Catapagurus franklinae, Mclaughlin, Patsy A., 2004

Mclaughlin, Patsy A., 2004, A reappraisal of the hermit crab genera Catapagurus A. Milne­ Edwards and Hemipagurus Smith (Crustacea: Decapoda: Anomura: Paguridae), with the description of a new species, Zootaxa 433, pp. 1-16 : 3-10

Catapagurus franklinae n. sp. ( Figs. 1 , 2 )

Material examined. Queensland, Australia. Holotype: male 3.0 mm, off Tully, Queensland, R/V Franklin stn 1–3, 18°07.9’S, 147°35.7’E, 956–969 m, 6 May 1986 (QM W26577). Paratypes: 1 female 3.5mm, ovig. female 2.2 mm, off Innisfail, Queensland, R/ V Franklin stn 45–3, 17°33.1’S, 146°55.9’E, 908–926 m, 16 May 1986 (QM W16593); 2 males 1.5, 2.1 mm, 1 ovig. female 2.4 mm, off Innisfail, R/V Franklin stn 43–2, 17°34.6’S, 146°53.2’E, 485–500 m, 15 May 1986 (QM W16594); 1 male 2.3 mm, off Tully, Queensland, R/V Franklin stn 44–3, 17°36.9’S, 146°57.4’E, 672–744 m, 15 May 1986 (QM W16611); 1 male 1.8 mm, 1 ovig. female 2.3 mm, off Tully, R/V Franklin stn 48–2, 17°50.7’S, 147°18.2’E, 703 m, 17 May 1986 (QM W16592); 1 male 1.8 mm, off Tully, R/V Franklin stn 49–3, 17°51.1’S, 147°09.9’E, 904–925 m, 17 May 1986 (QM W16597); 1 ovig. female 2.3 mm, off Tully, R/V Franklin stn 47–3, 17°51.5’S, 147°07.8’E, 505– 503 m, 16 May 1986 (QM W16607); 1 male 1.5 mm, off Tully, R/V Franklin stn 46–3, 17°55.4’S, 147°01.0’E, 295–309 m, 16 May 1986 (QM W16609); 1 female 2.8 mm, 1 ovig. female 3.3 mm, off Tully, R/V Franklin stn 50–3, 18°01.7’S, 147°20.5’E, 918– 891 m, 17 May 1986 (QM W16606); 1 male 3.1 mm, 1 female 3.2 mm, 1 ovig. female 3.2 mm, off Tully, R/V Franklin stn 1–3, 18°07.9’S, 147°35.7’E, 956–969 m, 6 May 1986 (QM W16610); MUSORSTOM 5, New Caledonia, 1 male 2.1 mm, stn 341, 19°45.9’S, 158°43.4’E, 620–630 m, 16 Oct 1986 (MNHN­Pg 6403); 2 males 2.4, 2.7 mm, 1 female 2.2 mm, 1 ovig. female 2.3 mm, stn 275, 24°46.6’S, 159°40.3’E, 285 m, 9 Oct 1986 (MNHN­Pg 6402); MUSORSTOM 6, New Caledonia, 1 ovig. female 3.0 mm, stn 438, 20°23.0’S, 166°20.1’E, 780 m, 18 Nov 1989 (MNHN­Pg 6404); VOLSMAR New Caledonia, 1 male 2.2 mm, 1 ovig. female 3.1 mm, stn DW 7, 22°26.0’S, 171°44.1’E, 400 m, 1 Jun 1989 ( USNM 1008753); GEMINI, New Caledonia, 1 ovig. female 2.0 mm, stn DW 51, 20°58.5’S, 170°03.4’E, 450 m, 4 Jul 1989 (MNHN­Pg 6405); SMIB 5, New Caledonia. 2 males 1.8, 1.9 mm, 1 ovig. female 2.0 mm, stn DW 87, 22°18.7’S, 168°41.3’E, 370 m, 11 Sep 1989 (MNHN­Pg 6401); Western Tasman Sea, 1 male 2.5 mm, R/V Franklin stn FRO589–36, 26°41.45’S, 159°26.70’E, 292 m, 8 May 1989 (AM P39446).

Description. Shield ( Fig. 1 A, B) slightly to distinctly broader than long; anterior margin between rostral lobe and lateral projections concave; anterolateral margins sloping; posterior margin truncate and frequently with median indentation; dorsal surface with few scattered, fine setae; carapace lateral lobes narrow, weakly to moderately well calcified. Rostral lobe broadly and roundly triangular, usually produced to approximate level of prominent lateral projections. Lateral projections broadly and roundly triangular, each usually with terminal, submarginal or marginal spinule. Posterior carapace 0.3–0.8 length of shield; posterolateral plates narrow to moderately wide anteriorly, drawn out into relatively thin bands reaching to posterior margins, posterior median plate short. Third maxillipeds each with crista dentata consisting of 7–10 small teeth; accessory tooth prominent.

Ocular peduncles short, corneal diameter 0.5–0.8 peduncular length. Ocular acicles narrowly triangular, slender, reaching from approximately midlength of peduncle to slightly beyond bases of corneas, terminating acutely; very widely separated.

Antennular peduncles overreaching distal margins of corneas by 0.2–0.8 length of penultimate segments. Ultimate segment with 2 to several long, fine setae at dorsodistal margin and several short setae on dorsal surface. Penultimate segment with few scattered, short or very short setae. Basal segment with very prominently produced, subacute ventrodistal margin.

Antennal peduncles overreaching distal margins of corneas by 0.2–0.9 length of ultimate segments. Fifth and fourth segments with few, scattered short setae. Third segment with few setae on unarmed ventrodistal angle. Second segment with produced dorsolateral distal angle reaching to or beyond base of fourth peduncular segment, terminating in small spine or spinule, occasionally with tiny spinule on lateral margin distally; dorsomesial distal angle with prominent spine. First segment occasionally with small spine at dorsolateral distal angle, usually with 1 small spine at ventrodistal angle. Antennal acicles varying in length from reaching slightly beyond bases of fifth peduncular segments and not overreaching distal margins of corneas to overreaching corneal margins by 0.5 acicular length; with small terminal spinule. Antennal flagella quite long, but not overreaching outstretched, very elongate ambulatory legs; each article usually with 2 minute setae.

Right cheliped ( Fig. 2 A) long, moderately slender. Dactyl 0.5–0.9 length of palm; weakly convex dorsal surface smooth or minutely granular on mesial half and with few sparse tufts of setae; dorsomesial margin faintly delimited and armed with row of tiny spinules in small specimens, becoming rounded and minutely granular with increased animal size; cutting edge with row of very small, individual or partially to completely fused calcareous teeth, 1 larger tooth at midlength and second larger tooth proximally; slightly overlapped by fixed finger. Palm 0.8 to approximately equaling length of carpus; dorsomesial margin not delimited, rounded surface with irregular rows of minute spinules or tiny tubercles, dorsolateral margin with row of very small spinules or tubercles, extending onto distal half of fixed finger in small specimens but becoming indistinct with increasing animal size, all surfaces minutely granular; fixed finger with sparse tufts of setae, cutting edge with row of small calcareous teeth, 1 somewhat larger tooth at midlength and large tooth at proximal margin. Carpus equal to or slightly longer than merus; dorsomesial margin with irregular row of very small or small spines and sparse tufts of setae, dorsodistal margin often minutely spinulose, dorsal surface with few scattered setae and covering of tiny spinules or tubercles extending onto lateral face, dorsolateral margin not distinctly delimited; lateral, mesial and ventral surfaces all with covering of tiny or minute spinules, tubercles or granules. Merus subtriangular; dorsodistal margin with or without tiny spine and few fine setae, dorsal surface with few short, transverse ridges, each with few moderately short setae or bristles, few setae posteriorly; mesial and lateral faces granular or weakly tuberculate; ventrolateral and ventromesial margins each with irregular row of very small spines, largest distally, ventral surface spinulose or tuberculate. Ischium unarmed.

Left cheliped ( Fig. 2 B–D) slender, slightly shorter to slightly longer than right; dactyl and fixed finger curved ventrally, particularly in males. Dactyl 0.3–0.6 longer than palm; dorsomesial margin with row of minute tubercles, not usually extending to distal half, convex dorsal surface minutely granular at least proximally and with scattered, moderately long setae; cutting edge with row of tiny corneous teeth. Palm 0.3–0.5 length of carpus; dorsomesial and dorsolateral margins only faintly delimited, surfaces with few scattered setae and all minutely granular, granules most prominent dorsally; fixed finger also with granular surfaces, few scattered long setae, particularly ventrally; cutting edge with few, tiny calcareous teeth, interspersed with minute corneous teeth. Carpus as long or slightly longer than merus; dorsomesial and dorsolateral margins each with somewhat irregular row of small spines or spinules and sparse setae, dorsal surface with scattered tiny spinules; mesial, lateral and ventral surfaces with coverings of tiny tubercles or granules. Merus with or without very small to tiny spine at dorsodistal margin, dorsal surface with few protuberant, short, transverse ridges and sparse setae or bristles in distal 0.5; lateral, mesial and ventral surfaces all with coverings of tiny tubercles and spinules, ventromesial and ventrolateral distal angles each with very small spinule. Ischium unarmed.

Second and third pereopods ( Fig. 2 E–G) very elongate, considerably overreaching chelipeds. Dactyls not blade­shaped; in dorsal view, straight; in lateral view, curved ventrally in distal half; second pereopods shorter than third, but both 0.2–0.6 longer than propodi, dorsal margins each with row of moderate to long setae, longer and more bristle­like distally, occasionally microscopically serrate posteriorly; mesial faces each with row of minute, almost translucent corneous spinules near or adjacent to ventral margin, often barely discernable; lateral faces and ventral margins unarmed. Propodi approximately twice length of carpi; surfaces all minutely spinulose or granular and with few setae dorsally. Carpi 0.5–0.7 length of meri; dorsal surfaces each with irregular row of very small to small spines, strongest distally; lateral, mesial and ventral surfaces granular. Meri each with 2–4 subdistal, low protuberances or occasionally small spines in small specimens and sparse setae or bristles on minutely or weakly granular dorsal surfaces; mesial faces with few scattered setae; lateral and ventral surfaces minutely tuberculate or spinulose. Ischia unarmed. Sternite of third pereopods with narrowly subrectangular anterior lobe. Fourth pereopods weakly subchelate, with moderately well developed preungual process usually not extending beyond tip of claw. Fifth pereopods chelate.

Males with moderate to long right sexual tube usually not curved dorsally over abdomen or not reaching abdominal midline ( Fig. 1 A) in large specimens, but longer and dorsally curved over abdomen in some small specimens. Males with 3 unpaired left pleopods; females with 4.

Telson ( Fig. 1 C, D) with lateral indentations suggesting separation of anterior and posterior portions; roundly triangular posterior lobes separated by moderately deep V or Ushaped median cleft, each terminating in small spine; oblique or straight inner margins with 1–3 tiny spinules or small spines, rarely just 1 or 2 tiny bristles, lateral margins often chitinous.

Egg size. Of the 29 specimens of C. franklinae n. sp., examined, 12 were ovigerous females, varying in shield length from 2.0 mm to 3.3 mm. Although egg­bearing females were collected in May, July, October, and November, none of the eggs appeared close to hatching (eyed). Eggs in early stages of development measured 0.6–0.8 mm in diameter, with approximately 20– 40 eggs being carried on each of pleopods 2 to 4. However, because the eggs could be easily detached, there was no accurate means for determining fecundity.

Sexual dimorphism. There appears to be a tendency in males for the dactyl and fixed finger of the left cheliped to develop a much more pronounced ventral curvature ( Fig. 2 C, D)

Variation. Asakura (2001) specified four measurements as differentiating characters between Catapagurus and Hemipagurus , i.e., ratio of the posterior carapace length to shield length, ratio of width to length of the sternite of the second pereopods, abdominal length and abdominal breath. At least in C. franklinae n. sp., it has been found that the length of the posterior carapace in relation to the length of the shield decreases with increased animal size. No criteria for measuring the length and width of the sternite of the second pereopods were given by Asakura, and this sternite, while it was illustrated ( Asakura 2001, figs. 5D, 7C) for two species, it was not described for any. The sternite of the second pereopods in C. franklinae is almost completely divided into two asymmetrical halves, with a deep v­shaped groove anteriorly, making length measurements unreliable. Neither were criteria given for measuring the length of the membranous abdomen nor its diameter. Given the abdominal tendency for curvature, no comparative measurements could be made on specimens of C. franklinae . However, abdominal length very well may be correlated to habitat (cf. McLaughlin 2003b); and abdominal breadth or diameter is under hydrostatic control (cf. Chapple 1973a, b), thus of questionable taxonomic significance.

Morphological variations in specimens of C. franklinae n. sp., such as those seen in the lengths of the shield and posterior carapace, antennular and antennal peduncular lengths, corneal dilation, ratios of segmental lengths, armature of chelipeds, ambulatory legs, and telson all have been incorporated into the species’ description, and clearly are substantive. Although the data are too limited for statistical correlation, three variables appear directly related to, or influenced by, growth and/or size, and all three have had major influences on current taxonomic evaluations. The first is the armature of the meri of the second and third pereopods. While most specimens of C. franklinae were found to exhibit only low protuberances subdistally on the dorsal surfaces, in one of the smallest males (1.5 mm) and one of the smallest ovigerous females (2.0 mm), one tiny distal and one or two small subdistal spines are present on the dorsal surface of each of the second and third meri ( Fig. 2 G). The representation of these spines in larger specimens by only protuberances is in keeping with the tendency, in this species, for reduction in spine prominence with increase in animal size.

The second variable was found in sexual tube length. Large males (e.g. 3.0, 3.2 mm) had relatively short sexual tubes ( Fig. 1 A), smaller specimens (e.g. 1.5–2.2 mm) frequently had appreciably longer sexual tubes that usually extended entirely over the abdomen. As pointed out by Lemaitre & McLaughlin (2003), our knowledge of development in sexual tubes is very limited; however, it might be speculated that sexual tube length is greatest with the onset of sexual maturity, and does not increase proportionally with increased animal size. If this should prove to be the case, the differences seen between the small specimens of species assigned by Asakura (2001) to Hemipagurus and the larger specimens of species assigned to Catapagurus could be accounted for simply as growth related phenomena.

The third variable was found in the shape and armature of the telson. As may be seen in the telson of the largest male paratype ( Fig. 1 C), the posterior lobes are separated by a narrow V­shaped cleft; the oblique terminal margins are armed with small spines and the terminal spines are calcareous. In contrast, in the smallest male ( Fig. 1 D), the posterior lobes are separated by a broad U­shaped cleft; the straight terminal margins are unarmed, and the terminal spines are chitinous. In the specimens available, there appeared to be a tendency for reduction in the breadth of the median cleft with increased animal size. Although often considered a diagnostic specific character, it must be pointed out that at least in Catapagurus , substantial intraspecific variations in telson shape and armature can be anticipated.

Coloration. Unknown.

Habitat. One specimen inhabited a calcareous worm tube; some others were found in moderately small shells, often with an associated anemone of unknown identity.

Etymology. The specific name is derived from the CSIRO research vessel Franklin, from which the species was first collected.

Distribution. Coral and Tasman Seas; New Caledonia; 285– 969 m.

Affinities. Catapagurus franklinae n. sp. appears most closely allied to C. imperialis ( Asakura, 2001) (as Hemipagurus ) and C. holthuisi McLaughlin, 1997 , in having very short ocular peduncles with prominently dilated corneas and generally long ocular acicles. However, only C. imperialis and C. franklinae share the characters of the absence of subdistal dorsal spines on the meri of the ambulatory legs in specimens exceeding shield lengths of 1.5–2.0 mm, and in the possession of a relatively small preungual process at the base of the claw of the dactyl of the fourth pereopod. Catapagurus imperialis is known only from the female holotype described from Sagami Bay, Japan, and unfortunately the sixth abdominal somite and telson are missing. However, the Japanese species appears to differ from the new species in having the dorsomesial margin of the right cheliped provided with tufts of long setae and the dorsomesial margin of the carpus of each cheliped having a row of thick spine­like setae. The merus of the right cheliped of C. imperialis is described as being armed with two large spines on dorsodistal margin, and the ischium with an acute, subdistal spine ventrolaterally, while the merus of the left cheliped is said to be armed with a large spine on the dorsodistal margin and the ischium also with an acute ventrolateral subdistal spine. Additionally, the ambulatory meri of C. imperialis each are reported to have a row of tufts of thick, long setae on the dorsal margin, the dorsodistal margin with an acute spine flanked by long, thick setae; the ventrolateral distal margin of each third merus is described as having an acute spine. Neither the described setation nor armature have been seen in any of the specimens of C. franklinae n. sp.

Figures

FIGURE 1. Catapagurus franklinae n. sp. A, holotype male 3.0 mm, R / V Franklin stn 1 – 3, (QM W 26577); B, C, paratype male 3.1 mm, R / V Franklin stn 1 – 3 (QM W 16610); D, paratype male 1.5 mm, R / V Franklin stn 46 – 3 (QM W 16609). A, cephalothorax and anterior portion of abdomen (dorsal view); B, shield and cephalic appendages (dorsal view, aesthetascs omitted); C, D, telson. Scale bars: A­C = 1.0 mm, D = 0.5 mm.

FIGURE 2. Catapagurus franklinae n. sp. A­C, E, F, paratype male 3.1 mm, R / V Franklin stn 1 – 3 (QM W 16610); D, paratype female 3.2 mm, R / V Franklin stn 1 – 3 (QM W 16610); E, paratype male 1.5 mm, R / V Franklin stn 46 – 3 (QM W 16609). A, chela and carpus of right cheliped (dorsal view); B, chela and carpus of left cheliped (dorsal view); C, D, left chela (mesial view); E, dactyl of right second pereopod (mesial view); F, left third pereopod (lateral view); G, merus of left third pereopod (lateral view). Scale bars: A­G = 1.0 mm.