Type locality. An ephemeral pond on the south side of
EI Refugio bridge, 70km E Torreon, Coahuila, Mexico.
Diagnosis. Male. Peduncle of distal outgrowth of long
type, without pulvinus, and no protuberances on any
side; spur subacuminate; lateral lamella with acute
angle between distal part of thumb and spur; inner
lamella medioventrally produced forming a cavity; distal part of thumb inerm, dorsally curved along its extension, apex subacuminate; finger bigeniculate, two teeth
on inner dorsal side of proximal part; proximal one a
small hump-like tooth, distal one an oblique spiniform
tooth, anterodorsally directed; apex of finger lamellar,
with a subterminal ventral lobe; frontal appendage simple, short, bilobed at tip; genitalia without linguiform
outgrowths; cercopods setose along inner and lateral
borders; anus terminal.
Female. Ovaries uniramous extending from genital
segment 1 to abdominal segment 6; brood pouch ends
at segment 6; cysts sphaerical, ornamented by wide
ribs forming polygonal areas.
Differential diagnosis. In antennal morphology, S. guzmani n. sp. appears to be the simplest species of the
whole torvicornis group. S. guzmani presents no structures, nor protuberances on any region of the peduncle
(Fig. 5 A-C). Thus, it is easy to differentiate from the
other American species of the torvicornis subgroup, S.
mattoxi n. sp., because the latter has a series of conical protuberances on the median side of the distal part
of the peduncle, including a spiniform structure at the
base of the hand, and by the crenate dorsal margin
of the distal part of the thumb (Fig. 6 C). Moreover,
the finger of S. mattoxi is broader at the first geniculation, and the apex, after a ventral lobe, is longer and
acuminate. Comparing S. guzmani with members of
the mackini subgroup, the new species can be distinguished by the characters mentioned above, and by its
hump-like proximal tooth.
In all samples, S. guzmani was collected together
with S. (gr. torvicornis) mackini. The problem of distinguishing the corresponding females, was solved by
observing that S. mackini female has, like the other
members of the mackini subgroup, biramous ovaries,
while S. guzmani female has uniramous ovaries.
Distribution. Streptocephalus guzmani is endemic to
the Region Lagunera, southern Coahuila, Mexico, and
is known only from two localities. One, the type locality, is situated on the south margin of the ancient Laguna
de Mayran, RIo Nazas basin. The second one is on the
25
e~st margin of the ancient Laguna de Viesca of the Rio
Aguanaval basin.
Etymology. The species is named in honor of Eduardo
Guzman-Lozano, researcher at the Instituto de Investigaciones Cientificas del Estado de Coahuila, Unidad
Laguna, who was co-collector with the first author, of
many phyllopod samples.
Streptocephalus mattoxi n. sp.
(Fig. 6 A-E)
Streptocephalus sp. C. Maeda-MartInez et al.
(1995; this volume).
Type material. Holotype d' 15.0 mm, allotype Q 15.5
mm, USNM 259676, 259677. Paratypes 30 d' 14.4
(12.1-l6.3)mm,11 QQ 12.4 (11.1-15.7)mm, USNM
259678-9, DB 863, UG 235, collected 29 September
1988 by Denton Belk in the type locality; Additional
specimens 17 d'd' 12.3 (10.5-13.4)mm, DB 862, collected 29 September 1988 by D. Belk in playa 12.2 km
south of Sarita on east side of US 77, Kenedy County,
Texas, USA.
Type locality. Playa 12.4 km south of Sarita on east
side of US 77, Kenedy County, Texas, USA.
Diagnosis. Male. Peduncle of distal outgrowth of long
type, without pulvinus, but with series of about 14 conical protuberances on inner side of distal part; inner dorsal side of base of hand with spiniform structure, anteriorly directed; spur triangle-shaped, apex with digitiform prolongation; lateral lamella with acute angle
between distal part of thumb and spur; inner lamella
medioventrally produced, forming a cavity; distal part
ofthumb geniculate, forming an elbow on ventral side,
dorsal margin slightly crenate, apex acuminate; finger
bigeniculate, two teeth on inner dorsal side of proximal part, proximal one a small acute tooth, distal one
an oblique digitiform tooth, anterodorsally directed.
First geniculation of finger with a broad dorsallamella which is narrow at second geniculation; apex of
finger acuminate, with sub-apical, slightly bifid ventrallobe; frontal appendage simple, short, and bilobed
at tip; genitalia without linguiform outgrowths; cercopods setose along inner and lateral borders; anus
terminal.
Female. Ovaries uniramous extending from genital
segment 1 to abdominal segments 3-5; brood pouch
ending on segments 3-4; sphaerical cysts, ornamented
EI Refugio bridge, 70km E Torreon, Coahuila, Mexico.
Diagnosis. Male. Peduncle of distal outgrowth of long
type, without pulvinus, and no protuberances on any
side; spur subacuminate; lateral lamella with acute
angle between distal part of thumb and spur; inner
lamella medioventrally produced forming a cavity; distal part of thumb inerm, dorsally curved along its extension, apex subacuminate; finger bigeniculate, two teeth
on inner dorsal side of proximal part; proximal one a
small hump-like tooth, distal one an oblique spiniform
tooth, anterodorsally directed; apex of finger lamellar,
with a subterminal ventral lobe; frontal appendage simple, short, bilobed at tip; genitalia without linguiform
outgrowths; cercopods setose along inner and lateral
borders; anus terminal.
Female. Ovaries uniramous extending from genital
segment 1 to abdominal segment 6; brood pouch ends
at segment 6; cysts sphaerical, ornamented by wide
ribs forming polygonal areas.
Differential diagnosis. In antennal morphology, S. guzmani n. sp. appears to be the simplest species of the
whole torvicornis group. S. guzmani presents no structures, nor protuberances on any region of the peduncle
(Fig. 5 A-C). Thus, it is easy to differentiate from the
other American species of the torvicornis subgroup, S.
mattoxi n. sp., because the latter has a series of conical protuberances on the median side of the distal part
of the peduncle, including a spiniform structure at the
base of the hand, and by the crenate dorsal margin
of the distal part of the thumb (Fig. 6 C). Moreover,
the finger of S. mattoxi is broader at the first geniculation, and the apex, after a ventral lobe, is longer and
acuminate. Comparing S. guzmani with members of
the mackini subgroup, the new species can be distinguished by the characters mentioned above, and by its
hump-like proximal tooth.
In all samples, S. guzmani was collected together
with S. (gr. torvicornis) mackini. The problem of distinguishing the corresponding females, was solved by
observing that S. mackini female has, like the other
members of the mackini subgroup, biramous ovaries,
while S. guzmani female has uniramous ovaries.
Distribution. Streptocephalus guzmani is endemic to
the Region Lagunera, southern Coahuila, Mexico, and
is known only from two localities. One, the type locality, is situated on the south margin of the ancient Laguna
de Mayran, RIo Nazas basin. The second one is on the
25
e~st margin of the ancient Laguna de Viesca of the Rio
Aguanaval basin.
Etymology. The species is named in honor of Eduardo
Guzman-Lozano, researcher at the Instituto de Investigaciones Cientificas del Estado de Coahuila, Unidad
Laguna, who was co-collector with the first author, of
many phyllopod samples.
Streptocephalus mattoxi n. sp.
(Fig. 6 A-E)
Streptocephalus sp. C. Maeda-MartInez et al.
(1995; this volume).
Type material. Holotype d' 15.0 mm, allotype Q 15.5
mm, USNM 259676, 259677. Paratypes 30 d' 14.4
(12.1-l6.3)mm,11 QQ 12.4 (11.1-15.7)mm, USNM
259678-9, DB 863, UG 235, collected 29 September
1988 by Denton Belk in the type locality; Additional
specimens 17 d'd' 12.3 (10.5-13.4)mm, DB 862, collected 29 September 1988 by D. Belk in playa 12.2 km
south of Sarita on east side of US 77, Kenedy County,
Texas, USA.
Type locality. Playa 12.4 km south of Sarita on east
side of US 77, Kenedy County, Texas, USA.
Diagnosis. Male. Peduncle of distal outgrowth of long
type, without pulvinus, but with series of about 14 conical protuberances on inner side of distal part; inner dorsal side of base of hand with spiniform structure, anteriorly directed; spur triangle-shaped, apex with digitiform prolongation; lateral lamella with acute angle
between distal part of thumb and spur; inner lamella
medioventrally produced, forming a cavity; distal part
ofthumb geniculate, forming an elbow on ventral side,
dorsal margin slightly crenate, apex acuminate; finger
bigeniculate, two teeth on inner dorsal side of proximal part, proximal one a small acute tooth, distal one
an oblique digitiform tooth, anterodorsally directed.
First geniculation of finger with a broad dorsallamella which is narrow at second geniculation; apex of
finger acuminate, with sub-apical, slightly bifid ventrallobe; frontal appendage simple, short, and bilobed
at tip; genitalia without linguiform outgrowths; cercopods setose along inner and lateral borders; anus
terminal.
Female. Ovaries uniramous extending from genital
segment 1 to abdominal segments 3-5; brood pouch
ending on segments 3-4; sphaerical cysts, ornamented