The Orbiniidae (Annelida: Polychaeta) of Pacific Costa Rica Author Dean, Harlan K. Author Blake, James A. text Zootaxa 2015 3956 2 183 198 journal article 10.11646/zootaxa.3956.2.2 cc2e6574-6d74-4c04-a6fb-b5a63e67fc81 1175-5326 237218 80102A8C-F6C0-43C4-81A1-B33E10EE889E Leitoscoloplos panamensis ( Monro, 1933 ) Figures 1 (D–F), 2 (B) Haploscoloplos panamensis Monro, 1933 :1045 –1046, Fig. 1 A–D.— Fauchald, 1977 : 46 . Not Hartman, 1957 : 277 , pl. 28, 1– 3 (= Scoloplos alaskensis ) Fide Mackie, 1987 . Leitoscoloplos panamensis: Mackie, 1987 : 19 –20, Fig. 20.— Hernández-Alcántara & Solís-Weiss, 1999 : 27 ; 2014: 146‒149. Material examined . Gulf of Nicoya: Sta. 22, 9°48ˊ25″N, 84°52ˊ40″W, 22 m , muddy sand, 10 Jul 1980 (1); Sta. 29, 9°54ˊ55″N, 84°45ˊ15"W, 18 m , muddy sand, 27 Jan 1980 (1), 7 Jun 1981 , 1 ( MZUCR ); Bahia Culebra: Sta. 1, 10º35ˊ24.8″N, 85º39ˊ41.6″W, 1.5 m, 19 May 2011 (2); Sta. 2, 10º35ˊ51.8"N, 85º39ˊ24.7"W, 18 m , 19 May 2011 (2); Sta. 4, 10º35ˊ26.7″N, 85º39ˊ16.8"W, 6 m , 19 May 2011 , 1 ( MZUCR ); Sta. 21, 10º37ˊ12.7″N, 85º38ˊ31.2″W, 16 m , 19 May 2011 (3); Sta. 29, 9°54ˊ55″N, 84°45ˊ15″W, 18 m , muddy sand, 7 Jun 1981 (1). Jicaral, intertidal, 9º58ˊN, 85º06ˊW, mangrove roots Jan 1996, 1 ( MZUCR ). Description. All specimens incomplete, maximum thoracic width 0.18–0.74 mm ( Fig. 2 B). Prostomium conical, longer than wide, eyespots lacking; paired dorsolateral nuchal organs present. Peristomium subequal in length and width to first segment, about two-thirds prostomial length. Thorax 12–17 setigers long. Branchiae from setiger 9 in all specimens, short, papilla-like at first, increasing in length and width posteriorly. Thoracic notopodial postsetal lobes triangular, increasing in length posteriorly; neuropodial postsetal lobes mammiliform in setigers 1‒9 of specimen with 17 thoracic setigers; bifurcate in subsequent thoracic setigers; mammiliform in setigers 1‒7, bifurcate in remaining thoracic setigers of specimens with 12 and 13 thoracic setigers ( Fig. 1 D). Single, small papilla on last 2‒3 thoracic setigers, 2‒3 papillae on subsequent 4‒5 abdominal setigers ( Fig. 1 E). Interramal cirri on first five abdominal setigers; accompanied by triangular notopodial postsetal lobe; neuropodial postsetal lobe bifurcate ( Fig. 1 E). Notopodial postsetal lobe widens, becoming foliaceous in midabdominal setigers ( Fig. 1 F), then longer and more narrow posteriorly; neuropodial postsetal lobe reduced, only weakly bifurcate in posterior abdominal setigers, lateral branch smaller than medial; subpodial flange present ( Fig. 1 F). Notosetae and neurosetae camerated capillaries throughout, densely packed in thoracic parapodia, reduced to 2‒3 weakly camerated capillaries in abdominal neuropodia ( Fig. 1 F); furcate setae absent. Remarks. This species was originally described by Monro (1933) from shallow water muds in Pacific Panama . The thorax was 17 setigers long and the branchiae were reported to begin on setiger 12; however, Mackie (1987) examined Monro’s type material and reported that the branchiae actually began on setiger nine which is true of the Costa Rica specimens. L . panamensis is most similar to L . bifurcatus and L . multipapillatus in possessing branchiae from setiger nine. L . panamensis lacks the numerous stomach papillae of L. multipapillatus and has subpodial papillae which are lacking in L . bifurcatus . Distribution. This species has been previously reported from the Pacific coast of Panama ( Monro 1933 ) and the Gulf of California, Pacific Mexico ( Hernández-Alcántara & Solís-Weiss 1999 , 2014 ).