). Anal papillae absent. Pygidium with one pair of cirriform anal cirri ( Fig. 12 ).

Color. Preserved specimens are yellowish opaque.

Remarks. Scoloplos maranhensis sp. nov. can be clearly placed in the genus Scoloplos due to the position of the branchiae and the presence of thoracic neuropodial hooks accompanied with capillary chaetae ( BLAKE, 2000; ZHADAN et al., 2015). The main distinctive characters of S. maranhensis sp. nov. is the thoracic notopodia with seven crenulated capillary chaetae, neuropodia with two crenulated capillaries and six slender-smooth hooks. Only four species may have 12 thoracic segments with branchiae first appearing on the 12 th segment: Scoloplos texana Maciolek & Holland,

Description of Scoloplos maranhensis sp. nov. ( Orbiniidae ,... OLIVEIRA et al.

1978 from Gulf of Mexico, Scoloplos intermedius ( Hartman, 1965) from New England, Scoloplos armiger (Müller, 1776) from Denmark and Scoloplos suroestense Blake, 2017 from Punta Suroestense, Chile Bay ( Tab. I). However, in all these three species both characters are variable ( HARTMAN, 1965; MACIOLEK & HOLLAND, 1978; MACKIE, 1987; BLAKE, 2017), while in all the 12 specimens of S. maranhensis sp. nov. examined here the thorax had exactly 12 chaetigers long and the branchiae always first appeared in this last thoracic segment ( Tab. I). Scoloplos armiger also always have 12 thoracic segments ( UEBELACKER & JOHNSON, 1984) likewise S. maranhensis sp. nov., however they differ in the position of the first branchiae, in the 10 th and 12 th segment respectively ( Tab. I). Other characteristics differing these species from S. maranhensis sp. nov. include: i) the prostomium shape, conical in S. maranhensis sp. nov. and pointed and/or triangular in the others; ii) the absence of anal cirri in S. suroestense ; iii) the presence of papillae in S. armiger and S. intermemdius ; and iv) the chaetal arrangement of S. texana including, for instance, serrated hooks in the neuropodia from thoracic chaetae which are smooth in S. maranhensis sp. nov. ( Tab. I and references therein).

Etymology. The species was named in reference to Maranhão, the State with the largest coastline from Brazil form where S. maranhensis sp. nov. was found.

Habitat. Muddy mangrove substrate with temperature between 25.7 and 27.8°C and salinity between 11 and 30.

Geographical distribution. Atlantic Ocean, Brazil, Quebra Pote Mangrove , São Luís , Maranhão State (02°41.344’S; 044°12.604’W) .

Description of Scoloplos maranhensis sp. nov. ( Orbiniidae ,... OLIVEIRA et al.

Iheringia, Série Zoologia, 109: e2019009 6

Description of Scoloplos maranhensis sp. nov. ( Orbiniidae ,... OLIVEIRA et al.

Iheringia, Série Zoologia, 109: e2019009 7

Description of Scoloplos maranhensis sp. nov. ( Orbiniidae ,... OLIVEIRA et al.

Iheringia, Série Zoologia, 109: e2019009 8

Figures

Figs 2-4. Scoloplos maranhensis sp. nov., holotype: 2, general view; 3, 4, detail of the anterior region with the prostomium and the smooth proboscis. Scales: Fig. 2: 2 mm; Figs 3, 4: 0.5 mm.

Figs 5-8. Scoloplos maranhensis sp. nov., anterior view of parapodium of the paratype: 5, parapodium 7, capillary notopodial chaetae and crenulate neuropodial chaetae; 6, Parapodium 7, notopodial lobe; 7, parapodium 18; 8, parapodium 30, furcate chaetae. Scales: Figs 5, 6: 0.1 mm; Fig. 7: 0.2 mm; Fig. 8: 0.05 mm.

Figs 9-12. Scoloplos maranhensis sp. nov.: 9, crenulate chaetae; 10, furcate chaetae (black arrow); 11, detail the smooth hooks; 12, detail of posterior region with the pygidial cirri. Scales: Figs. 9, 10: 0.1 mm; Fig. 11: 0.01 mm; Fig. 12: 0.5 mm.