The eastern Mediterranean species, Porcellio (Proporcellio) quadriseriatus Verh. (which for some years has been locally very abundant near Southern Methodist University at Dallas), was first found in the summer and fall of 1925 in a rubbish- and stone dump on a corner of the campus

Geiser, S. W.

English

Southern Methodist University

1951) PoRCELLIO QUADRISERIATUS IN TEXAS 163 · Mexicd. Brittonia 6:121-302. 1947. FERNALD, M. L. Gray's Manual of Botany, 8th ed. 1950. Erigeron, pp. 1442-1444. GRAY, AsA. Synoptical Flora of North America, Vol. I - Part II. 1884. Erigeron, pp.-207-221. SMALL, J. K. Flora of the Southeastern United States. 1913. Erigeron, pp. 1229-1230. Porcellio quadriseriatus (Isopoda) at Dallas, Texas S. W. Geiser 1 The eastern Mediterranean species, Porcellio (Proporcel-lio) quadriseriatus Verh. (which for some years has been locally very abundant near Southern Methodist University at Dallas), was first found in the summer and fall of 1925 in a rubbish- and stone dump on a corner of the campus. 2 Again in 1927 I found it abundant in a restricted distribu-tion, and sent a dozen individuals (from a collection of several hundred) to the American Museum of Natural His-tory and the U.S. National Museum. In June and July of 1928 (repeated in 1929 and 1930) I again collected several hundred specimens from a compost heap on the campus, as well as in the University greenhouse. Many of the females contained young in their brood-chambers. As the species with us is minute and very active, most of my collections were taken with potato traps (Geiser, 1928), without loss of even very young and juvenile forms. More than a thousand individuals of this species were found in the above-mentioned localities during the last two weeks of May, 1932. All were "sexed" to learn the sex-ratio, and representative samples _of the two sexes were measured (Table I.) Many gravid females of the collection were also examined to determine the size of representative brqods (Tables II, Ill). In June, July, and September of 1936 I again found this species, this time in a mule barn east of the University power plant. I measured some thousand specimens of this collection (Table IV). Representative gravid females were again studied from those collections to ascertain brood-sizes; the data are summarized in Table II. Verhoeff (1917, p. 167) described this species from the type locality of Rehoboth near Jaffa, Palestine. In his 1923 paper (p. 225), Verhoeff gave measurements of the species as follows: 'males from Rehoboth (7.5 mm.) and Chuldah (9.5 mm.), and a young female from Rehoboth (4.5 mm.)' His measurements exceed greatly my usual findings for this species (as will be seen from my tables, especially Table IV). 1Professor of Biology. Southern Methodist University. DaJlas. 2Sce Geiser (1!)33. pp. 29-30), and Van Name (1936, pp. 236-38). 164 FIELD AND LABORATORY [Vol. 19 In my Jun~ 4-14, 1932 collection, the aver.age lengths of 377 males and 638 females were ca. 3.7 and 4.2 mm., respectively. In small unselected populations of adults only (Table I), greater lengths were found; but only a small percentage of the populations there given had a length in excess of 6.9 mm. Probably the specimens on which Verhoeff based his· de-scriptions were older, more conspicuous ones. In the 1936 collections (Table I), it is to be noted that those taken earlier in the year had a higher percentage of larger individ-uals; while the converse was true for collections taken later in the year. In the June 4-14, 1936 collection, 35% of the males and 22 % of the females had a length of 6 mm; in the July 4-14, 1936 collection, only 2% of tl;ie males and 6% of the females had that length. It appears probable that many of the older individuals die under field conditions with the onset of warm weather, and that there is greater survival~ among the younger individuals. 3 The brood-size with our Porcellio quadris(}riatus is much smaller than those reported for many other species. Pierce (1907), writing from Dallas, found broods of Porcellio laevis ranging from 8 to 30; Grave (1913), a maximum of 200 for Armadillidium vulgare, and a range for Porcellio scaber of 18-45. Collinge (1915) found the following ranges: Porcellio scaber (12-30), Armadillidium vulgare (30-60), and Onis-cus asellus (30-50). Hatchett (1947) in his monograph on the isopods of Michigan found ranges in brood-size for the species he especially studied as follows : A rmadillidium vul-gare ( 5-62) , Cylisticus convexus ( 10-40), Porcellio scab er (6-42), and Tracheoniscus rathkei (6-29). In his very care-ful studies he found a positive correlation (0.75) between the size of the females and the number of young carried in the brood-pouch. -This relation appears true also in my Porcellio quadriser-iatus, as Table II (and III) shows. In my 1936 individuals (Table II), the early-season gravid females were larger, and had Jarger average broods; later in the season the females were smaller, with fewer young in their marsupia. There was a marked tendency for greater body-length and larger broods to go together. The data of Table IV are of interest as showing the ratio 'Schobl (1880) found a very high mortality among gravid females of Porcellio ~raher, which he considered due to the highly-weakening ecdyses immediately preceding egg.laying, as a result of which the females succumbed in large numbers. 1951] PORCELLIO QUADRISERIATUS IN TEXAS 165 of the sexes in Porcellio quadriseriatus. Sex was determin-able in 2 mm. males, for at that age the characteristic cop-ulatory appendages were at least indicated. At lengths of less than 4 mm., the males were in excess, while the reverse was true in the larger classes. For the collection as a whole, the males constituted 37 % , and the females 63 % , of the population. LITERATURE CITED COLLINGE, WALTER E. Some observations on the life-history and habits of the terrestrial Isopoda (wood-lice). Scottuih Naturalist, 1915, 299-307. GEISER, S. W. A simple trap for the capture of terrestrial isopods. Amer. Midl. Nat., 11, 258059, 1928. ----Frequency of occurrence of albinism in terrestrial isopods. Field & Lab., 1, 4-7, 1932. [reports no albinos in a lot of about 1000 specimens of Porcellio quad-riseriatus (error: "Philoscia cf. muscorum".)] ----Notes on Texas Crustacea. Ibid., 2, 29-31, 59-60, 1933-34. [pp, 29-30.] ----Further observations on the sex-ratios of terrestrial isopods. Ibid., 3, 7-10, 1934. GRAEVE, WILHELM. Die in der Umgebung von Bonn vorkommenden landbewohnenden Crustaceen und einiges ueber deren Lebensverhaeltnisse. Verh. d. naturh. Ver. d. preuss. Rheinlande und Westfalens, 70, 175-248, 1913. HATCHETT, STEPHEN P. Biology of the Isopoda of Michigan. Ecological Monographs, 17, 47-79, 1947. PIERCE, W. DWIGHT. Notes on the economic importance of sowbugs. U.S. Bur. Ent., Bull., 64, Part II, 15-22, 1907. ScHOEBL, J. Die Fortpflanzung Isopoder Crustaceen. Archiv f. Naturgeschichte, 17, 125-40, 1880. VAN NAME, WILLARD G. The American land and fresh-water crustacea. Bull. A mer. Mus. Nat. Hst., 71, 1936. (535 pp.) VERHOEFF, K. W. Ueber mediterrane Oniscoideen, namentlich Porcellioniden. Jah .. reshefte d.Ver. f. vaterl. Naturk. in Wurttemberg, 73, 144-73, 1917. [pp. 167-68.] ----,Zur Kenntnis der Landasseln Palastinas. 30. Isopoden-Aufsa:tz. Archiv f. Naturgeschichte, 89, 206-31, 1923. [p. 225.] TABLE I DISTRIBUTION OF SAMPLE POPULATIONS OF Porcellio quadriseriatus IN DIFFERENT SIZE-CLASSES, (by percents) Length (mm.) 3 4 5 6 7 8 9 10 Ave.L. 15 My-1 Je '32 Males (100) Females (100) 4-14 Je '36 Males (100) Females (100) 4-14 JI '36 Males (100) Females (100) 1 1 2 10 31 40 10 14 20 20 50 41 28 38 43 48 17 12 27 28 27 21 1 6 TABLE II 26 18 8 1 1 6 SIZE OF MARSUPIAL BROODS OF Porcellio Date No. of Females Size* of Females Range Average 15 My-1 Je 45 5.0-8.1 6.3 19~2 4-14Je 31 4.3-7.0 5.4 1936 4-14 JI 17 4.3-5.4 4.45 1936 11S1936 32 3.3-5.5 4.0 (*) in miBimeters. 1 1 6.196 mm. 5.728 5.489 5.099 ? ? quadrfaeriatus Brood Size Range Average Median 6-28 13.6 13 4-16 9.3 9 3-13 6.5 6 1-10 4.6 5 166 FIELD AND LABORATORY [Vol. 19 TABLE III TABULAR VIEW,FOR45 FEMAiEs-(15 May-1 June,1932), WITH , NUMBERS OF YOUNG CONTAINED IN 1:HEIR MARSUPIA . mm. .o .1 .2 • 3 .4 .5 .6 .7 .8 .9 4 6, 9 9 9, 11 12, 16 9, 11 5 16 9, 9, 10 14, 14 13, 13 12 11, 12 16, 16 11, 12 6 13, 13 14, 14 11, 13 7 14, 15 14, 15 17, 18 16, 18 16, 18 19, 20, 22 8 28 TABLE IV SEX-AND LENGTH-DATA OF A POPULATION OF 1015 Porcellio quadriseriatus COLLECTED AT DALLAS, JUNE 4-14, 1936. Length (mm.) 2 3 4 5 6 7 8 Males 22 227 111 17 19 4 0 Females 8 113 308 1 79 29 1 0 Total 377 638 Two New Texas Species of Physostegia (Labiatae) , Lloyd H. Shinners PHYSOSTEGIA praemorsa Shinners, sp. nov. Perennis arrhizomatosa caule glabro 25-55 cm. alto, foliis anguste oblongis vel oblongo-oblance-olatis glabris acutis acute serratis ca. 2.5-7 cm. longis 0.5-1.2 cm. latis; inflorescentiae parte superiore cum bracteis calycibusque dense pubes-· cente parce glandulosa; corolla 2.2-3 cm. longa; nuculis glabris 4 mm. longis. Perennial by basal offsets, without rhizomes, but with numerous fleshy fibrous roots. Stem glabrous, 25-55 cm. high; internodes 1-3 cm. long. Leaves glabrous, subsucculent, narrowly oblong or oblong-oblanceolate, acute, sharply and rather closely serrate except in basal 1/4 or ½ with teeth directed· forward, sessile or the lower with slight narrowed petiolar base; blades of middle stem leaves 2.5-7 cm. long by 0.5-1.2 cm. wide; upper leaves slightly reduced, passing abruptly into the small leafy bracts of the inflorescence. Inflorescence a simple ' spike-like raceme, with flowers about 3-5 cm. apart; upper part of inflorescence, bracts, and calyxes finely and densel~ pubescent with whitish erect hairs 0.1 mm. long, with scattered gland-tipped hairs of the same length. Bracts oblong-lanceolate or narrowly ovate-lanceolate, those near middle of inflorescence 3-5 mm. long. Pedicels at first scarcely evident, becoming as much as 2.5 mm. long in fruit. Calyx asymmetrically funnelform, 6-7 mm. long (the ovate-lanceolate teeth 1-2 mm. long) in flower, up to 10 mm. (teeth 2.5 mm.) in fruit. Corolla 2.2-3 cm. long, finely puberulent without (less densely so than the calyx), light violet toward base, nearly white with violet dots toward mouth. Nutlets 4, glabrous, black-brown, 4 mm. long, asym-metrically 3-sided with sharp angles, dorsally convex and 2.5 mm. wide, the two ventrar' faces unequal, concave. TYPE: chalk outcrop,.-

Porcellio quadriseriatus (Isopoda) at Dallas, Texas

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Porcellio quadriseriatus (Isopoda) at Dallas, Texas

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