A new crawfish of the genus Orconectes from the Yazoo River system of Mississippi (Decapoda: Cambaridae)

7 Pages·1992·4.7 MB·English

PROC. BIOL. SOC. WASH.
105(1), 1992, pp. 70-76
A NEW CRAWFISH OF THE GENUS ORCONECTES FROM
THE YAZOO RIVER SYSTEM OF MISSISSIPPI
(DECAPODA: CAMBARIDAE)
J. F. Fitzpatrick, Jr. and Royal D. Suttkus
—
Abstract. Thecrawfish Orconectes(Hespericambarus) hartfieldi, isdescribed
from five sites in the Yazoo River system ofMississippi. It is distinguished by
a notch near the apex of the central projection of the first pleopod of the first
form male, and the annulus ventralis of the female is the most sculptured in
the subgenus. Its closest relatives seem to be O. (H.) hathawayi Penn and O.
{H.) perfectus Walls; geographically, it is distributed between the ranges ofthe
two.
Most of the populations of members of sin and many were at his disposal, he
the crawfish genus Orconectes that occur in expressly limited his paratypic series to a
the Big Black, Tombigbee, and Yazoo sys- few populations in the immediate vicinity
tems of Mississippi currently are not as- of the type locality. Recently, one of us
signed trivial names. Most of them, nev- (RDS) collected first form males and other
ertheless, can be relegated to the subgenus specimens assignable to this subgenus from
Gremicambarus (Fitzpatrick, 1987), but four widely spaced localities in the Yazoo
otherwise they are so similar in morphology basin. The first pleopod ofthe Form I male
that it is difficult to separate one interbreed- and the annulus ventralis ofthe female are
ing group from another. This was recog- sufficiently distinctive that we are secure in
nized by Cooper & Hobbs (1980:1) when our belief that these populations represent
they observed: "Unfortunately, without first a previously undescribed species. Further,
form males, we have been unable to identify the geographic dispersal, enhanced by an-
specimens in the genus from many localities other single Form I male collected in 1967
in the Mobile and Tennessee basins." They from yet another distant locality, precludes
emphasized the need for knowledge of the the possibility that the specimens are local
precise limits of variation in the non-sec- or abnormal variants.
ondary sexual characters. Otherwise, only
the morphology ofthe first pleopod ofForm Orconectes {Hespericambarus) hartfieldi,
new species
I males is reliable for the identification of
species. We can add that even the character Fig. 1
states of non-sexual features, without good Diagnosis. —Pigmented; eyes normal.
series for comparison, can be misleading. Rostrum with slightly thickened, somewhat
We
can likewise include the Big Black and converging margins ending cephalically in
Yazoo basins in systems inhabited by such small acute spines; lacking median carina;
populations. acumen distinct, moderately long, and
When Walls (1972) described Orconectes clearly delimited basally from remainder of
{Hespericambarus)perfectus, he implied that rostrum. Areola obliterated for most of
similar situations exist in this subgenus. Al- length and comprising 31.9 to 35.2% (avg.
though morphologically similar popula- 33.3%) oftotal carapace length, and 44. 1 to
tions occur throughout the Tombigbee ba- 47.6% (avg. 45.7%) of postorbital carapace
VOLUME NUMBER
105, 1 71
length. Cervical spine prominent; suborbit- orbital length). Rostrum with margins little
al angle absent; postorbital ridge well de- thickened, elevated, slightly convergent, and
veloped and terminating cephalically in bearing small but acute spines at base of
strong acute spine. Antennal scale usually clearly delineated acumen, latter almost
2.06 times longer than wide and widest reaching distal end ofantennular peduncle;
slightly distal to midlength. Chelae ofadult upper surface slightly concave, lacking me-
males inflated, slightly costate laterally at dian carina, and only sparsely punctate ex-
best, and covered by numerous setae oc- cept for row flanking elevated margins me-
curring in loose tufts originating in shallow sially. Subrostral ridge weak, disappearing
punctations; mesial margin with 3 to 7 small in dorsal aspect before reaching base ofros-
to moderate-sized acute spines or spiniform trum. Postorbital ridge heavy, with dorso-
tubercles; tubercles extending onto basal half lateral and dorsomesial grooves, terminat-
of mesial margin of dactyl in varying de- ing cephalically in strong acute spine.
grees of development and number, often Suborbital angle absent. Cervical spine sin-
with squamous or low spiniform tubercles gle, strong, and acute; branchiostegal spine
flanking mesial row ofspines above and be- well developed. Carapace studded with
low; opposable margins ofboth fingers with shallow setose punctations developing into
small tubercles in basal halfand slightly ir- granulose tubercles ventrolaterally. Abdo-
regular band of minute denticles in distal men shorter than carapace (22.8 and 23.7
half; both fingers with weakly developed mm); pleura well developed and rounded
longitudinal ridges flanked by scant setose ventrally except that of second abdominal
punctations above and below. Hook on is- segment, which subtruncate; cephalic sec-
chium ofthird pereiopod only, not opposed tion of telson with 2 spines in each caudo-
by tubercle on corresponding basis; coxae lateral corner, more mesial ones movable.
ofpereiopods lacking boss. First pleopod of Proximal podomere of uropod with acute
first form male reaching coxae of third pe- spine on mesial lobe only; mesial ramus with
reiopod when abdomen flexed, lacking distinct but weakly developed dorsomedian
shoulder on cephalic surface, terminating in keel terminating in small premarginal spine;
two elements, both inclined caudodistally; lateral ramus likewise keeled.
central projection longer and with slight Cephalic lobe ofepistome (Fig. In) lack-
subapical notch or shallow depression cau- ing cephalomedian projection and delim-
dodistally; mesial process non-corneous, ited basally by distinctly contracted base;
only slightly curved, tapering smoothly to margins elevated with distinct notch (?old
subacute apex and directed caudomesially injury) on left side; cephalic lobe excavate
at about 45° angle to main shaft ofappend- with prominent longitudinal median ridge
age. Annulus ventralis offemale as figured. rising (ventrally) as high as margins; main
First pleopod present in female. body with deep, pit-like fovea; epistomal
—
Holotypic male, Form I. Body and eyes zygoma broadly arched. Basal segment of
pigmented. Cephalothorax (Figs, lb, 1) sub- antennule with small spine on ventral sur-
ovate in section, abdomen narrower than face slightly distal to midlength. Antennae
carapace (10.1 and 11.2 mm), width oflatter almost reaching caudal margin of fifth ab-
greater than depth at caudodorsal margin of dominal segment. Antennal scale (Fig. Ik)
cervical groove (1 1.2 and 10.5 mm). Areola 2.24 times as long as broad with greatest
obliterated for most of length with usual width slightly distal to midlength; mesial
subtriangular cephalic part and weakly de- border of lamella rounded but less than
veloped divergent margins in caudal fifth of evenly so; apical spine strong and reaching
thoracic portion of carapace; length 33.3% just beyond distal margin of ultimate pod-
of total length of carapace (45.9% of post- omere of antennal peduncle.
72 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Right chela (Fig. lm) depressed, weakly vation ofcentral projection shallow, not dis-
costate laterally only along basal halfofim- tinct notch.
movable finger, 2. 1 times longerthan broad; Allotypic female.—Differing from holo-
all surfaces pubescent. Mesial margin of type, except in secondary sexual character-
palm with row of 4 spiniform tubercles, istics, in followingrespects: abdomen longer
somewhat obscured by pubesence and 1 than carapace (3 1.0 and 28. 1 mm) and only
rounded tubercle proximally; 2 small tu- slightly narrower than carapace (12.8 and
bercles on mesial margin ofdactyl near base 13.0 mm). Mesial margin of palm with 5
obscured by pubesence. Fingers not gaping. spinose tubercles; distalmost tubercles of
Opposable margin of fixed finger with row mesial margin ofcarpus much more spine-
of 6 tubercles in basal half and band of like and acute than others; lower lateral
crowded minute denticles extendingdistally margin of merus with 4 tubercles and dis-
from penultimate tubercle ofgroup, denti- tally one low spiniform tubercle followed
cles interrupted halfway to tip of finger by by ultimate strong spiniform tubercle.
another small tubercle; additional tubercles Annulus ventralis (Fig. le) as illustrated;
ventral to aforementioned dentition at base sinus originating lateral to midline in deep
offingerand atbase ofdistal fourth offinger; posteromesially inclined sulcus in cephalic
all tubercles and denticles obscured by third ofannulus, continuing across midline
pubesence. Opposable margin ofdactyl with before turning caudally to anterior border
4 subequal tubercles in basal halfand band of caudal third of annulus, there turning
of crowded minute denticles extending to sharply to midline and thence recurving to
apex offinger, large tubercle ventral to row followgently sinuous path to caudal margin.
at base of finger; all tubercles and denticles Postannular sclerite about half as wide as
obscured by pubesence. Carpus about 1.2 annulus and just over three times as broad
times longerthan broad, with archedgroove as long. First pleopods small but distinct.
dorsally, latrer flanked mesially by few low Morphotypic male, Form //.—Differing
tubercles and laterally by scarce, very shal- from holotype in following respects: mesial
low punctations; mesial surface with spike- margin ofpalm with row of3 low tubercles;
like tubercle distal to midlength andbroadly mesial margin ofcarpus more like allotype
triangular one subdistally; ventral surface than holotype; conspicuous gap between ul-
with spiniform tubercle in mesiodistal and timate and penultimate spiniform tubercles
laterodistal corners. Dorsal surface ofmerus oflower mesial margin ofmerus, lower lat-
with 2 stout spines distally; lateral and me- eral margin with row of 7 low tubercles
sial surfaces with scarce, shallow puncta- proximally and distalmost two spiniform
tions; lower lateral margin with row of 8 similar to those ofallotype. Hook on ischi-
um
small tubercles terminating distally in of third pereiopod weakly developed,
prominent spiniform one; lower lateral not overreaching distal margin of corre-
margin with evenly spaced row of 3 spini- sponding basis. Cephalic lobe of epistome
form tubercles in distal half. Basis, ischium, weakly excavate, lacking median longitu-
and coxa with margins entire. Ischium of dinal ridge; fovea ofmain body correspond-
only third pereiopod with simple strong ing more shallow.
hook (Fig. lj), latter overreaching distal Color. —Color notes are available for the
margin of corresponding basis but unop- Panola County specimen. Base color olive
posed by tubercle. tan diffused with darker brown and blue-
First pleopods symmetrical, reaching black pigments. Rostral margins light; large
coxae of third pereiopods when abdomen irregular tan spot just posterior to caudal
flexed. First pleopods (Fig. la, c, g-i) as de- extremity of postorbital ridge. Density of
scribed in "Diagnosis"; subterminal exca- dark pigment increasing dorsally so that
VOLUME NUMBER
105, 1 73
Fig.1. Orconectes(Hespericambarus) hartfieldi, new species (all from holotype, exceptdand fofmorphotype
and e of allotype): a, d, Mesial view of first pleopod; b, Lateral view of carapace; c, f, Lateral view of first
pleopod; e, Annulus ventralis; g, Caudal view ofapex offirst pleopod; h, Mesial view ofapex offirst pleopod;
i, Lateral view ofapex offirst pleopod;j, Coxa and ischium ofthird pereiopod; k, Antennal scale; 1, Dorsal view
ofcarapace; m, Dorsal view ofdistal podomeres ofright first cheliped; n, Epistome.
PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
74
ventral half of carapace to about level of section 18, Yalobusha County, Mississippi.
cervical spine pale tan, but dorsal halfdark At this locality, on 23 September 1989, the
brown mottled with small light tan spots. creek was approximately seven to ten me-
Caudodorsal part of thoracic region poste- ters wide; generally shallow, ranging from a
riorto cervical spines lighterwith transverse few centimeters to half a meter in depth;
rows of fine dark spots giving appearance however, in a few places reaching over a
of4 stripes. Cephalic triangular area ofare- meter in depth. The current was slow to
ola nearly filled with blue-black subtrian- moderate and much ofthe sand bottom was
gular spot; irregularly shaped blue-black spot silt-covered. There were numerous snags
just above cervical spine and anterior to with varying amounts of detritus caught
cervical groove; several large blue-black aroundtheirbases. Thewaterwas clearupon
spots at dorsal caudolateral margin of car- arrival at the site but soon became turbid
apace coalescing into large irregular patch from clouds ofsilt that went into suspension
just lateral to posterior flare ofareola. Two because of collecting activities. The water
undulant stripes running longitudinally was 18°C at 1 540 hrwhen the collection was
alonglateral faces ofabdomen such that each made.
segment provided with 2 chevrons, lower at Disposition of types.—The holotype, al-
junction ofpleuron and tergum darker and lotype, and morphotype (USNM 220651,
thinner; pleurons and area between chev- 220652, and 220653, respectively) are de-
rons with numerous dark spots of varying posited in the National Museum ofNatural
size but always small; middorsal part ofter- History, Smithsonian Institution, as is a sin-
minal segment similarly spotted but spots gle paratypic male, Form I. The remaining
more dense and more regular in size and paratypes (3 SI, 4 9) are in the Tulane Uni-
shape. Telson with thin blue-black line along versity Museum ofNatural History (TU).
lateral margin ofcephalic portion, stripe ex- Range and specimens examined.—The
panding to encompass entire area of cau- species is known from only five localities,
dolateral spines; caudal portion of telson all in the Yazoo River basin in Mississippi:
and both uropods with moderately large Calhoun County: (1) Cowpen Creek at St.
NNE
blue-black spots covering dorsal surface, Rte. 9, 8.6 mi (13.8 km) of Bruce,
more densely distributed laterally. Tl IS, R1W, sec. 29, 1 61, 1 9, coll. 26 Aug
Palm and both fingers of cheliped beige, 1989, R.D.S. (TU 6431); Carroll County:
studded with large blue-black spots above (2) Abiaca Creek at St. Rte 17, 0.3 mi (0.5
that form row between spines of mesial km) S ofBlack Hawk (St. Rte. 430), T17N,
margin ofpalm; carpus likewise spotted, as R3E, sec. 20, 1 61, coll. 27 Sep 1987, R.D.S.
also lateral and mesial margins of merus; (TU 6433); Panola County: (3) Oil Creek,
basis, ischium, and coxa concolorous tan. 1.5 mi (2.4 km) E ofU.S. Hwy. 1-55 on St.
Remaining pereiopods striped with alter- Rte 315, T7S, R6W, sec. 30, 1 31, coll. 10
nating circular bands of beige-brown and Aug 1967, J. F. Payne, W. G. Anding
blue-black, latter formed by coalescing dots (USNM 220654); Tallahatchie County: (4)
of pigment; pattern extending from distal Bellamy Creek, 1 .3 mi (2. 1 km) S ofSt. Rte.
coxa to apex ofdactyl. Basal podomeres of 32 in Charleston, T25N, R2E, sec. 26, 1 9,
antennule and antenna beige with irregular coll. 27 Oct 1989, R.D.S. (TU 6432); Ya-
blue-black stripe on lateral margins; flagella lobusha County: (5) type locality, 1 81 (ho-
No
studded with fine dark spots. records of lotype), 1 611, (morphotype), 1 9 (allotype);
ventral coloration available. 1 61, 2 9 (TU 6438), coll. 23 Sep 1989, R.D.S.
Type locality. —Turkey Creek, about 6 mi Variations. —With so small a type series,
(9.7 km) northeastofCoffeeville, 0.2 mi (0.3 observed variation is slight; most is encom-
km) east of State Route 32; T25N, R7E, passed within the limits expressed in the
VOLUME 105, NUMBER 1 75
descriptions of the types, above. The spec- Table 1.—Measurements (mm) ofOrconectes (Hes-
imens from the type locality seem small by pericambarus) hartfieldi, new species.
comparison with the other available sam-
Holo- Allo- Morpho-
ples. The carapace lengths of the types are type type type
mm
23.7, 28.1 and 18.5 (Table 1), and of Carapace
the topotypic male, Form I, 21.5 mm, those Entire length 23.7 28.1 18.5
ofthe females, 22.2 and 19.5 mm. The car- Postorbital length 17.2 20.6 13.3
apace length of the Panola County male, Width 11.2 13.0 8.8
Form I is 33.2 mm; while those ofthe Cal- Height 10.5 12.7 7.4
houn County specimens are: male, Form I, Areola
35.8; female, 32.8 mm. The greatest vari- Length 7.9 9.2 6.1
ation noted is in the spinose ornamentation Rostrum
of the cheliped. As noted in the diagnosis, Length 7.9 11.0 8.1
the number ofspiniform tubercles along the Width 4.8 5.5 4.1
mesial margin ofthe palm varies from three Antennal scale
to seven; in the morphotype, possibly a ju- Length 6.5 7.1 5.6
venile, they are reduced to small rounded Width 3.4 3.8 2.8
tubercles. Although the pattern of distri- Right chela
bution of the tubercular ornamentation of Length, lateral margin 18.1 18.0 10.1
the lower mesial margin ofthe merus varies Length, palm mesial
slightly, the number is consistently three margin 6.4 5.6 4.6
(except the Panola Co. specimen has what Palm width 8.5 7.5 4.4
Dactyl length 11.2 12.1 6.9
appears to be only the broken stump of a
Abdomen
proximal third spine on the right side); in
contrast, the proximal row of tubercles of Length 22.8 31.0 18.0
Width 10.1 12.8 7.5
the lower lateral margin varies from four to
eight. In one male, Form I, and the smallest
female from the type locality the cephalic
m
lobe of the epistome is nearly planar and varying from 2.4 to 9.2 in width. The
lacks the median ridge; the epistome ofthe entire stream bed was compacted clay as
female from Cowpen Creek is similarly de- wasthe lowerthird ofthe stream bank. There
veloped, but the fovea in the main body is were two ledges in the bed of the stream
m
deep, similar to that of the holotype. Also downstream ofthe bridge with a 0.6 drop
the smallest topotypic female has a bifid into a plunge pool. The ledges were under-
spike-like tubercle near midlength of the cut in a few places and there were some
carpus, and the distal one is acutely spini- broken-off pieces in the plunge pool; some
form. crawfish were collected from beneath these
Environmental notes. —Detailed envi- ledges and in the pool. The flow was mod-
ronmental data are available also for Cow- erate but almost no motion was evident in
pen Creek (site 1, above) and they differ the pools. There were "cow cakes" in the
from those at the type locality. It seems stream. At 1720 hrs the temperature ofthe
worthwhile to note this range of tolerance water was 28°C.
for this species. Associates. —Crawfishes collected with
Cowpen Creek at St. Rte. 9 courses Orconectes (Hespericambarus) hartfieldi at
through a narrow, deep, precipitous ravine, one or more sites were Procambarus (Pen-
and on 26 August 1989, was in low water nides) ouachitae Penn, 1956, Cambarus
stage. The stream bed was estimated to be (Lacunicambarus) sp. ref. ludovicianus, and
m
12.1-15.3 wide with a channel of water an undescribed member of the genus Or-
PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
76
conectes assignable to the subgenus Gremi- for their efforts in securing specimens. Es-
cambarus. pecially we note the constructive criticism
Relationships.—The closest relatives of ofthe manuscript by H. H. Hobbs, Jr.
Orconectes {Hespericambarus) hartfieldi are
O. (//.) hathawayi Penn, 1952 and O. (H.) Literature Cited
perfectus Walls, 1972. First form males of
Cooper, M. R., & H. H. Hobbs, Jr. 1980. New and
O. (H.) hartfieldi are easily separated by the little known crayfishes of the virilis section of
presence of a subapical notch or shallow the genus Orconectes (Decapoda: Cambaridae)
depression on the caudodistal margin ofthe from the southeastern United States.—Smith-
central projection; the notch is suggested on sonian Contributions to Zoology 320:iii + 44
the male, Form II, but it is not so clearly pp.
denned. The annulus ventralis ofthe female Fitzpatrick,J. F.,Jr. 1987. Thesubgeneraofthecraw-
fish genus Orconectes (Decapoda: Cambari-
is the most sculptured ofthe subgenus, and dae).—Proceedings ofthe Biological Society of
the deep sulcus and long sinus differentiate Washington 100:44-74.
it from its close relatives. Geographically, Penn, George H., Jr. 1952. A new crawfish of the
the position of O. (H.) hartfieldi in the Ya- Virilis Section ofthe genus Orconectes (Decap-
oda, Astacidae).—Natural History Miscellanea
zoo system is between the range of O. (H.)
109:1-7.
perfectus (Tombigbee system) and O. (H.) 1956. A new crawfish ofthe genus Procam-
.
—
hathawayi (southcentral Louisiana). barus from Arkansas (Decapoda, Astacidae).
—We
Etymology. take pleasure in naming Lloydia 19:109-119.
this crawfish in honor ofPaul D. Hartfield, Walls, Jerry G. 1972. Three new crawfishes related
to Orconectes difficilis (Faxon) (Decapoda, As-
formerly Curator of Invertebrates at the
tacidae).—Proceedings ofthe Biological Society
Mississippi Museum ofNatural Science, in ofWashington 84:449-458.
recognition ofhis vigorous efforts to collect
crawfishes from his state and thus contrib- (JFF) Department ofBiological Sciences,
ute to our knowledge. LSCB 124, University of South Alabama,
Mobile, Alabama 36688, U.S.A.; (RDS)
Acknowledgments Tulane University Museum ofNatural His-
We tory, Belle Chasse, Louisiana 70037, U.S.A.
express our thanks to the collectors
indicated in the "range" comments above