Pylopaguropsis rufilineata Komai, 2025, sp. nov.
Creators: name: Komai, Tomoyuki
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Paguridae
Pylopaguropsis
Pylopaguropsis rufilineata

description: Pylopaguropsis rufilineata sp. nov.
[New Japanese name: Kotobuki-zebra-yadokari]
(Figs. 7–11)
Material examined. Holotype: CBM-ZC 17881, female (cl 4.0 mm), off Hamahiga Island, Okinawa Islands, Ryukyu Islands, Japan, 120 m deep, 23 July 2017, baited trap, coll. K. Abe, DNA voucher.
Description. Thirteen pairs of biserial gills.
Shield (Fig. 7A) approximately as long as broad; anterolateral margins sloping; anterior margin between rostrum and lateral projections concave; posterior margin roundly truncate; dorsal surface smooth, with some tufts of short setae arranged symmetrically. Rostrum broadly triangular, terminating isp. novinule, overreaching lateral projections. Lateral projections obtusely triangular, each with small submarginal spine.
Ocular peduncles (Fig. 7A) relatively slender, 0.7 length of shield, slightly inflated proximally, with row of tufts of short setae on dorsal surface mesially; corneas not dilated, width 0.22 of peduncular length. Ocular acicles triangular, apicies acute, well separated basally.
Antennular peduncle (Fig. 7A), when fully extended, overreaching distal corneal margin by about half length of ultimate peduncular article. Ultimate article slightly broadened in dorsal view, with 2 setae at dorsolateral distal angle. Penultimate article glabrous, much shorter than ultimate article. Basal article with small spine on dorsolateral margin of statocyst lobe; ventromesial distal angle terminating in subacute tooth, but not particularly produced.
Antennal peduncle (Fig. 7A), when fully extended, reaching distal corneal margins. Fifth and fourth articles with few scattered setae. Third article with small spine at ventromedial distal angle and few setae. Second segment with dorsolateral distal angle strongly produced, well reaching beyond midlength of fourth article, terminating in bifid spine; dorsomesial distal angle with small spine. First article with 3 closely set spinules on ventrodistal margin lateral to excretely pore. Acicle barely reaching distal corneal margin or reaching midlength of fifth peduncular article, noticeably arcuate; terminating acutely, with row of individual or tufts of setae. Flagellum far overreaching tip of outstretched right cheliped by about 0.4 length; most articles each with several short and moderately long setae.
Third maxilliped (Fig. 7B, C) with moderately slender endopod. Carpus and merus unarmed. Ischium with well-developed crista dentata consisting of row of corneous-tipped spines increased in size proximally, and 1 strong accessory tooth with corneous tip. Basis with 3 corneous-tipped spines on mesial margin.
Right cheliped (Fig. 8A–E) operculate. Dactylus broad, dorsoventrally flattened, somewhat curved ventrally, set obliquely to palm, terminating into small corneous clow; surfaces with sparse tufts of short setae; dorsal surface with scattered, small, low tubercles; dorsomesial margin sharply delimited with row of closely-spaced small spines or tubercles; ventral surface gently rounded transversely, with scattered, small, low tubercles and shallow sulcus adjacent to mesial margin; occlusal margin with row of blunt teeth. Palm broad, particularly distally (1.2 times as wide as long measured along mesial margin); dorsal surface slightly convex, almost glabrous except for setae on dorsomesial margin, with scattered small spines or tubercles; dorsolateral margin distinctly delimited with irregular row of small spines or tubercles, extending onto fixed finger; dorsomesial surface rounded, with irregular rows of small spines; mesial face with sparse small tubercles and moderately long setae; ventral surface gently convex, with scattered small to moderately small, low tubercles; fixed finger broadly triangular, terminating in blunt tip bearing 2 closely set corneous spinules, with sparse tufts of setae on dorsal surface; ventral surface with scattered short setae; occlusal margin with row of low, blunt teeth in proximal two-thirds, distal one-third minutely crenulate. Carpus broader distally (1.5 times as long as distal width); dorsodistal margin with row of small spines; dorsal surface transversely convex, dorsal surface unarmed; dorsolateral margin with row of small spines or tubercles; dorsomesial margin with irregular row of small spines increasing in size distally; lateral surface with scattered small spines and tiny tubercles, mesial surface with small spines, tiny tubercles and moderately long setae on upper half; ventral surface convex, with moderately large tubercles mesially. Merus triangular; dorsodistal margin unarmed; dorsal surface smooth, almost glabrous; lateral surface with covering of coarse granules, ventrolateral margin with row of small spines or tubercles over entire length; mesial surface generally smooth but with sparse granules near ventromesial margin, ventromesial margin somewhat produced, with row of moderately large spines; ventral surface weakly produced on lateral side, with short to long setae. Ischium unarmed.
Left cheliped (Fig. 9A–D) slender, reaching base of dactylus of outstretched right cheliped; propodal-carpal articulation twisted counterclockwise approximately 30°. Chela 3.2 times as long as wide, 1.1 times as long as carpus, fingers gently bent downward, with scattered tufts of long setae on surfaces. Dactylus subequal in length to palm, terminating in small corneous claw, with scattered tufts of setae on surfaces; dorsal surface slightly rounded transversely, no spines or tubercles; occlusal margin with row of minute corneous spinules in distal half. Palm nearly parallel-sided, 1.6 times as long as broad, without armature on surfaces; fixed finger with occlusal margin bearing row of minute, sharp calcareous teeth, terminating in 2 contiguous corneous claws. Carpus broadened distally in dorsal view, 3.2 times as long as distal breadth; dorsomesial margin with row of small spines and tufts of long setae; dorsolateral margin not clearly delimited, but with few small spines or tubercles and tufts of long setae; lateral surface with long setae dorsally, almost glabrous ventrally; mesial face nearly flat, with long setae dorsally and ventrally; ventral surface with numerous setae. Merus dorsal surface with few short setae; lateral surface with scattered granules, ventrolateral margin with row of strong spines on distal half; mesial face almost glabrous, ventromesial margin with 1 small spine far remote from distal angle, followed by small, low protuberances; ventral surface with numerous long setae. Ischium unarmed; ventral surface with several long setae.
Second pereopods dissimilar from right to left with left shorter than right, but left in process of regeneration, not normal in development. Right second pereopod (Fig. 10A–C) with dactylus 1.2 length of propodi, 7.5 times as long as broad, slightly curved ventrally in lateral view, almost straight in dorsal view, terminating in moderately large corneous claw; dorsal margin with row of tufts of stiff setae, ventral margin with 9 corneous spines; lateral surface slightly convex, with some setae adjacent to dorsal margin; mesial surface with row of 5 corneous spinules adjacent to dorsal margin in distal half. Propodus slightly arcuate, with row of tufts of setae on dorsal margin; lateral and mesial faces almost glabrous; ventral margin with sparse very short setae, ventrodistal margin with 1 corneous spinule. Carpus with small dorsodistal spine, dorsal surface without spines but with sparse stiff setae. Merus with row of setae on dorsal and ventral margins, ventrolateral distal margin with minute subdistal spine; lateral and mesial surfaces glabrous, former with minute granules adjacent to ventral margin. Ischium unarmed, setae on dorsal margin.
Third pereopods (Fig. 11D–H) slightly dissimilar and unequal in length (right 1.2 times as long as left). Dactyli 1.3 (right) or 1.4 (left) length of propodi, 6.7 (right) or 7.0 (left) times as long as broad, right slightly broader than left, slightly curved ventrally in lateral view, almost straight in dorsal view, terminating in large corneous claw; dorsal margin with row of stiff setae, ventral margin with 10 (left) or 13 (right) corneous spines; lateral surface slightly convex in left, having faint longitudinal sulcus proximally in right, with some setae adjacent to dorsal margin; mesial surface with row of 8 (left) or 9 (right) corneous spinules adjacent to dorsal margin and additional row of 4 corneous spinules along ventral margin (right). Propodi slightly arcuate, with row of stiff setae on dorsal margins; lateral and mesial surfaces almost glabrous, no sculpture on flattened right lateral surface; ventral margins with sparse very short setae, ventrodistal margins each with 1 corneous spinule. Carpi with only small dorsodistal spine, dorsal surface with sparse setae. Meri with row of individual or tufts of setae on dorsal and ventral margins, ventrolateral distal margin unarmed; lateral and mesial surfaces glabrous. Ischium unarmed, setae on dorsal and ventral margins. Paired gonopores on coxae.
Fourth pereopods (Fig. 7D) with minute preungual process on dactylus, about half length of long claw. Propodal rasp of 2 rows of corneous scales extending to proximal 0.25 of ventral margin). Carpus without dorsodistal spine.
Fifth pereopods chelate.
Third thoracic sternite unarmed. Sixth thoracic sternite (Fig. 7E) with broadly rounded anterior lobe, bearing transverse row of setae. Eighth thoracic sternite (Fig. 7F) vertically compressed, divided in 2 blunt lobes.
Pleon (Fig. 11) dextrally twisted, with paired first pleopods consisting of 2 articles (Fig. 7F), distal article longer than proximal article, with some distal setae. Unpaired left second to fifth pleopods present. Uropods markedly asymmetrical.
Telson (Fig. 7G) with deep lateral indentation; posterior lobes as broad as anterior lobes, strongly dissimilar, separated by shallow, narrow median cleft; terminal margins oblique, left with row of several spinules not extending to lateral angle (tip of left posterolateral angle strongly folded), right with row of some spinules not extending to lateral angle; lateral margins unarmed.
Colouration in life. Fig. 11. Carapace mottled with light orange, with pair of red blotches posterior to base of ocular peduncles; anterior part of branchiostegite with longitudinal stripes of bright red and white. Ocular peduncles pale purple, without distinct markings; cornea yellow-gray. Antennular peduncles pale purple without markings, flagella white. Antennal peduncles generally light orange; second article with red longitudinal stipes on dorsal and lateral surfaces; fourth article with red longitudinal stripe on lateral face; fifth article with red longitudinal stripes on lateral and mesial margin; flagellum purplish. Right cheliped with chela and carpus generally light brown, with scattered darker spots on dorsal surface; chela with red longitudinal stripe on mesial face; carpus with median red stripe flanked by white stripes on mesial face; merus dorsal surface with red stripe, lateral face with broad red stripe flanked by white stripes on upper half, mesial face with large red patch flanked by white stripes and traversed medially by white stripe, lower part reddish. Left cheliped palm with white median stripe flanked by red stripes on each dorsal and ventral surface; dactylus with red stripes on dorsal and ventral surfaces, flanked mesial face white; carpus and merus alternated by red and white stripes. Ambulatory legs with longitudinal red and white stripes on dactyli to meri; dactyli and propodi dorsal and ventral margins white, on lateral face, 2 red stripes flanking white median stripe present; carpi with 3 red and 2 white stripes on lateral faces; meri dorsal surfaces red, lateral faces each with 3 white and 2 red stripes; ischia dorsal margins white, with 1 red stripe on upper half on lateral faces. Fourth and fifth pereopods generally light yellow-brown. Pleon light yellow-brown.
Distribution. Presently known only from the type locality, off Hamahiga Island, Okinawa Islands, at depth of 120 m.
Genetic data. COI (LC833903), 16S rRNA (LC834108).
Remarks. Pylopaguropsis rufilineata sp. nov. does not exhibit appreciable structural modifications in the right third pereopod, although the propodus is slightly broader than that of the left third pereopod and has a flat lateral surface. In this regard, it is comparable to species of the P. teevana group (McLaughlin & Haig 1989). Within the species referred to the P. teevana group, the new species is most similar to P. pustulosa, sharing the following features: right chela operculate, with evenly convex ventral surface; left cheliped palm unarmed; lateral surface of right third pereopod propodus nearly flat; and propodal rasp of fourth pereopod consisting of two rows of corneous scales. The present new species is readily distinguished from P. pustulosa by the following particulars: (1) the right cheliped dactylus is fairly compressed, armed with a single row of small spines delimiting the dorsomesial margin, and with some tiny, low tubercles on the mesial and ventral surfaces in P. rufilineata sp. nov. (Fig. 8A–D), whereas the dactylus is not particularly compressed, armed with irregular double row of very small blister-like tubercles on the dorsomesial margin, and with numerous blister or pimple-like small tubercles or granules on the mesial and ventral surfaces in P. pustulosa (cf. McLaughlin & Haig 1989: figs. 8c, 10b); (2) the dorsolateral margin of the right chela is delimited by a single row of small blunt or spiniform tubercles on over the entire length in P. rufilineata sp. nov. (Fig. 8B, C), rather than delimited by double row of small tubercles only on the fixed finger in P. pustulosa (cf. McLaughlin & Haig 1989: 160, fig. 8c); (3) the dorsal surface of the right palm bears scattered small spines in P. rufilineata sp. nov. (Fig. 8C), whereas there are only a few, scattered very tiny tubercles on that surface in P. pustulosa (cf. McLaughlin & Haig 1989: fig. 8c); (4) the ventromesial margin of the right cheliped merus is armed with a row of strong spines in P. rufilineata sp. nov. (Fig. 8A), instead of a few spinules in P. pustulosa (McLaughlin & Haig 1989: fig. 10b); (5) the posterior lobes of the telson are more strongly asymmetrical and more weakly armed on the terminal margins in P. rufilineata sp. nov. than in P. pustulosa (Fig. 7G versus McLaughlin & Haig 1989: 13 h). The living colouration is unknown for the holotype of P. pustulosa (McLaughlin & Haig 1989: 161), but later a colour photograph of a specimen in fresh condition from Taiwan has been published (McLaughlin et al. 2007). The colour of the ocular peduncle is particularly different between P. rufilineata sp. nov. and P. pustulosa: in the new species, the ocular peduncle is uniformly pale purple (Fig. 11), whereas it has red and white stripes in P. pustulosa (McLaughlin et al. 2007: 191, unnumbered fig.).
Etymology. From the combination of the Latin rufus (= red) and lineatus (= lined), referring to the striped color pattern of the chelipeds and ambulatory legs of the new species.
description: Published as part of Komai, Tomoyuki, 2025, Two new species of the pagurid hermit crab genus Pylopaguropsis Alcock, 1905 (Decapoda: Anomura) from Japan, pp. 315-334 in Zootaxa 5620 (2) on pages 324-330, DOI: 10.11646/zootaxa.5620.2.6, http://zenodo.org/record/15219627