DESCRIPTIONS OF TWO NEW SPECIES OF ENTOMOSTRACAFROM COLORADO, WITH NOTES ON OTHER SPECIES.By G. S. DoDDs,Of the Department of Zoology, University of Missouri, Columbia, Missouri.
The following notes and descriptions are based upon material col-lected by the author during four seasons spent at the Summer Moun-tain Laboratory of the University of Colorado, at Tolland, Colorado.The laboratory is at an elevation of about 8,900 feet, at the edgeof an area with a large number of small glacial lakes, in which isfound an abundant entomostracan famia.Subclass PHYLLOPODA.Order ANOSTRACA.Family STREPTOCEPHALIDAE.STREPTOCEPHALUS COLORADENSIS, new species.J/aZe.?The frontal appendage is finger-shaped and reaches toabout three-fourths of the length of the first joint of the secondantennae. The first antennae are slender, shghtly tapering, andreach about to the end of the first joint of the second antennae. ' Thesecond antennae are of the usual three-jointed type of the genus.The first joint is about twice as long as wide, very sfightly curvedbackwards, and has the front margin decidedly longer than theback. It is slightly narrower at the distal than at the proximal end.The appendage at the posterior distal margin is about as long as thejoint itself, is slender and moderately tapering. The second joint ismuch more slender than the first and just a little shorter. It is bentabruptly at about the middle. The third joint is shorter than eitherof the others and bears two long appendages wliich cross each otherscissors fashion, the proximal one being on the outside. Theseappendages are directed in a downward and posterior direction.The proximal one has a length about equal to the combined lengthof the first two joints of the antenna. Its proximal two-fifths' isflattened and its forward margin is roUed inward, forming a veryProceedings U. S. National Museum, Vol. 49?No.2096.81022??Proc.N.M.vol.49?15 7 97
gg PROCEEDINOFi OF THE NATIONAL MUSEUM. vol.49.decided concavity. At the posterior distal margin of this portion isa short fingerhke process which is not hooked over the other ap-pendage as in S. sealii Ryder. The rest of the appendage is a slen-der structure with an elbowlike bend at about its proximal third,beyond which it tapers uniformly and curves slightly forward. Thedistal appendage of the third joint is about two-thirds as long as theproximal. Just a little short of the middle it curves rather sharplyforward thi-ough nearly 90?. The portion proximal to this bend bearson its anterior margin two fingerhke processes, the distal of which isabout twice as long as the proximal. Beyond the bend, this appendageis slightly curved backward and tapers to a point. (Fig. 1.) The
Fig. 1?Streptocephalus coloradensis. Fig. 2.?Streptocephalus coloradensis.Head op male. X 8. Head of female. X 8.
coiled vas deferens appears externally on the side of the 13th segment.The two penes are nearly in contact at their extremities and reachnot quite to the middle of the 15th segment.Average length 22 mm.Female.?The first antennae are as in the male. The secondantennae are of the usual broad and flattened type and are about aslong as the first. The end is rounded, but bears a small spinehkeoutgrowth at the inner distal margin. (Fig. 2. ) The ovisac is abouthalf the diameter of the abdomen, arises from the 14th postcephalicsegment, and reaches about to the middle of the 18th. The eggs areof moderate size and are arranged in four definite rows.Average length 23 mm.In both sexes there are 1 1 pairs of swimming feet.This species is common in two ponds near Eldora, Colorado, in theFront Range of the Rocky Mountains at an elevation of 8,500 feet.I collected material here during the summers of 1913 and 1914. Acollection recently sent me from Fort Collins, Colorado, near the
NO. 2096. NEW ENTOMOSTRACA FROM COLORADO?DODDS. 99western edge of the great plains, contains an abundance of thisspecies.Type-locality.?Sulphide Pool, near Eldora, Colorado.TVpe.?Male, Cat. No. 47876, U.S.N.M.; paratype, female, Cat.No. 47876, U.S.N.M. Subclass COPEPODA.Order EUCOPEPODA."Family CENTROPAGIDAE.DIAPTOMUS ARAPAHOENSIS, new species.This is a red species of moderate size. The ceplialothorax is mod-erately slender, with its greatest width about the middle (posteriormargin of second segment). The last segment is produced posteriorlyon either side into a somewhat triangularlob considerable size, less pronounced inthe male than in the female. Each lobebears two small spines, one at the distalangle, and the other at about the middle ofthe inner dorsal margin. The first segmentof the female abdomen is slightly less inlength than the two following. Its greatestwidth is somewhat beyond the n\iddle, backof which it becomes abruptly narrower. Itbears two spines on either side, a moderate-sized one at the point of greatest width, and asmaller one about halfway between this pointand the posterior end of the segment. Thesecond segment is indistinctly separated fromthe first, is sHghtly shorter than the third, andits length is slightly less than its width. The furcal rami are a littleshorter than the third segment, are cUiated on the inner margin andhave a few cilia on the outer margin also. (Fig. 3.) The female an-tennae reach slightly beyond the end of the cephalothorax. The maleantennae are relatively longer, reaching beyond the middle of the abdo-men. The male right antenna is moderate!}'' enlarged. Its antepenul-timate segment bears a slender, straight process, which reaches aboutto the middle of the ultimate segment. (Fig. 4.) The first basalsegment of the female fifth foot bears the customary small spine.The lateral hair of the second basal segment is slender. The firstsegment of the exopodite is a little more than twice as long as broad.The claw of the second segment is slightly smuous, its inner marginis finely denticulate, and its outer margin bears some small spines.There is a small spine at the outer distal margin of this segment.
Fig. 3.?Diaptomus arapahoen.SIS. Abdomen of female-X50.
100 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 49.The third segment is distinct and unusually well developed. It bears itwo spines, the inner of which is shghtly setose and about twice aslong as the outer one. The endopodite re^;' hes about tothe middle of the first segment of the exopodite and bearstwo or three small spines near its tip. (Fig. 5.) Thespine of the first basal segment of the male fifth feet isof moderate size. The second basal segment of the rightfoot is about one-fourth longer than wide and bears, atabout the middle of its inner surface, a small hyahneappendage. The lateral hair is slender and arises at aboutthe beginning of the distal third of the segment. Thefirst segment of the exopodite is short and its outer mar-ghi is much longer than the inner. At its outer distalangle it bears a hyaline appendage. The second segmentis about twice as long as broad, having its greatest widtha httle beyond the middle. From this point arises thelateral spine, which is about as long as the segment, nearlystraight, and uniformly tapering to a sharp point. Itextends in a direction but little divergent from the axis ofthe segment. Its inner margin is very finely denticulate.This segment has a small crescent-shaped hyaline elevationabout the middle of its posterior surface. The terminalhook is considerably longer than the rest of the exopoditeand tapers to a very fine point. It is falciform, witlislightly recurved tip, and is finely denticulate on its inner margin.The endopodite reaches to about the middle of the second segmentof the exopodite, and is moderately pointed at the tip,near which are a few very small spines. The left fifthfoot, exclusive of the long appendages, reaches a Uttlebeyond the end of the first segment of the right exopo-dite, and including the appendages, extends nearly to theend of its second segment. The second basal segment ofthis foot is about one-fourth longer than broad. Thereis a small hyaline appendage on its inner margin just alittle short of the middle and the lateral hair arises atthe end of the second third of the outer margin. Thecombined length of the two segments of the exopoditeabout equals the length of the second basal segment.The first segment of the exopodite is about half as wideat its distal as at the proximal end and its inner surfacebears a setose pad. The second segment is somewhatshorter than the first and there is a prominent setose padon its inner surface. The curved terminal processes almost equalthe combined length of the two segments. The outer one is blunt
Fig. 4.? Di-A P T O M U SARAPAHOEN-sis. LastTHKEE SEG-MENTS OFEIGHT AN-TENNA OFMALE. X188.
Fig. 5.? Di-APTOM usARAPAHOEN-sis. FifthFOOT OF FE-MALE. X82.
i
NO. 2096. 1\^EW ENTOMOSTRAVA FROM COLORADO?DODDH. 101
Fig. 6.?Diaptomusarapahoensis. fifthfeet of male. x 82.
at the tip and bears on its convex (inner) surface a row of smallteeth. The inner one is more slender, tapers uniformly to a finepoint, and is fl.nely setose. The endopodite nearlyequals the exopodite in length and bears near thetip a few very small spines. (Fig. 6.)Length of female, 2.1 mm. Length of male, 1.7mm. These are the measurements in the lakeswhere they attain the greatest size. In one lakethey were respectively 1.6 and 1.35 mm.I have found this species in four mountain lakesin Colorado at elevations of about 11,000 feet.Three of these lakes, known locally as the Arap-ahoe Lakes, are located just east of the Conti-nental Divide a short dis-tance from the railroad sta-tion Corona, on Rollins Pass.The fourth locality is alake about 12 miles farthernorth. Diaptomus shoshoneForbes is also foimd in each of these lakes.Type-locality.?South Arapahoe Lake, Colo-rado.Type.?U^lQ, Cat. No. 47878, ^U.S.N.M. Paratype, female,Cat. No. 47878, U.S.N.M.DIAPTOMUS LINTONI Forbes.
FIG 7.-DIAPT0MUS LINTONI. ^his spcclcs was collccted andLast three segments of described by Forbes ^ from Yel-MALE EIGHT ANTENNA, SHOW- -i , "r)TT_ li- 1iNG THE TWO EXTREMES OF lowstonc Park where he foundTHE APPENDAGE OF THE it " common lu lakcs aud pools."ANTEPENULTIMATE SEGMENT. i xl ' i. T- j. ? !_^ ij^s. Apparently it has not smce beencollected until it appeared inmy collections from Colorado. During the summersof 1908, '12, '13, and '14, I have found it as an impor-tant part of the fauna of two lakes, known as TellerLakes, near the town of Tolland, Colorado, at an ele-vation of 9,575 feet. Though collections were at thesame time made from a considerable number of other lakes in thesame region, the species was found only in these two lakes. Forbesstates that in Yellowstone Park it occurs commonly with D.slioshone.The two lakes in which I have found the species are just about at thelower altituduial range of B. shoshone in this region. In one of them itforms a minor part of the fauna and in the other I have never found it.
Fig. 8.?DiAPTOMuaLINTONI. Termi-nal SEGMENTS OFmale RIGHT AN-TENNA. Copiedfrom figure ofForbes.
1 S. A. Forbes, A preliminary report on the aquatic invertebrate fauna of the Yellowstone National Park,Wyoming, and of the Flathead region of Montana. Bull. U. S. Fish Com., 1S91, pp. 207-258.
102 PliOCEEDlNaS OF THE XATIONAL MVBEUM. VOL. 40.These specimens agree well with the description of Forbes except inone particuhir which seems worthy of comment. He figures the ante-penultimate segment of the male right antenna with a straiglit process,though in his description he does not state whether it is straight orcurved. Marsh/ in his key, interprets it as a straight process. Inmy material this process is always decidedly curved,though it varies considerably in length. The condi-tions represented in figure 7 show the two extremesbetween which most specimens lie. Figure 8 is a copyof Forbes's drawing from the Yellowstone material.DIAPTOMUS SHOSHONE Forbes.This is the most common Copepod in the mountainswest of Denver, where I have collected it at elevationsfrom 9,575 to 12,188 feet, but mostly in lakes above11,000 feet. It ranges along the highest parts of theRocky Mountain range, havmg been collected byForbes in the Yellowstone region and by Ward^ atPikes Peak. Though Forbes does not figure the femaleabdomen, he describes it as being asym-metrical. Marsh 2 states that in thePikes Peak material he does not findthis to be the case as does also Schacht^ who studiedForbes's collections. Marsh's figures, however, draAvn,I suppose, from the Pikes Peak material, show the firstsegment of the female abdomen as distinctly asymmet-rical. In my collections this asymmetrical conditionprevails, as illustrated in figure 9. Marsh mentions thefact that he finds the endopodite of the female fifthfoot and of the left male fifth foot to be indistinctly two-segmented. This is also the case with my specimens.It may also be worthy of note that in some lakes theappendage of the antepenidtimate segment of the maleright antenna is much longer than is the general rule,reaching well beyond the end of the ultimate segment.
Fig. 9.?DiaptomussuosHONE. FemaleABDOMEN. X 50.
DIAPTOMUS LEPTOPUS, var. PISCINAE Forbes. Fig. 10.?DiaptomusLEPTOPUS, var. pis-cinae. TerminalSEGMENTS OF MALERIGHT ANTENNA.X 1S8.This is the most common representative of the genusin the lakes of the ToUand region below 11,000 feet.In all my specimens the hyaline lamella of the ante-pemdtimatc segment of the male right antenna is expanded at thedistal end into a very decided angle, as seen in figure 10. So faras I know, this has not been mentioned or figm-ed for material fromother localities.
1 C. Dwight Marsh, A revision of the genus Diaptomus. Trans. Wis. Acad., vol. 15, pt. 2, 1907, pp. 3S1-486.2 C. Dwight Marsh, Report on the Copepoda, In A biological reconnaissance of some elevated lakes in theSierras and the Rockies, by Henry B. Ward. Studies from Zool. Lab. Univ. of Nebr., vol. 3, 1904, pp.146-149.
? F. W. Schacht, The North American species oVDiaptomus. Bull. 111. State Lab. Nat. Hist., vol. 5, art.3, 1897.