Grube, 1861: 137.
Stebbing, 1906: 206.
Barnard, 1932: 114 (references).
“With the characters of the family.”
The genotype is C. pusilla Grube, 1861.
Stebbing (1906) recognised three species, C. pusilla, C. brazieri and C. hamigera. Of this last, Schellenberg (1926) remarks that it remains uncertain and that it is probably an immature male. Since then three species have been described: C. fissilingua Schellenberg, 1926; C. castellata Barnard, 1932; and C. simplicicauda Nicholls, 1938. These last three, like C. brazieri, are Southern Hemisphere species. Certain material attributed to one or other of the earlier three species has yet to be elucidated, notably Chilton's (1921) description of a specimen from Australia which he considered to be C. brazieri. It is my opinion that this last also deserves specific rank, but I have refrained from giving it a distinct specific name since I have not seen any specimens belonging to it. It is obviously close to C. magnirama which it resembles in the third uropod. Haswell states that the outer ramus of the third uropod in C. brazieri is short, but it is not of the rudimentary nature found in Chilton's specimen and in C. magnirama. As Haswell specifically states and figures, the inner ramus is not five or six times but “twice as long” as the outer.
|1 Uropod 3, rami very unequal||2|
|Uropod 3, rami subequal||3|
|2. Uropod 3, outer ramus ½ length of inner||C. brazieri Haswell, 1880|
|Uropod 3, outer ramus rudimentary, about ⅙ length inner ramus||C. magnirama n.sp.|
|3. Telson entire||4|
|Telson castellated or terminally notched||6|
|4. Maxilliped inner plate cleft; gnathopod 1, 2 or 3 strong spine-setae on end||C. simplicicauda Nicholls, 1938|
|Maxilliped inner plate entire; gnathopod 1, tuft of several setae on end||5*|
|5. Gnathopod 1, 3rd segment rather elongate||C. pusilla Grube, 1861|
|Gnathopod 1, 3rd segment not elongate||C. hamifera Kossman, 1880|
|6. Telson, lateral margins smooth, 2 notches on end||C. fissilingua Schellenberg, 1926|
|Telson, lateral and end margins castellated||7|
|7. Maxilliped base shell-like, dactylos in gnathopod 2, adult male, not more than ½ propod length||C. castellata Barnard, 1932|
|Maxilliped base a large triangular plate; gnathopod 2 dactylos. adult male, reaching back to carpus||C. subcastellata, n.sp.|
Colomastix subcastellata n.sp. (Figs. 1–31.)
Body in spirit white; eyes of a few ocelli, brownish. Sideplates small Rostrum short, acutely pointed; maxilliped base a prominent strong triangular plate behind mouthparts and extending quite deeply vertically between gnathopods. Urosome not carinate. Antennae subequal.
[Footnote] *Nicholls compares his C. simplicicauda to Southern Hemisphere species only and gives very few points which can be compared with Northern Hemisphere species. That C. pusilla and C. hamifera have an entire inner plate to the maxilliped, I accept on Schellenberg's authority. Separation of C. pusilla and C. hamifera follows Stebbing (1906), but it should be noted that the main reason for accepting the telson of C. hamifera as entire is the absence of any statement to the contrary I have not been able to see Kossman's figures.
Text-Fig. 1.—Colomastix subcastellata, n.sp. 1—Adult male. 2—Antenna 1, ♂, and rostrum. 3—Antenna 2, ♂. 4—Antenna 2. ♀. 5—Upper Lip. 6—Maxilla 1. 7—Maxilla 2. 8— Mandible. 9—Maxilliped. 10—Gnathopod 1, ♂. 11—Gnathopod 1. ♂. tip of propod. 12—Gnathopod 2, ♂. 13—Gnathopod 2, ♂, carpus and merus. 14—Pleopod. 15—Telson.
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Antennae. First: Peduncle, 1st segment width nearly ½ length, length ¾ 2nd segment; 3rd barely more than ½ length 2nd; width of 2nd ¼ length, width of 3rd nearly ⅓ length. Flagellum of 4 segments, ⅔ length 3rd peduncle segment, segments with a few long flaccid sensory and other setae inferiorly and on end. Second: Peduncle, 3rd segment ⅔ length 4th; 4th about 5/6 length 5th; width of 3rd about ½ length, of 4th less than ⅓ length, of 5th ⅙ length. Flagellum of 4 segments, about ½ length 5th peduncle segment, the 1st segment quite long and slender, a few long fine setae inferiorly and at end. Female. Peduncle, 3rd segment width ⅔ length, long and short stout spine on superodistal angle; width of 4th more than ⅓ length, 2 spines on superior margin, 2 on superodistal angle; 5th as long as 4th, slightly narrower, seta or 2 on margins and angles; flagellum as before, 4th segment rudimentary.
Mouthparts. Difficult to separate and distinguish because of their extremely small size. Mandible: Ending in 5 strong spine-teeth. Maxilla 1: Palp comparatively large, with acutely-pointed tip, a spine outside tip, inner margin notched so palp somewhat bilobed, inner margin of outer lobe has 3 or 4 fine setae, inner lobe has straight end margin with 3 or 4 spine-setae; outer plate simple with 4 or 5 end spines which give jagged appearance; short narrow inner plate has terminal seta. Maxilla 2 Partially separated lobes distally setose, inner the shorter. Maxilliped: Large subtriangular base in situ projects well below and behind rest of mouthparts; it corresponds to, but is quite different from, the shell-like (“schalenförmigen”) plate of Schellenberg's C. fissilingua, the only other species for which this has been mentioned. The structure arising medially from the plate in Fig. 20 appears to be an attachment hinge on which the maxilliped pivots Inner plates a very small tongue, split ½ their length, basos on either side of tongue produced a little to triangular tooth. Outer plate distally rounded, a small seta distally and another ⅔ along inner margin. Merus shorter than carpus, carpus about ½ as wide as long; propod a little longer than carpus, almost diamond-shaped with convex outer margin, obtusely angled inner margin has strong seta or 2 on medial angle; inner surface and margin finely combed; seta on outer distal angle, dactylos about ¾ propod length, comparatively stout and blunt although not widening appreciably towards base; inner margin finely combed.
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Gnathopods. First: Sideplate ovate, produced slightly forward; more correctly shown in Fig. 23 than in Fig. 10 which is narrower due to plate being mounted slightly obliquely on slide; much wider than deep. Basos long and slender, widening a little distally to about 1/7 length; ischium about ⅓ basos length, width about ⅓ own length; merus subequal; carpus narrower, twice merus length, greatest width about 1/10th length; propod about 4/7 carpus length, a little swollen proximally, distally narrow, truncate apex has tuft of stout spine-setae. Second: (Male). Sideplate small, ovately subrectangular. Gills as in other segments extremely small and rounded. Basos proximally constricted, widening strongly distally so distal width ⅖ length; ischium subrectangular, ⅖ basos length, width not ⅔ length; merus very small, ovate, about ½ length and width of ischium, 2 setae on free posterior margin. Carpus larger, subtriangular, ¾ ischium length but extremely wide since it is posteriorly produced in rounded lobe between merus and propod, about 5 pairs of spine-setae posteriorly and continuous with them on the free posterodistal margin of lobe a row of 6 or more. These spines are peculiarly widened basally (cf Fig. 18). Propod greatly expanded, greatest width ½ length, basos only about ⅖ propod length, elongate-ovate, anterior margin
Text-Fig. 2.—Colomastix subeastellata. n. sp. 16—Gnathopod 2, immature ♂. 17—Gnathopod 2 immature ♂, propod tooth. 18—Gnathopod 2, spine-seta from carpus lobe. 19—Maxilliped, dorsal view. 20—Maxilliped, lateral view. 21—Gnathopod 2. ♀. 22—Peraeopod 1, ♀. 23— Gnathopod 1. ♀. sideplate. 25–29—Sideplates of peraepods, 1–5. 29–31—Uropods 1–3, ♂. Colomastix magnuma, n. sp. 32—Maxilliped. dorsal view. 33—Maxilliped, lateral view.
convex; posterior also convex but produced in blunt tooth with 2 or 3 setae immediately inside dactylos, a strong narrow tooth at ¾, margin between these teeth excavate; a further similar tooth with ring of setae near base arising proximally on posterior surface from distinct ridge, tooth about ¼ along margin; row of 14 or so setae along posterior surface a little anterior to ridge from tooth to below dactylos insertion; a similar row along anterior surface and slightly in from margin. Although otherwise illustrated to emphasise teeth, the dactylos actually passes between the distal teeth on the one side and the proximal tooth and ridge on the other. Dactylos slender but strong, curved and as long as propod, inner margin slightly swollen proximally opposite excavation between distal teeth. (Female). Basos width ⅓ length; ischium about ⅓ basos, width ⅔ length. Merus as long and as wide, subrectangular, a few bristles ½ along posterior margin, 2 setae at ¾ (which represents posterodistal angle); carpus large, subtriangular, distal width ⅔ length, length ¾ basos; anterior margin fairly straight, posterior a little convex, about 5 sets of single or paired setae on margin, strong row on distal angle which extends somewhat posteriorly to propod base; propod ovately triangular, as long as basos, proximally ½ carpus width but posterior margin strongly convex so medially as wide as carpus, then more or less straight and narrowing to quite sharp angle with slightly convex anterior margin; 2 setae about ⅓ along anterior margin, a number of long setae right along posterior margin (14 or so) to dactylos which is a short slender finger, less than ½ propod length and arising noticeably below end of propod, 2 or 3 long setae outside dactylos on distal angle; posterior surfaces of propod and carpus finely bristled.
Peraeopods. Except that 3rd to 5th are reversed, as is normal in Gammaridea, and except for slight proportional differences, the peraeopods are sufficiently alike for one description to serve for all. The sideplates differ slightly as illustrated. First: Basos widest distally, width about ⅓ length. Ischium subrectangular, width about ⅔ length, length ⅓ basos. Merus width ½ length, length ½ basos, anterior margin straight, posterior expanded and somewhat convex distally, produced a little down carpus in acute angle with 1 or 2 small setae; carpus slightly shorter, small seta or 2 anterodistally, 2 on anterior margin; propod narrower, linear, about ¾ basos length, 2 or 3 minute spines on anterior margin. Curved dactylos about ½ propod length.
Epimeral Plates. Ovately subrectangular.
Pleopods. Rami as long as peduncle, of 4 and 5 segments, inner ramus slightly the shorter, 2 coupling spines on peduncle.
Uropods. All reaching approximately same distance; rami lanceolate, both margins finely pectinate, the outer ramus slightly the shorter (from almost equal with inner in 1st to about ¾ its length in 3rd); peduncle as long as rami in 1st and 2nd, about ⅔ their length in 3rd; inner distal angle produced a little in 1st and 2nd; inner margin a little pectinate distally in 3rd, distal ½ pectinate in 2nd, entirely pectinate in 1st. Telson: Length twice width, distally narrowing, 2 narrow fissures in end margin, about 5 indentations or castellations along each lateral margin.
Types. Male, length 3 ½ mm., slides P.68; female, length 2 ½ mm., slides P.69, Paratypes: Male, P.73; females, P.69. P.70, P.74.
Localities. Portobello Marine Biological Station, Otago Harbour, surface, taken at jetty with light, E. J. Batham, 1/9/53 (1 male, 2 females, slides P.68–70;
one of females with 8 ova); P.M.B.S., off Pyura pachydermatina stalk covered with the polyzoan Elzerina blainvilli (Lamaroux), 20/5/52, coll. D. E. Hurley, (1 male, 1 female, slides P.73, 74).
Remarks. The telson resembles that of C. castellata, from whence the specific name subcastellata, but the male gnathopod is quite different from that of any previously recorded species, granting always that the other gnathopods described were from mature specimens. The extremely long dactylos and the three-toothed propod are characteristic. The maxilliped base is also distinctive. In the absence of any indication to the contrary, it would seem that all other recorded species have the shell-type base as described by Schellenberg. If this is so, this distinction may some to be considered to be of generic rank, but I do not consider it such on present material.
I find it extremely difficult with limited material to mount gnathopods and peraeopods of this genus so that the sideplates lie flat. For this reason only, I do not like to place too much stress on the distinctively shaped sideplate figured by Barnard (1932) for gnathopod 1 of C. fissilingua. It could just possibly be due to oblique mounting.
A further specimen not mentioned above is apparently a juvenile male of C. subcastellata. The only difference I can find is in the second gnathopod which I have illustrated (Figs. 16, 17). Essentially, it resembles the adult male described already but the dactylos reaches only as far as the proximal tooth which, like the distal teeth, is not strongly developed. Nevertheless the specimen is quite large, 3 ½ mm. (Slide P.72, coll. P.M.B.S. off Pyura pachydermatina stalk, D. E. H., 24/5/52).
I have also figured, in broad outline, the maxilliped of this specimen (Fig. 19) since it has the large triangular plate and illustrates particularly well in dorsal view the great development of the base. It may be compared with that of the following species shown in Fig. 32 From this aspect, one has the impression of the maxilliped proper fitting into the plate as if into a sheath or socket.
Colomastix magnirama n.sp. (Figs. 32–49.)
(non) C. brazieri Haswell. Chilton, 1912: 485.
Chilton, 1921: 64.
Body somewhat plump and cylindrical; more solid than previous species. Maxilliped base not prominent in situ. Third uropods greatly enlarged so that 1st and 2nd, which extend as far as the telson, reach only to the end of the peduncle if the 3rd. Like C. subcastellata otherwise except for following details.
Antennae. First: Peduncle stout; 1st segment width about ¾ length, a small stout spine on each side of the slightly produced inferodistal angle; 2nd about ¾ length 1st, width ⅔ length, short spine on inferodistal angle; 3rd slightly shorter, width about ⅗ length, distal angles produced a little around base of very small flagellum which is about ½ length of 3rd segment. This flagellum is of 2 or possibly 3 distinct segments, the last rudimentary, but has 2 or 3 long terminal setae, 1 or 2 setae superiorly, and about 5 or 6 long flaccid sensory setae interiorly. These last are each on a distinctive raised base almost as large as the 2nd segment suggesting a coalescence of several segments, although the female specimens indicate that the first 3 or 4 are perhaps more correctly shown as a transverse row across the segment than as a consecutive marginal row. Chilton (1921: 62) also notes this in relation to the second antennae of the specimen he describes from
Text-Fig. 3.—Colomastix magnirama, n.sp. 34—Antenna 1, ♂. 35—Antenna 2, ♂. 36—Mandible. 37—Gnathopod 2, ♂. 38—Gnathopod 2, ♀. 39—Peraeopod 1, ♂. 40—Peraeopod 1, ♂, posterior margins of propod and dactylos. 41—Peraeopod 3, ♂. 42—Peraeopod 3, ♂, posterior margins of carpus and propod showing spines and carpus tooth. 43—Urosome. 44—Uropod 1, ♂. 45—Uropod 1, ♀. 46—Uropod 2, ♂. 47—Uropod 2, ♀. 48—Uropod 3, ♂. 49—Telson.
Australia as C. brazieri. Second: Peduncle, 3rd segment almost as wide as long, a small stout spine on superodistal angle; 4th barely longer, width nearly ½ length, small stout spine at ½ and 2 at end of superior margin; 5th about ¾ length 4th, width ½ length; flagellum of 4 segments, about ⅔ length 5th peduncle segment, long setae on segment angles, 1st flagellar segment longer than rest combined.
Mouthparts. Mandibles: Four strong spines on end, blunt molar process on inner margin. Maxilliped: Dactylos perhaps shorter than in C. subcastellata; inner plate appears only slightly left at tip. The only other difference noted is the shell-shaped basal plate. This appears to be a buffer socket in which the base of the maxilliped proper sits; whereas the large basal plate in C. subcastellata looks more like a counterweight to the rest of the maxilliped, the whole pivoting on a central hinge.
Gnathopods. Second (Male): Sideplate ovate. Basos margins straight, posteriorly widening distally so distal width ½ length and twice proximal width. Ischium width ¾ length, length nearly ½ basos. Merus small, somewhat spoon-shaped; width about ½ length, length ½ basos, 3 spine-setae near posterodistal angle. Carpus subtriangular, as long as ischium but produced posteriorly in rounded lobe between merus and propod so length about ⅔ width; as wide as propod. Propod elongate-ovate, nearly ½ as long again as basos, width ½ length, anterior margin slightly convex, posterior more strongly so; about 4 sets of 1 or 2 setae on anterior surface and angle; about 4 times as many along posterior surface near margin; a small depression, almost a pocket, on posterior margin about ⅔ for tip of strong curved dactylos which is about ½ propod length. Female: Basos width ¼ length, narrowing a little proximally, ischium ⅓ basos length, width ⅓ length. Merus ⅖ basos length, like male with 2 spine-setae posteriorly. Carpus subtriangular, ⅔ basos length, widening distally to ½ length; 4 pairs of spine-setae on posterior margin, about 5 spine-setae on free distal margin. Propod ovate-triangular, as long as carpus, widest about ⅓ where width nearly ½ length; 2 spine-setae ⅓ along slightly convex anterior margin; convex posterior margin has 3 rows of 3 to 5 spine-setae at regular intervals. Dactylos comparatively slender, not ½ propod length, arising a little below tip which has 3 long spine-setae.
Peraeopods. First & Second: Similar. Basos widening a little distally, distal width ⅓ length. Ischium width ¾ length, length ⅓ basos. Merus length ½ basos, width ⅔ length, anterior margin a little constricted proximally, slightly convex. Carpus slightly shorter than merus, about ¾ merus width. Propod a little swollen proximally, narrowing to dactylos. Length ⅔ basos, width about ⅓ length; posterior margin has 3 or 4 small distinct spine-teeth, margin minutely and not very distinctly pectinate. Stout dactylos not ½ propod length, minutely pectinate as far as small but distinct spine-tooth halfway along. Third: Sideplate ovate-elongate, about 3 times as wide as deep. Basos a little constricted proximally, with double anterior margin; width barely ½ length. Ischium ⅓ basos length, not quite as wide as long. Merus ⅗ basos length, posterior margin straight, anterior slightly convex and widening distally so distal width about ⅔ length; produced anterodistally a little along carpus. Carpus ⅔ merus length, distally as wide as long, anterior margin slightly convex and distally widening; posterodistal angle produced in pronounced sharp tooth; small spine-tooth ½ along posterior margin which, like distal tooth, is minutely pectinate. Propod arising from anterior ½ of
carpus distal margin, slightly swollen medially, width ⅓ length, length ¾ basos; 2 or 3 small sharp spine-teeth on minutely pectinate posterior margin; dactylos as before. Fourth & Fifth: Sideplates not so wide, otherwise similar.
Uropods. First: Outer ramus barely ⅖ length inner, about ⅗ peduncle length; outer bluntly spatulate with finely pectinate margins; inner lanceolate with narrow spine-like tip, although ramus somewhat distorted in my specimen. Outer ramus in female about ¾ length of inner, the outer slightly shorter and inner slightly longer than peduncle. Second: Rami lanceolate, as long as peduncle, inner slightly the longer in male, outer not nearly so subequal with inner in female; margins finely pectinate, tips acute. Third: Outer ramus a minute spine, at most ½ length small peduncle; inner ramus a great lanceolate-crescentic blade with pectinate margins, nearly 4 times peduncle length and approximately 7 or 8 times that of outer ramus. Telson: Entire, tapering to rounded tip with only two faint indentations either side of tip, made more noticeable by thread-like marks coming away from them than by their own distinctness.
Types. Male, length 2 ½ mm., Slides P.71; female, length 3 mm., Slides P.75. Paratype: Female, Slide P.76.
Localities. Off Elzerina-encrrusted Pyura pachydermatina stalk, P.M.B.S., 24/5/52, coll. D.E.H.
Remarks. The differences in the male and female 1st uropods may be due to an aberrantly short outer ramus in the male specimen, but are probably valid sexual differences.
This species may be distinguished from any of the previous validly identified species by the remarkable third uropods. This condition, however, also applies in a specimen partially figured and described from Australia as C. brazieri by Chilton (1921). Haswell's original description and figures (1880) cannot by any stretch of the imagination be made to fit C. magnirama or the specimen described by Chilton, at least in regard to the third uropods. On the basis of the specimens I have seen I cannot accept Chilton's suggestion that “probably as the animal develops the inner ramus becomes longer in proportion” as a reasonable explanation of the differences in third uropods.
It is clear then, that Chilton's C. brazieri from Port Chalmers, New Zealand, and his C. brazieri from Australia cannot be accepted as belonging to Haswell's C. brazieri which needs further description. The Port Chalmers specimen belongs to C. magnirama, showing, amongst other characteristics, the carpus tooth in peraeopods 3–5. The Australian specimen is, at first glance, also C. magnirama, but closer examination of his figures suggests that it is yet another species. The antennae are much more spinous, the male second gnathopod appears to be quite different; the third uropod outer ramus is not so markedly rudimentary, and, in my opinion most important of all, there is no carpus tooth in peraeopods 3–5. This last is an important characteristic of C. magnirama.