Pelagic tunicates (Appendicularia and Thaliacea) of Sri Lanka: two first records with an annotated checklist Author Karunarathne, Krishan D. 0000-0003-1780-9749 Department of Aquaculture and Fisheries, Faculty of Livestock, Fisheries and Nutrition, Wayamba University of Sri Lanka, Makandura, Gonawila, 60170, Sri Lanka. & krishankarunarathne @ gmail. com; krishan. dk @ wyb. ac. lk; https: // orcid. org / 0000 - 0003 - 1780 - 9749 krishankarunarathne@gmail.com Author Croos, M. D. S. T. De 0000-0003-4449-6573 Department of Aquaculture and Fisheries, Faculty of Livestock, Fisheries and Nutrition, Wayamba University of Sri Lanka, Makandura, Gonawila, 60170, Sri Lanka. & dileepa _ dc @ yahoo. com; dileepad @ wyb. ac. lk; https: // orcid. org / 0000 - 0003 - 4449 - 6573 dileepa_dc@yahoo.com text Zootaxa 2021 2021-11-11 5067 3 352 376 journal article 3575 10.11646/zootaxa.5067.3.2 9b8d33b9-c9df-4f9d-abeb-de1c7b84f3e0 1175-5326 5681899 AF3DF45F-B248-4BDD-904F-F55D735DC867 Key to the Thaliacea species of Sri Lanka (based on Smith et al. 1901 , Van Soest 1973 , 1974a , b, 1981, 1998; Madin & Harbison 1978 ; Godeaux 1998 ; Kim et al . 2011 , 2017 ; Gershwin et al . 2014 , Purushothaman et al . 2017 ; Adam & Ishak 2018 ; Ishak et al . 2018 ) 1 Colonial or solitary; zooids not embedded in a common, tube-shaped matrix...................................... 6 - Colonial; zooids embedded in a common, tube-shaped matrix: Family Pyrosomatidae ............................... 2 2 Colony entirely smooth.............................................................. Pyrosomella verticillata - Colony with longer or shorter projections or denticulations.................................................... 3 3 Colony with longer or shorter truncate processes comprising oral siphons......................................... 5 - Colony with short triangular denticulations lying dorsal to the opening of the oral siphon............................ 4 4 Test thick and opaque; ascidiozooids longer than high, with angular endostyle................... Pyrostremma spinosum - Test thin and transparent; ascidiozooids as high as long, with a curved endostyle................... Pyrostremma agassizi 5 Colony small (about 20 mm ); oral siphon of ascidiozooids as broad as the branchial basket.......... Pyrosoma aherniosum - Colony larger (about 50 mm ); oral siphon much narrower than the branchial basket................. Pyrosoma atlanticum 6 Smallish; body muscles in complete parallel rings around the body; intestine forming an arch in gonozooid and oozooid / nurse: Family Doliolidae .................................................................... Doliolum denticulatum - Largish; body muscles often incomplete and nearing or fusing: Family Salpidae .................................... 7 7 Without stolon; bearing gonads, one or more eggs or embryos (blastozooid / aggregate form)........................ 24 - With a stolon ventrally or posteriorly; gonads absent (oozooid / solitary form)..................................... 8 8 Gut usually bent into a more or less compact loop posteriorly and not accompanying the branchial bar; luminous organs always absent............................................................................................. 11 - Gut straight overlying the branchial bar; luminous organs present or absent; seven annular body muscles generally interrupted ventrally............................................................................................ 9 9 Dorsal longitudinal muscles present................................................... Cyclosalpa quadriluminis - Dorsal longitudinal muscles absent...................................................................... 10 10 Luminous organs absent................................................................... Cyclosalpa affinis - Luminous organs present............................................................... Cyclosalpa floridana 11 Less than eight body muscles........................................................................... 19 - Eight or more body muscles............................................................................ 12 12 Without two posterior processes / tails.................................................................... 14 - With two posterior processes / tails...................................................................... 13 13 Nine to 12 body muscles, widely interrupted ventrally; test firm, with finely denticulated longitudinal ridges................................................................................................. Metcalfina hexagona - Sixteen to 22 body muscles, all interrupted dorsally and ventrally; test firm, thick and papillated............. Thetys vagina 14 Eight or 9 body muscles, M I to M IV fused or closely approaching dorsally; test soft, smooth, elongated cylindrical............................................................................................... Iasis cylindrica - Nine or more body muscles parallel to each other, or M I to M III fused or approaching dorsally...................... 15 15 Nine body muscles, with ventral interruptions not widening toward the posterior end............................... 17 - Nearly parallel body muscles, with ventral interruptions widening toward the posterior end.......................... 16 16 Nine to 18 body muscles................................................................. Ritteriella retracta - Nineteen to 31 body muscles................................................................ Ritteriella picteti 17 All body muscles parallel to each other; test smooth................................................ Salpa maxima - Muscles I to M III fused or nearing dorsally............................................................... 18 18 Muscles VIII and M IX parallel or converging but not fusing, test ridges longitudinal and serrated............ Salpa aspera - Muscles VIII and M IX strongly fused dorsally; test entirely smooth................................. Salpa fusiformis 19 Five broad body muscles interrupted dorsally and ventrally......................................... Soestia zonaria - Four or five narrow body muscles, continuous dorsally...................................................... 20 20 Five body muscles; test bearing projections................................................................ 22 - Four body muscles firmly fused dorsally in two groups (M I–II and M III–IV); test barrel-shaped without projections..... 21 21 Atrial musculature reduced............................................................... Pegea confoederata - Atrial musculature complicate............................................................... Pegea bicaudata 22 Body globular; several projections bulging into the test, some of them beyond it............. Traustedtia multitentaculata - Body cylindrical, with two posterior projections............................................................ 23 23 Atrial palps simple and straight........................................................... Thalia democratica - Atrial palps bifurcate....................................................................... Thalia sibogae 24 With a compact nucleus; four or more body muscles; luminous organs always absent............................... 27 - Without a compact nucleus; four body muscles; one pair of luminous organs may be present......................... 25 25 Luminous organs present........................................................... Cyclosalpa quadriluminis - Luminous organs absent............................................................................... 26 26 All body muscles free dorsally.............................................................. Cyclosalpa affinis - Muscles (M I–II and M III–IV) strongly fused dorsally, both groups nearing or touching in the mid-dorsal line............................................................................................... Cyclosalpa floridana 27 Five or six body muscles.............................................................................. 30 - Four body muscles................................................................................... 28 28 Posterior projections absent.............................................................. Pegea confoederata - Posterior projections present........................................................................... 29 29 Test firm and cylindrical, with two short posterior projections...................................... Pegea bicaudata - Test soft and globular, with three long posterior projections.............................. Traustedtia multitentaculata 30 Six body muscles.................................................................................... 35 - Five body muscles................................................................................... 31 31 Two groups of body muscles continuous, fussing or touching dorsally........................................... 33 - Body muscles parallel or approaching dorsally............................................................. 32 32 Broad and parallel body muscles, interrupted ventrally, M I interrupted dorsally; test very firm, with a posterior projection........................................................................................... Soestia zonaria - Narrow and short body muscles, interrupted dorsally and ventrally; test firm, with longitudinal rows of spines.. Thetys vagina 33 Muscles I–III and M IV–V fusing or touching dorsally; body fusiform................................ Iasis cylindrica - Muscles I–III and M IV–V separately dorsally, the total number of muscle fibers (M I–V) 15 to 17 (usually 16); body oval 34 34 Test smooth........................................................................... Thalia democratica - Test papillated............................................................................. Thalia sibogae 35 Body muscles asymmetrically arranged.................................................... Metcalfina hexagona - Body muscles symmetrically arranged into three dorsal groups, M I–II, M III–IV and M V–VI; test thick and firm; body fusiform.............................................................................................. 36 36 Muscles I–II and M III–IV equally fused dorsally, both groups touching or approaching dorsally..................... 38 - Muscles I and M II more strongly fused than M III–IV....................................................... 37 37 Number of muscle fibers 60–109........................................................... Ritteriella retracta - Number of muscle fibers 110–169............................................................ Ritteriella picteti 38 Both anterior and posterior projections echinated, posterior projection with a bifid appearance............... Salpa aspera - Test completely smooth............................................................................... 39 39 Muscle groups I–II and M III–IV closely approaching dorsally, M IV and M V not approaching laterally...... Salpa maxima - Muscle groups I–IV fused dorsally, M IV and M V fused laterally................................... Salpa fusiformis