5 p. : ill. ; 24 cm.Includes bibliographical references (p. 5)

Allan Hancock Foundation.

Reish, Donald J.

Treadwell, Aaron L. (Aaron Louis), 1866-1947.

American Museum of Natural History Scientific Publications

AMERICAN MUSEUMNOVITATESPUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORYCITY OF NEW YORK SEPTEMBER 1, 1950 NUMBER 1466REDESCRIPTION OF THE POLYCHAETOUSANNELID TrPOSrLLIS ACICULATATREADWELL1BY DONALD J. REISHThe purpose of this paper is to detail the specific characters ofa member of the family Syllidae, Typosyllis aciculata Treadwell(1945, pp. 1-2), so as to permit its comparison with some othermembers of the genus which occur in the same or adjacent geo-graphic areas. Examination of the holotype and paratype speci-mens reveals that the affinities of the species are with somespecies that have a widely reported range (see discussion below).I am indebted to Mr. John C. Armstrong, Assistant Curatorof Invertebrates, the American Museum of Natural History, forthe loan of type materials. This study was conducted at theAllan Hancock Foundation of the University of Southern Cali-fornia; to its administration I acknowledge thanks for the useof material aid.Typosyllis aciculata TreadwellDESCRIPTION: Two small specimens come from among rocksat Pacific Grove, California, July 19, 1939. The holotype, intwo pieces, measures 8.5 mm. in length and 0.65 mm. at itsgreatest width which is around the twentieth setigerous segment.There are 76 setigerous segments in the holotype and over 80in the paratype. The paratype lacks a posterior end. *Theworm is brown, with dark intersegmental furrows.The prostomium (fig. 1) is pentagonal in shape and slightly1 Contribution from the Allan Hancock Foundation, University of SouthernCalifornia, Los Angeles.7451~\ 682_ / 3FIGS. 1-8. Typosyllis aciculata Treadwell. 1. Anterior end, holotype.Scale: 0.1 mm. 2. Sixteenth parapodium, holotype; six composite setaeomitted. Magnification as in figure 1. 3. Sixty-eighth parapodium, holotype;five composite and one simple setae omitted. Magnification as in figure 1.4. Aciculum from sixty-eighth parapodium, holotype. Scale: 0.03 mm.5. Superior composite seta from sixty-eighth parapodium, holotype. Magnifi-cation as in figure 7. 6. Inferior composite seta from sixty-eighth parapodium,holotype. Magnification as in figure 7. 7. Superior simple seta from sixty-eighth parapodium, holotype. Scale: 0.01 mm. 8. Inferior simple seta fromsixty-seventh parapodium, holotype. Magnification as in figure 7.REDESCRIPTION OF TYPOSYLLIS ACICULATAbroader than long. It bears a pair of palps, three antennae, andtwo pairs of eyes. The palps are joined at their bases for one-third their length; they are triangular in shape and about twiceas long as wide. The median antenna arises behind the mid-point of the posterior eyes. The lateral antennae originatejust in front of the anterior pair of eyes. They are articulated,each with a long base and 13 articles. The four eyes are intrapezoidal arrangement with the anterior pair, which are pro-vided with a lens, farther apart and twice as large as the posteriorpair.The peristomium bears two pairs of moniliformed tentacularcirri with the dorsal pair composed of 17 articles and the ventralpair of 10 articles.The pharynx, which is smooth at its anterior margin, is sixsegments long and extends from the fourth to the ninth setigeroussegment. There is a single, colorless, anterior tooth.The proventriculus begins at the tenth setigerous, and extends,for eight segments, to the seventeenth segment.The anterior parapodial lobes are rectangular in shape (fig. 2);each has an articulated dorsal cirrus, a conical lobe with a single,pale yellow aciculum and six to 10 composite setae, and a short,slender, ventral cirrus. The anterior dorsal cirri are composedof 20 to 23 articles.The posterior parapodia (fig. 3) are smaller in size than thosein front, but they are rectangular as are those in front. Theseposterior lobes have single, large, pale yellow, superior acicula(fig. 4); they have a smooth tip that projects beyond the tissuein the posterior lobes. Acicula in the anterior segments aresmaller in size than those in back. There are five to six compositesetae in the posterior lobes. The ventral cirrus is short andslender as in the anterior lobes.The pale yellow compound setae vary little in anterior, middle,and posterior body regions, but within a lobe the appendage inthe superior setae (fig. 5) is longer than those inferior (fig. 6).The appendage has an apical and subapical tooth and a numberof spinelets along the cutting edge. One side of the shaft bearsthree or four spines.There are two kinds of simple setae present in posterior seg-ments. In one the end has an entire tip (fig. 7), and in the otherthere is a subapical tooth (fig. 8). The entire ones are locatedjust below the aciculum, and the bifid ones are below the com-1950 3AMERICAN MUSEUM NOVITATESposite setae. Both kinds of simple setae were not observedwithin the same lobe, but since many setae have been broken, itis impossible to determine what the exact condition is. In theholotype no simple setae were observed anterior to segment 68.In the paratype, however, only simple setae with an entire tipoccur at least from segment 55, but, as with the holotype, anumber of setae have been broken.There is only one anal cirrus remaining; it is composed of16 articles.The holotype is No. 3386 and the paratype is No. 3365 in thecollections of the American Museum of Natural History.REMARKS: In the original account, the palpi were describedas asymmetrical and entirely separated at their base. How-ever, in both holotype and paratype specimens one palpus ispartially turned under, thus giving it an asymmetrical appear-ance; actually they are symmetrical. The palpi are fused forone-third their length, as shown in figure 1. Contrary to thefirst account, the median antenna is present, on the holotype.I find the pharynx to begin at the fourth setigerous segment, notthe sixth setigerous segment. Figure 2 of the original report is ofa median parapodium which was described as being roughlyconical in outline and bearing a dorsal cirrus composed of 53articles. No lobe was observed to have this shape, and no dorsalcirrus was seen with more than 23 articles. In figure 3 of theoriginal account the dorsal surface is down instead of up, asshown by the position of the aciculum. Only simple bifid setaewere described in the first report which possibly are the setaerepresented in figure 8. No simple setae with an entire tip weredescribed.DISCUSSION: The genus Typosyllis Langerhans, 1879, is alarge, ill-defined category with many species for which theaffinities are poorly understood. As herein defined, I refer tothose species that have similar composite setae in all parapodiaand that may or may not have simple setae present in posteriorlobes. The prostomial antennae and dorsal cirri are jointedand often appear moniliform. The palpi are either well separatedor somewhat fused at their bases. The prostomial eyes numberusually four in various arrangements. The prostomial anten-nae consist of a median and a pair of lateral ones that are insertedon the dorsal surface.In these respects Typosyllis Langerhans, with type T. krohnii4 NO. 1466REDESCRIPTION OF TYPOSYLLIS ACICULATA(Ehlers), comes near Syllis Savigny, 1818, with type S. monilarisSavigny. As I here interpret the difference, in species of Typo-syllis Langerhans all parapodia have similar composite setaeand, if present, simple setae only in the posterior region; in thespecies of Syllis Savigny, restricted, there are simple setae in themiddle or anterior parapodia.Typosyllis aciculata Treadwell has affinities with T. variegata(Grube), T. krohnii (Ehlers), and T. prolifera (Krohn). Itagrees with these species in having composite setae with a sub-apical tooth in all parapodia and simple setae both above andbelow in the posterior lobes.Typosyllis aciculata differs notably from these species in thefollowing respects: (1) the number of articles in the dorsal cirris the same; they do not alternate long and short; (2) the simplesetae in T. aciculata are entire above and bifid below; in T.variegata and T. prolifera all simple setae are bifid; in T. krohniithe simple setae are as in T. aciculata; and (3) the number ofarticles in the antennae and tentacular cirri in T. aciculata isfewer than for the other species (Fauvel, 1923, pp. 259-262).Typosyllis variegata, T. prolifera, and T. krohnii have been re-ported from the European area, but only T. variegata has beentaken from eastern Pacific waters. Here it is known from theGalhpagos Islands and Panama (Monro, 1933, pp. 28-9) andfrom Acapulco, Mexico (Rioja, 1941, p. 694).LITERATURE CITEDFAUVEL, PIERRE1923. Polychetes errantes. Faune de France, vol. 5, 488 pp., 188 figs.MONRO, CHARLES CARMICHAEL ARTHUR1933. The Polychaeta errantia collected by Dr. C. Crossland at Colon, inthe Panama region, and the Galapagos Islands during the expeditionof the S. Y. St. George. Proc. Zool. Soc. London, pt. 1, pp. 1-96,36 figs.RIoJA, ENRIQUE1941. Datos para el concocimiento de la fauna de poliquetos de las costasPacifico de Mexico. An. Inst. Biol., Mexico, vol. 12, pp. 660-746,llpls.TREADWELL, AARON L.1945. New species of polychaetous annelids from Massachusetts andCalifornia. Amer. Mus. Novitates, no. 1280, pp. 1-3, 8 figs.1950 5

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