4.6 Stylocheiron maximum Hansen, 1908
S. maximum Hansen, 1908: p. 92- Hansen, 1910:
pp. 121, 122, pl. 16 fig. 6a-d- Hansen, 1912: p.
283- Zimmer, 1914: p. 438- Hansen, 1915: p. 12
- Hansen, 1916: p. 654- Tattersall, 1925: p. 11 -
Tattersall, 1926: p. 3- Tattersall, 1927: p. 27- Illig, 1930: p. 53- Ruud, 1936: p. 16 et seq., figs. 518 - Banner, 1950: pp. 39-42, pl. 4 fig. 26a-j -
Banner, 1954: p. 42 - Boden, 1954: p. 237, fig.
22a-c- Boden, 1955: p. 344- Boden et al., 1955:
pp. 391-393, fig.55- Nepgen, 1957: p. 11, pl. 12Brinton, 1962a: p. 169, figs. 81, 82 - Brinton,
1962b: p. 176- Casanova-Soulier, 1968: et seq. -
Roger, 1968: p. 38, fig. 13, tab. 1- Mauchline and
Fischer, 1969: p. 102, fig. 36- Mauchline, 197la:
p. 7, figs. 13b, 14b, 15b- Mauchline, 1971b: p. 13,
fig. 13a-f- Brinton, 1975: p. 218, figs. 116, 124d
- Antezana et al., 1976: p. 55, figs. 1-2a- Antezana and Brinton, 1981: p. 689, figs. 229-233.
Body length -
maximum length offemales: 17.8 mm
Description
Frontal plate of carapace projected on long and
pointed rostrum, extending beyond anterior
margin of eyes. Gastric region, delimited by conspicuous cervical groove, bulged and supporting
a low, short and abrupt dorsal keel. Eyes large
and transversally constricted at middle into upper and lower lobes; lower lobe varies from being
equal, narrower or broader than the other. Eyes
lacking oblong crystal cones. Basal segment of
antennular peduncle similar in males and females. 2nd segment as short and robust as 3rd in
males. Both are elongated and slender in females; 3rd is almost twice as long as 2nd. Antennular flagella of males cylindrical or somewhat
flattened, with globose basal segment bearing
severallong setae. 3rd endopodite greatly elongated, ending in a false claw formed by a fingerlike curved process on distal margin of propodus
and dactylus; this in turn projects into long
curved spine, and another 2-3 secondary spines.
Sixth abdominal segment 2.2.-2.4 times longer
than high. Terminal process of petasma somewhat longer and more robust than proxima! process. Both are sinuous. Spiniform process long
and slender. Lateral process straight and very
short.
Remarks
According to Hansen (1910), S. maximum and S.
abbreviatum form a natural group of similar
species. Brinton ( 1962b) also included S. robustum to this group, based on severa! common features. In fact, these 3 species are quite difficult to
distinguish, particularly sub-adult specimens.
The following features, suggested by Brinton
(1962a), may help in their diagnosis:
1. The upper lobe of the eyes is narrower in S.
robustum than in S. maximum, and is even
narrower in S. abbreviatum.
2. The length/height relation of the 6th abdominal segment is 2.4 in S. maximum, 1.65-2.0 in
S. abbreviatum and 1.7-1.8 inS. robustum.
3. The terminal process ends in an outward
curved process and is shorter than the proxima! process. This is not the case in S. maximum and S. abbreviatum.
4. The lateral process is very short in S. maximum.
5. The largest size and largest eyes characterize
S. maximum, while S. robustum is smaller and
stockier, and has smaller eyes.
S. maximum Hansen, 1908: p. 92- Hansen, 1910:
pp. 121, 122, pl. 16 fig. 6a-d- Hansen, 1912: p.
283- Zimmer, 1914: p. 438- Hansen, 1915: p. 12
- Hansen, 1916: p. 654- Tattersall, 1925: p. 11 -
Tattersall, 1926: p. 3- Tattersall, 1927: p. 27- Illig, 1930: p. 53- Ruud, 1936: p. 16 et seq., figs. 518 - Banner, 1950: pp. 39-42, pl. 4 fig. 26a-j -
Banner, 1954: p. 42 - Boden, 1954: p. 237, fig.
22a-c- Boden, 1955: p. 344- Boden et al., 1955:
pp. 391-393, fig.55- Nepgen, 1957: p. 11, pl. 12Brinton, 1962a: p. 169, figs. 81, 82 - Brinton,
1962b: p. 176- Casanova-Soulier, 1968: et seq. -
Roger, 1968: p. 38, fig. 13, tab. 1- Mauchline and
Fischer, 1969: p. 102, fig. 36- Mauchline, 197la:
p. 7, figs. 13b, 14b, 15b- Mauchline, 1971b: p. 13,
fig. 13a-f- Brinton, 1975: p. 218, figs. 116, 124d
- Antezana et al., 1976: p. 55, figs. 1-2a- Antezana and Brinton, 1981: p. 689, figs. 229-233.
Body length -
maximum length offemales: 17.8 mm
Description
Frontal plate of carapace projected on long and
pointed rostrum, extending beyond anterior
margin of eyes. Gastric region, delimited by conspicuous cervical groove, bulged and supporting
a low, short and abrupt dorsal keel. Eyes large
and transversally constricted at middle into upper and lower lobes; lower lobe varies from being
equal, narrower or broader than the other. Eyes
lacking oblong crystal cones. Basal segment of
antennular peduncle similar in males and females. 2nd segment as short and robust as 3rd in
males. Both are elongated and slender in females; 3rd is almost twice as long as 2nd. Antennular flagella of males cylindrical or somewhat
flattened, with globose basal segment bearing
severallong setae. 3rd endopodite greatly elongated, ending in a false claw formed by a fingerlike curved process on distal margin of propodus
and dactylus; this in turn projects into long
curved spine, and another 2-3 secondary spines.
Sixth abdominal segment 2.2.-2.4 times longer
than high. Terminal process of petasma somewhat longer and more robust than proxima! process. Both are sinuous. Spiniform process long
and slender. Lateral process straight and very
short.
Remarks
According to Hansen (1910), S. maximum and S.
abbreviatum form a natural group of similar
species. Brinton ( 1962b) also included S. robustum to this group, based on severa! common features. In fact, these 3 species are quite difficult to
distinguish, particularly sub-adult specimens.
The following features, suggested by Brinton
(1962a), may help in their diagnosis:
1. The upper lobe of the eyes is narrower in S.
robustum than in S. maximum, and is even
narrower in S. abbreviatum.
2. The length/height relation of the 6th abdominal segment is 2.4 in S. maximum, 1.65-2.0 in
S. abbreviatum and 1.7-1.8 inS. robustum.
3. The terminal process ends in an outward
curved process and is shorter than the proxima! process. This is not the case in S. maximum and S. abbreviatum.
4. The lateral process is very short in S. maximum.
5. The largest size and largest eyes characterize
S. maximum, while S. robustum is smaller and
stockier, and has smaller eyes.