William A. Shear.
The Milliped Family Rhiscosomididae (Diplopoda: Chordeumida: Striarioidea).
Psyche 80:189-203, 1973.

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THE MILLIPED FAMILY RHISCOSOMIDIDAE
( DIPLOPODA : CHORDEUMIDA : STRIARIOIDEA) * BY WILLIAM A. SHEAR
Department of Zoology, University of Florida, Gainesville, Florida 32601
Silvestri (1909) established the Family Rhiscosomididae for the single species Rhiscosomides mineri, from Oregon. Aside from the description of a second Oregon species by Chamberlin (R. josephi) from a female (Charnberlin, 1941), nothing further had been learned about the relationships or ecology of the millipeds of the family until my general review (Shear, 1972) of the North Ameri- can families of the Order Chordeumida. In that paper, I described a third species, R. acov,escor, from California, transferred Tingupa monterea Chamberlin to Rhiscosomides, and established the relation- ship of the Family Rhiscosomididae to the Families Caseyidae, Uro- chordeumidae and Striariidae. Together, these four families make up the Superfamily Striarioidea.
Beginning in late 1971, I received nearly 600 unsorted Berlese samples from Ellen M. Benedict, of the Department of Biology, Portland State University, Portland, Oregon, and about 50 similar samples from Dr. David Malcolm, Pacific University, Forest Grove, Oregon. These samples were taken pursuant to studies of pseudo- scorpions, but also contained a large number of millipeds. The milli- peds from this material add enormously to our knowledge of the fauna of the northern Pacific coast of the United States, and I am extremely grateful to Mrs. Benedict and Dr. Malcolm for allowing me to examine them. This paper represents the first report based largely on the Oregon Berlese material, which now allows a more or less comprehensive revision of several little-known milliped fam- ilies. I am also grateful to Dr. Paul Arnaud, California Academy of Sciences, San Francisco, California, for allowing me to borrow that institution's collection of unidentified millipeds. However, despite the rich material now available, a number of questions remain to be answered concerning the rhiscosomidids. ( i ) Charnberlin's species R. montereurn, the southernmost known representative of the genus, remains unstudied, since the types (the only known material) are no longer in existence. It appears to be a species distinct from R. acovescor, of Marin County. (2) The re- *Manuscript received by the editor Jdy 5.1973



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190 Psyche
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lationship of the rhiscosomidids to the striariids is even more obvious than before. I think that when the striariids from the Benedict and Malcolm collections are thoroughly studied, it might prove desirable to even consider the Rhiscosomididae a subfamily of the Striariidae, despite the numerous differences in gross body form. (3) More material from California is needed, as there are probably several additional species occurring there. (4) Rhiscosomidids have not been collected in the state of Washington, where they may also occur, though numbers of Berlese samples from suitable habitats in that state contained no rhiscosomidids. The southern coastal region of Washington needs further exploration for millipeds. Ecologically, there do not appear to be any really significant dif- ferences in the habitats of the several known species. All have been collected most frequently from rotted wood, from conifer duff, and less frequently from deciduous duff and litter. Collections where elevational data is available are from I 100 ft. elevation or less. Nearly all were taken between November and March. However, the holotypes of R. montereurn and R. trinitarium were collected in June and July respectively, and the latter was taken above 3400 ft. elevation. It should be emphasized that this data represents negative evidence from many samples from suitable habitats taken by Mrs. Benedict at much higher elevations and at other times of the year. Summer and early fall samples were poor in all types of millipeds; perhaps we are dealing here with a fauna adapted to low to moderate temperatures and high humidity, individuals of which burrow deeper into the soil during unfavorable seasons. All type material for new species described below has been de- posited in the Museum of Comparative Zoology, Cambridge, Massa- chusetts, except for the holotype of R. trinitarium, which is the property of the California Academy of Sciences, San Francisco,
California.
Family Rhiscosomididae Silvestri
Rhiscosomididae Silvestri, 1909, Rend. R. Accad,. Lincei 18: 232; 1913, Boll. Lab. 2001. Portici 7: 307; Shear, 1972, Bull. Mus. Comp. 2001. 144 (4) : 261.
Type Genus: Rhisoosomides Silvestri, 1909. The family is mono- basic.
Diagnosis:
Distinct from species of Caseyidae in having broad segmental paranota, from species of Urochordeumidae in having the collum wider than the head, and from species of Striariidae in the



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19731 Shear - Rhiscosomididae 191
body ornamentation (Fig. 4) : tiny, sharp, seta-tipped tubercles, rather than longitudinal ridges. Rhiscosomidids also resemble some- what the larger species of the genus
Tingupa (Tingupidae), but
may be distinguished from them by the body ornamentation as well; tingupids are covered with short, longitudinal carinae. Description: Small, striarioid millipeds (Fig. 4) with 30 post- cephalic segments. Collum broader than head, only slightly reflexed ventrad laterally. Antennae clavate, short. Mentum of gnathochi- larium divided. Postcollum segments with strong paranoia extending laterad, posterior lateral corners becoming strongly reflexed posteriad, segmental setae long, rather blunt. Surfaces of metazonites covered with closely set, sharply pointed tubercles bearing tiny branched setae. Sixth segment of males enlarged in some species. Epiproct trilobed. Legs normal, pregonopodal legs of males somewhat more crassate than postgonopodal legs. Gonopods of males (Figs. 2, 7, 10, 18) with sternum strongly sclerotized, two prominent groups of coxal processes. Anterior coxal processes partially fused in some species to form anterior plate. Posterior coxal processes usually fur- nished with fimbriate, membranous, or flagelliform branches and areas. Telopodites irregular, lobelike. Ninth legs reduced in size, with blunt coxal process, flattened, granular telopodite o'f one seg- ment (Figs. 9, I 4, I 6). Coxae of legs 10 with glands opening on anterior faces. Legs I I normal. Cyphopods embraced by expansions of sternites and coxae of second and third legs, with postgenital structures of uncertain origin (Fig. 3). Distribution: Pacific coast region of the United States from the Monterey Penninsula north to the Columbia River, usually at ele- vations below I 100 ft.
Genus R hiscosomides Silvestri
Rhiscosomides Silvestri, 1909, Rend. R. Accad. Lincei 18: 232; 1919, Bull. Lab. 2001. Portici 7: 308; Shear, 1972, Bull. Mus. Comp 2001. 144(4) : 261. Type Species: Rhiscosomides mineri Silvestri, by monotypy. Description: The genus and family are coextensive, but the fol- lowing additional characters may be noted. Body generally dark brown in color, collum usually cream-white, bases of segmental setae marked with light spots. In species in which sixth segment of males is enlarged, that segment lighter in color dorsally than the others. General appearance is of parallel-sided polydesmiform animals, squared off anteriorly at collum, tapering abruptly to blunt epiproct from segment 25. Ocelli vary in number from 5 to 7, variable within species.




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192 Psyche [September
Gonopod Anatomy of Rhiscosomides Species The gonopods of Rhiscosomides species males conform well to the striarioid pattern. The sternum (Fig, 2, 5) is heavily sclerotized and anteriorly margined, with deeply depressed openings from the tracheal spiracles. Laterally, the sternum is broadly expanded, con- cealing the bases of the coxal processes. The anterior coxal processes (Fig. I, AC) are closely appressed, and in the Acovescor Group of species are wholly or partially fused to form a broad plate. A strong lateral branch is usually present (Fig. 2, LB), but may be a broad flange (Fig, 7), or the largest part of the process (Fig. 18). The length of the anterior coxal process and the form of its terminal branches are of excellent taxonomic and diagnostic value. The pos- terior coxal process usually has three branches: the anterior branch (Fig. 7, AB) , the mesa] branch (Fig. 7, MB), usually the largest, and die generally much smaller posterior branch (Fig. 7, PB) , The mesa! and posterior branches are usually connected by a membranous or fimbriate area. There is also a flabellifom median structure arising from the heavily sclerotized part of the sternum that extends between the gonopods. This sterna! flap (Fig. 10, SF) usually comes off with one or the other of the gonopods when they are sep- arated. The telopodites (Figs. 2, 10, T) are amorphous, lobelike structures that are usually displaced laterally, but may interlock basally with the lateral extensions of the sternum or of the anterior coxal processes. They are of little taxonomic value. The posterior gonopods are rather uniform throughout the genus (Figs. 9, 14, 16). In my 1972 description, I erred in calling the narrow anterior mesa1 coxal lobe the telopodite. The actual telopodite is flattened and irregular in outline and bears a more or less pointed process on the posteriomesal margin, which extends posteriad. This telopodite pro- cess and the coxai lobe protect and partially support the anterior gonopods, and in some animals, clasp between them the coxae of legs 10,
In terms of gonopod anatomy and a few other characters, the six species known from males fall into two groups. In the Acovescor Group (R. acovescor, R. trinitmium), the anterior coxal processes tend to be fused or broadly contiguous mesally, and are rather short. Areas of highly branched, fine cuticular fibers are well developed on the posterior coxal processes. The sixth segment of the males is only slightly or not at all enlarged; in R. acovescor the collum is colored like the other segments, instead of being white. Females have not been collected.
Both species occur in California, and R. montereurn will probably also prove to belong to the group.



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19731 Shear - Rhiscosomididae I93
The Miner! Group includes R. mineri, R. josephi, R. malcolmi and R. benedictae. In these species, the anterior coxal processes are usually more rodlike, not at all fused mesally, and are more or less sharply curved anteriad. The fimbriate or membranous areas on the posterior coxal processes are of limited extent, and there is an area on the mesa1 branch that appears to be glandular. The sixth segment of males is enlarged; the collum is white. Females have postgenital bodies (Fig. 3) of uncertain origin immediately posterior to the cyphopods. These are of limited utility in diagnosis, though they cannot be used to separate some species. The four species occur
along the Oregon coast and in the foothills of the Coast Ranges. Certainly, by the standards that have been applied in the past, these two species groups might have been recognized as genera, and I suggested (Shear, 1972) that R. acovescor might not be congeneric with R. mineri. However, R. mineri, the type species of Rhiscoso- mides, shows a degree of intermediacy in the form of the anterior coxal processes, particularly when compared to R. triniturium, which, in turn, is intermediate between R. mineri and R. acovescor. In the light of these facts, and because of the small number of species in the
I a.
I b.
2 a.
2b.
3a*
3b.
4a*
4b.
family, it seems pointless to recognize a second genus at this time. Key to Species of Rhiscosomides
(excluding R. montereum)
Sixth segment of males conspicuously enlarged (Fig. 4)) lighter in color than other segments; anterior coxal processes of gono- pods usually rather rodlike (Figs. 7, 10, 15)) touching mesally but not fused. .............................................................................. 3 Sixth segment of males not much larger, if at all, than other segments; anterior coxal processes of gonopods som'ewhat flat- tened to platelike, more or less contiguous mesally, or fused. 2 Anterior coxal processes without lateral branches, fused into a ....................
broad plate (Fig. 17) ; Marin Co., Calif. acovescor
Anterior coxal processes with elaborate bra,nches; Trinity Co., ............................................................................ Calif. triniturium
Apical teeth or processes of anterior coxal process small, not directed posteriad (Figs. 7, 10, 15). ...................................... 4 Anterior coxal process with large apical branch directed ventro- .............................................................. posteriad (Fig. 2) mineri
Anterior coxal processes bent sh,arply anteriad at nearly a right angle (Figs. 7, I 5) .................................................................... 5 Anterior coxal processes long, rodlike, evenly curved (Fig. 10) ........................................................................................ benedictae



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194 Psyche [September
5a. Anterior branch of posterior coxal process broad, bladelike (Fig. I 5 ) .................................................................................. malcolmi 5b. Anterior branch of posterior coxal process narrow, more rod- like (Fig. 7) ...................................................................... josephi Rhiscosomides montercum (Chamberlin)
Tingupa monterea Chamberlin, 1910, Ann. Ent. Soc. Amer. 3: 240-241, figs. 3-5, sex not specified.
Rhiscosomides monterea, Shear, 1972, Bull. Mus. Comp. 2001. 144(4) : 262. Type: Holotype of unspecified sex from Pacific Grove, California, collected June, 1902, lost, presumed destroyed. Notes: Little more can be said about this form until males arc discovered, but as I earlier pointed out (Shear, 1972), the detailed description of the nonsexual characters leaves no doubt that this species belongs to Rhiscosomides and not to Tingupa. There are
eight ocelli. An immature Rhisoosomides female from San Mateo
County, California, also has eight ocelli, and may be an example of R. montereum.
The change in spelling of the specific epithet, which I did not ob- serve in my 1972 report, is made necessary by the gender of the generic name.
R hiscosomides mineri Silvestri
Figs. 1-3
Rhiscosomides miner; Silvestri, 1913, Boll. Lab. 2001. Portici 7: 308-310, figs. 4-7, 8 ; Shear, 1972, Bull. Mus. Comp. Zool. 1,41(4) : 261-262. Type: Male holotype from a rotting log, Lebanon, Linn Co., Oregon; whereabout of specimen unknown, not examined. Silvestri's excellent figures (Silvestri, 1913 ) leave no doubt about the identity of this species.
Description: Male from 5 mi east of Yamhill, Yamhill Co., Ore- gon; length, 7.1 mm, width, 1.12 mm. Body of typical form, head broad, front somewhat flattened, depressed in anterior midline, su- prantennal swellings moderate. Antennae short, strongly clavate, reflexed along sides of head, reaching anterior margin of segment 4 when fully extended. Ocelli seven, in two rows of three and four. Collum broader than head, lateral margins only a little deflexed ventrad,
posteriolateral corners rounded, curved anteriad, anterior margin sinuous, posterior margin arcuate. Segments with rather narrow, polydesmiform paranota at first curved forward, posterio- lateral corners becoming acute, reflexed posteriad, anterior and pos-



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Shear - Rhiscosomididae
Figs. 1-3. Rhiscosomides mineri. Fig. 1. Anterior coxal processes of anterior gonopods, anterior view. Fig. 2. Right anterior gonopod, lateral view. Fig. 3. Cyphopods, posterior view. Figs. 4-6. R. josephi. Fig. 4. Body of male, lateral view of anterior end. Fig. 5. Sternum and coxae of
legs 2 of female, posterior view. Fig. 6. Left postgenital structure of female, posterior view.




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196 Psyche [September
terior margins of paranota evenly curved. Prozonites of segments with small, rounded granules becoming larger, acute on metazonites, bearing minute branched setae. Segmental setae along anterior mar- gin of metazonite, outermost at midpoint in lateral margins of para- nota. Epiproct trilobed. Legs short, femora clavate. Legs 7 with c0xa.e somewhat enlarged. Anterior gonopods (Figs. I, 2) typical. Anterior coxal processes closely appressed in midline (Fig. I), with large posteriorly directed apical branch (Fig. 2), blunt, spatulate lateral branch embracing posterior coxal process. Anterior branch of posterior coxal process long, acute, curved, sword- like; mesa1 branch nea.rly sigmoid, conforming to lateral branch of anterior coxal process; posterior branch apparently absent. Telo- podite lobelike. Posterior gonopod (ninth leg) typical, flattened, setose. 'Coxae of legs 10 enlarged, gland opening on anterior face. Other postgonopodal legs normal.
Coloration: dark brown, prozonites and metazonites of sixth seg- ment lighter tan, collum cream-white, legs and venter white. Bases of segmental setae marked by light spots. Female from same locality: Size and body form much as in male, but sixth segment of normal size. Ocelli of 3 females: 2 specimens have 5 ocelli, one has 6. Cyphopods and postgenital structures as in Fig. 3.
Distribution: OREGON: Yamhill Co., 5 mi east of Yamhill on Hwy 240, Berlese of litter and grass, 2 October 1971, E. Benedict, 8 9 9 ; Washington Co., 2 mi north of Helvetia on Bishop Road, Berlese of mixed conifer and deciduous duff, 21 January 1968, D. Malcolm, Q; Tillamook Go., 4 mi south of Blaine, elev. 500', Berlese of rotten wood, 15 March 1972, E. Benedict, Q.
Rhiscosomtdes josephi Chamberlin
Figs. 4-9
Rhiscosomides josephi Chamberlin, 1941, Bull. Univ. Utah Biol. Ser. 6: 16-17, no figs. ; Shear, 1972, Bull. Mus. Comp. 2001. 141 (4) : 262. Type: Female holotype from "John Day Creek," Douglas Co., Oregon, collected 18 November 1941, by J. C. Chamberlin ; speci- men in Chamberlin Collection, now at U. S. National Museum. There is no "John Day Creek" in Douglas Co., but there is a town of Day Creek, and a small stream of that name flowing into the, South Umpqua River. It is presumed that this is the type locality, and not the region of the John Day River to the northeast, semiarid country from which few milli~eds have been collected. All subse-



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19731 Shear - R hiscosomididae I97
quent collections of R. josephi are from the Douglas Co. region. Admittedly, the assignment of this species name is somewhat arbi- trary, but no harm is done by using it for the commonest species of southwestern Oregon.
Description: Male from Canyonville County Park, Douglas Co., Oregon; length, 7.0 mm, width, 1.10 mm. Body of typical form, nonsexual characters as described for R. mineri. Anterior gonopods
(Figs. 7, 8) : anterior coxal processes short, sharply curved anteriad, termination complex, somewhat variable (compare Figs. 7 and 8), usually with large lateral tooth, smaller mesal teeth, small anterior tooth; lateral branch of process a broad flange embracing posterior coxal processes. Posterior coxal processes with anterior and mesal branches bent sharply posteriad at right angles, posterior branch much reduced. Telopodites typical. Ninth legs (posterior gonopods) typical of genus (Fig. 9). Coloration as usual.
Female from same locality; size and structure much as in male, sixth segment not enlarged. Sternite of second legs with blunt exten- sion between coxae (Fig. 5), postgenital structure similar to that of R. mineri (Fig. 6).
Distribution: OREGON: Ooos Co., 8 mi east, 2 mi south of Allc- gany, Weyerhauser Co. Millicoma Tree Farm, company road 5000, Berlese of Pseudotsuga bark flakes on clear-cut slope, 20 November 1971, E. M. Benedict, 9 ; Curry Co., 13 mi east of Gold Beach on road to Agness, elev. 600', Berlese of tan oak duff, 10 March 1972, E. M. Benedict,
5 9 9 ; Douglas Co., Canyonville County Park, 2 mi east of Canyonville off Rt. 227, Berlese of duff, moss, wood, soil, elev. 1000', 6 November 1971, E. M. Benedict, c? 2 mi north of Melrose, elev. 400' berlese of rotted wood and duff, 7 February 1972, E. M. Benedict, 5, 0.7 mi west of Scottsbui-g, near Umpqua River, elev. 300', Berlese of rotted myrtle heartwood, I I December 1971, E. M. Benedict, 5 9, Elliot State Forest, I mi south, 2 mi west of Ash, elev. I IOO', Berlese of mixed duff from conifers, bigleaf maples, I I December 197 I, E. M. Benedict, 9, 2 mi southeast of Day Creek on Rt. 227, elev. IOOO', berlese of oak and madrone litter, 6 November 197 I, E. M. Benedict, 8 . Notes: Fig. 8, of the male from 2 mi southeast of Day Creek, and Fig. 7, of the described male from Canyonville County Park, though fairly close geographically, represent the extremes of variation in the termination of the anterior coxal process. Females are difficult to distinguish, except by locality (see Map I ) from those of R. mineri, as the postgenital structures are very similar (cf. Figs. 3 and 6).



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198 Psyche
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Figs. 7-9. Rhiscosomides josephl. Fig. 7. Right anterior gonopod, lateral view.
Fig. 8. Termination of gonopod of variant specimen, lateral view. Fig. 9. Left posterior gonopod, anterior view. Figs. 10-13. R. benedictae, Fig. 10. Right anterior gonopod, lateral view. Fig. 11. Termination of gonopod of variant specimen, lateral view. Fig. 12. Sternum and coxae of
legs 2 of female, posterior view. Fig. 13. Left cyphopod and postgenital structure, posterior view.




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Shear - Rhiscosomididae
Map 1.
Coastal Oregon, showing distribution of species of Rhiscosomides. lots, R. mineri. Squares, R. josephi. Triangles, R. benedictae. Circles, R. nalcolmi.




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Rhiscosomides benedictae n. sp.
Figs. 10-14
Types: Male holotype and female paratype from woods behind Marine Biological Institute, Charleston, Coos Co., Oregon, col- lected from a Berlese sample of spruce, alder and cedax duff by E. M. Benedict, 30 April 1967.
Description: Male holotype; size and nonsexual characters as described for R. mineri.
Anterior gonopods: anterior coxal processes long (Fig. IO), slightly curved, terminating in lateral and dorsal teeth and blunt mesal lobe; lateral branch small lamella. Posterior coxal processes with anterior branch small, rodlike, mesal branch upright, of mod- erate size, posterior branch relatively large, membranous anterior face. Telopodites lobed, interlocking with lateral extensions of an- terior coxal processes. Ninth legs (Fig. 14) of usual form. Female paratype typical of genus; process from second sternite (Fig. 12) thin, postgenital structures as in Fig. 13. Distribution: OREGON: Lincoln Co., State Forest Camp east of Waldport, 30 October 1960, D. R. Malcolm, 8 ; Blenton Co., Rt. 34 at Benton Co. line, Berlese of maple and alder duff, 30 October 1960, Malcolm, 8 8 9 9 ; Daouglas Co., 3.2 mi northeast of Scotts- burg, elev. 4001, Berlese of rotted wood and bark, 11 December
1971, E. M. Benedict, d?$; Coos Co., 4 mi east, 2 mi south of Allegany, Weyerhauser Co. Millicoma Tree Farm, company road 6000, Berlese of rotted wood from riparian zone of Fall Creek, between steep canyon walls, 21 November 1971, E. M. Benedict, 8899.
Notes: Fig. I I illustrates a slight variation in the form of the termination of the anterior coxal process of the anterior gonopod of the Benton Co. specimen. Those from the Millicoma Tree Farm are similar to this; at that place R. benedictae is nearly syntopic with R. josephi, which was taken from bark chips on a clear-cut slope, while R.
benedictae was taken from litter in a riparian zone. It would be interesting to further explore the ecological situation be- tween these two species.
Rhiscosomides malcolmi n. sp.
Figs. 15, 16
Types: Male holotype, female paratypes from 13 mi north, 5 mi west of Brookings, Curry Co., Oregon, collected 10 March 1972