Athanas alpheusophilus

Marin, Ivan, 2017, Athanas alpheusophilus sp. nov. (Decapoda: Alpheidae) - a new Alpheus - associated shrimp from the Russian coast of the Sea of Japan, Zootaxa 4324 (1): -1

publication ID

https://doi.org/10.11646/zootaxa.4324.1.3

publication LSID

lsid:zoobank.org:pub:77728C1D-430E-4B84-98Be-462E2A1F3Aaf

persistent identifier

http://treatment.plazi.org/id/6C7F0C4E-FFC2-5C6E-38DE-461CC4E9FE51

treatment provided by

Plazi

scientific name

Athanas alpheusophilus
status

 

Athanas alpheusophilus  sp. nov.

( Figs. 1–6View FIGURE 1View FIGURE 2View FIGURE 3View FIGURE 4View FIGURE 5View FIGURE 6)

Athanas japonicus Kubo, 1936  .—Marin, 2013: 61, Fig. 24–3a, b.

Material examined. Holotype: male (cl 5.6 mm, tl 11.0 mm), ZMMU Ma 5839, Russia, Sea of Japan, Posjeta Bay, Vitjaz, 42°36′7″N 131°10′43″E, depth 1–2 m, Zostera  beds, yabby pump, from burrows of Alpheus breviscristatus  , coll. I. Marin, 14 June 2015. Paratypes: 12 ovigerous females and 7 males), LEMMI, same collection data as for holotype.

Description. Small-sized shrimp with moderately slender, subcylindrical body ( Fig. 1View FIGURE 1). Carapace smooth, sparsely covered with simple erect setae ( Fig. 1View FIGURE 1). Rostrum long and slender, almost reaching distal margin of second antennular article ( Fig. 2 a, bView FIGURE 2), distally acute, without dorsal or ventral ridges, with well-marked lateral ridges ( Fig. 2 c, dView FIGURE 2). Extra-corneal and infra-corneal teeth well developed, sharp, extra-corneal slightly smaller than infra-corneal ( Fig. 2 c, dView FIGURE 2). Pterygostomial angle feebly marked, sometimes bluntly protruding ( Fig. 2 c, dView FIGURE 2). Cardiac notch well developed ( Fig. 1View FIGURE 1).

Pleomeres I –IV with ventrally rounded pleura, pleura of pleonite V with blunt posteroventral angle ( Fig. 1View FIGURE 1); pleonite VI with large subtriangular articulated plate and bluntly produced posterolateral angle ( Fig. 2 eView FIGURE 2). Telson ( Fig. 2 fView FIGURE 2) subrectangular, slightly tapering distally; dorsal surface with two pairs of stout spines, situated at about 1/2 and 1/4 of telson length, respectively; posterior margin rounded, posterolateral angle with 2 pairs of submarginal spines, the lateral spine is about 3 times shorter ( Fig. 2 fView FIGURE 2).

Eyes only partly concealed by carapace, most-posterior portion invisible in dorsal and lateral views; cornea well developed and pigmented, occupying most of eye peduncle ( Fig. 2a –dView FIGURE 2).

Antennula ( Figs. 2 a, bView FIGURE 2, 3 a, bView FIGURE 3) with antennular peduncle relatively slender; basal segment about twice longer than wide, with strong tooth on mesioventral margin, stylocerite relatively slender, acute distally, overreaching distal margin of basal antennular segment, but not reaching mid-length of second segment of antennular peduncle; latter about 0.8 times as long as basal segment, slightly longer than distal segment, about 1.5 times as long as wide in dorsal view; distal segment about 1.5 times longer than wide in dorsal view.

Antenna ( Fig. 2 a, bView FIGURE 2) with basicerite fairly stout, bearing strong, sharp ventrolateral tooth overreaching distal margin of the segment ( Fig. 2 c, dView FIGURE 2); scaphocerite subrectangular, reaching distal margin of antennular segment and distal margin of carpocerite; distolateral tooth strong, acute; distolateral tooth, convex, sloping posteriorly overreaching distal margin of scaphocerite blade ( Fig. 2 c, dView FIGURE 2).

Mouthparts typical for the genus. Maxilliped III slender, pediform; coxa with ear-shaped, distally subacute lateral plate; arthrobranch absent; antepenultimate segment about 6 times as long as wide, with a long slender subdistal spinule (or spine-like seta) on distoventral margin; penultimate segment about twice longer than wide; ultimate segment about 4.5 times as long as wide, tip furnished with long strong setae, without marked spines.

Pereiopods I (chelipeds) differ in males and females. Chelipeds relatively small, subequal and symmetrical ( Figs. 1 aView FIGURE 1, 3 cView FIGURE 3) in females, with coxa and basis unarmed, coxa with epipod; basis with minuscule rudimentary exopod; ischium about 4 times as long as wide, with unarmed margin; merus relatively slender, with straight margin, about 7 times as long as wide, slightly longer than ischium and carpus; carpus relatively short, slender, distally widening, with rows of long simple setae along distodorsal margin; palm ( Fig. 3 dView FIGURE 3) smooth, subcylindrical, with straight lateral margins, about twice longer than wide; fingers slender, subcylindrical, straight, about 4 times longer than wide, with straight cutting margins. Chelipeds greatly enlarged, subequal in size, but slightly asymmetrical in shape ( Fig. 3 eView FIGURE 3) in males, carried folded with ventral portion of palm fitting in ventrally deeply excavated merus in life ( Fig. 1 bView FIGURE 1). Major cheliped ( Fig. 5View FIGURE 5) with stout coxa and short basis, both unarmed; coxa with epipod; basis with minuscule rudimentary exopod; ischium about 2.5 times longer than wide, with single long simple spine in distodorsal angle; merus significantly broadened medially, ventral surface excavated, excavated lobe armed with several blunt small teeth along distal margin; carpus relatively slender, vase-shaped, distally widening, about 3 times longer than maximum width; palm smooth, subcylindrical, medially inflated distinctly flattened, with moderately convex dorsal and strongly convex ventral margins, without lateral teeth; polex (fixed finger) ( Fig. 5 b, cView FIGURE 5) subcylindrical, tapering and curved in distal part, with sharp tip, cutting margin with numerous small teeth, unarmed with dense rows of setae; dactylus ( Fig. 5 c, dView FIGURE 5) equal in size to polex, tapering and curved in distal part, with sharp tip, cutting margin with numerous small teeth, with well-marked large dorsal crest, outer lateral part of finger furnished with dense row of long simple setae, forming dense lateroventrally directed setal brush. Minor cheliped ( Figs. 3 eView FIGURE 3, 4 a –cView FIGURE 4) morphologically similar and only slightly smaller than major cheliped.

Pereiopod II ( Fig. 4 dView FIGURE 4) relatively slender; coxa and basis short, coxal with small epipod; basis without exopod; ischium unarmed, about 6 times as long as wide, about 1.5 times shorter than merus; merus unarmed, with straight margins, about 6 times as long as wide; carpus with 5 segments with ratio approximately equal to (proximal to distal) 4:1:1:1:2; chela simple, slender, slightly shorter that fifth carpal segment; fingers simple, as long as palm.

Ambulatory pereiopods (III –V) moderately slender. Pereiopod III ( Fig. 4 eView FIGURE 4) with short coxal segment and small epipod; basis short, as long as wide; ischium about 3 times as long as wide, with 2 small ventrolateral spines; merus unarmed, about 5.5 times as long as wide, unarmed; carpus about 4 times as long as maximal width, widening distally, unarmed; propodus about 6 times as long as wide, with 5 minute ventral spines and one pair of distoventral spinules; dactylus relatively slender, simple, curved distally, about half of propodus length. Pereiopods IV and V similar to pereiopod III, but more slender; propodus of pereiopod V armed with 2 minute spines in proximal third of length and several rows of short setae distally (propodal cleaning brush); dactylus simple, slender, slightly curved.

Uropod with exopod armed with fairly stout distolateral spine ( Fig. 2 gView FIGURE 2); diaeresis almost straight, without specific features.

Gill/exopod formula: 5 pleurobranchs (PI –V); 0 arthrobranchs; 0 podobranchs; 4 mastigobranchs (MxpIII, PI – III); 5 setobranchs (PI –IV); 3 well-developed exopods (MxpI –III) + 1 rudimentary exopod (PI).

Colour. Body and appendages deep red; white dorsal line stretching from rostral tip through mid-dorsal area of carapace to distal margin of pleomere VI; distal parts of uropodal exopod white; some small isolated white spots present on lateral surface of carapace and pleurae ( Fig. 7View FIGURE 7).

Size. Athanas alpheusophilus  sp. nov. is a relatively large species within the genus. Carapace length reaching 6.0 mm and total length about 12 mm in males, while females are slightly larger with carapace length reaching 7.0 mm and total length about 14 mm.

Ecology. All described specimens were collected from burrows of large snapping shrimp Alpheus brevicristatus  built at depths of 1–2 m into muddy sand among Zostera  beds. The species appears to be associated with A. brevicristatus  as it has never been found outside of the host burrows at the type locality or any other investigated areas along Russian coast of the Sea of Japan. Within the burrows of A. brevicristatus  , Athanas alpheusophilus  sp. nov. lives in small groups composed of several ovigerous and non-ovigerous females and one or two mature males.

Etymology. The specific name refers to the association with larger host alpheid shrimp of the genus Alpheus Fabricius, 1798  , which burrows are inhabited by the new species; from Alpheus  + philus (Greek for loving).

Distribution. Presently known only from the type locality in Vityaz Bay (42°36′7″N 131°10′43″E), Russian coast of the Sea of Japan. The species probably belongs to cold current living fauna of the Sea of Japan inhabiting northern mainland coast influenced by Liman cold current from the Sea of Okhotsk ( Fig. 7View FIGURE 7).

Taxonomic remarks. Athanas alpheusophilus  sp. nov. belongs to increasingly heterogeneous and possibly non-monophyletic “ Athanas dimorphus  ” species group (cf. Anker & Jeng 2007) characterized mainly by the general shape of enlarged chelipeds (pereiopods I), especially in males, including their ability to be carried flexed, with chela fitting in merus specially excavated for this purpose. The new species shows more close similarities with the representatives of “ Athanas japonicus  ” species group described and presently known only from Japan, including Athanas ohsimai Yokoya, 1936  , Athanas japonicus Kubo, 1940  , Athanas lamellifer Kubo, 1940  (considered as junior synonym of A. japonicus  (after Miya & Miyake 1968)).

At the same time, the new species can be clearly separated from A. ohsimai  by longer rostrum reaching the distal antennular segment (vs. reaching the midlength of second antennular segment in A. ohsimai (Yokoya 1936))  , different proportions in pereiopod I with longer carpus both in males and females (carpus of pereiopod I about half of propodal length in males ( Figs. 3 eView FIGURE 3, 4 a, bView FIGURE 4, 5 a, bView FIGURE 5) and equal to chela length in females ( Fig. 3 cView FIGURE 3)) (vs. carpus about 1/3 of propodal length in males and markedly shorter than chela in females of A. ohsimai  (Yokoya 1936: Fig. 1B, LView FIGURE 1) and different form of dactylus with marked dorsal crest ( Figs. 3 eView FIGURE 3, 4 a –cView FIGURE 4, 5 a –dView FIGURE 5) in the new species.

From A. lamellifer  the new species can be clearly separated by shorter antennal stylocerite not reaching midlength of second antennular segment (vs. overreaching distal margin of second antennular segment in A. lamellifer  (Kubo 1940: Fig. 4BView FIGURE 4)), equal in size and similar in shape pereiopods I in males (vs. unequal in size and dissimilar pereiopod I in males of A. lamellifer  (Kubo 1940: Fig. 4DView FIGURE 4, E’)), different proportions in pereiopod I with longer carpus both in males and females ( Figs. 3 eView FIGURE 3, 4 a, bView FIGURE 4, 5 a, bView FIGURE 5) (vs. carpus of pereiopod I about 1/3 of propodal length in males of A. lamellifer  (Kubo 1940: Fig. 4D, EView FIGURE 4)) and different form of dactylus with marked dorsal crest ( Figs. 3 eView FIGURE 3, 4 a –cView FIGURE 4, 5 a –dView FIGURE 5) (vs. dactylus of major pereiopod I without distal crest in A. lamellifer  (Kubo 1940: Fig. 4View FIGURE 4 D’)).

From A. japonicus Kubo, 1936  the new species can be clearly separated by different form and proportions of pereiopods I both in males and females as well as different body coloration. The new species possess large slightly unequal in size but similar in shape pereiopods I in males ( Fig. 1 bView FIGURE 1) and small similar pereiopods I in females ( Fig. 1 aView FIGURE 1) while it was indicated in the original description of A. japonicus (Kubo 1936)  that “ first pair of pereiopods robust as compared with the other legs, asymmetrical in size, usually larger in the right side than the left in both sexes, in male they are stouter than in female and slightly outreach the antennal scale ”. Such unequal and dissimilar pereiopods I in females were also described in Mya and Miyake (1968) as “Pattern II A –1” and “Pattern B” (see Mya & Miyake 1968: Fig. 5B, CView FIGURE 5), while pereiopods I characteristic for females of Athanas alpheusophilus  sp. nov. were probably indicated as “Pattern A” ( Mya & Miyake 1968: Fig. 5AView FIGURE 5); dactylus of pereiopods I in males is less than half of propodus while in Kubo’s description (1936: Pl. XIII: C, I) it significantly larger than half of propodal length. Such large dactylus is also characteristic for Athanas cf. japonicus  described by Anker (2003: Figs. 14–17) and Mya and Miyake (1968: Fig. 5FView FIGURE 5). Dactylus of both male pereiopods I in males of Athanas alpheusophilus  sp. nov. is armed with marked dorsal crest ( Fig. 3 eView FIGURE 3, 4 a –cView FIGURE 4, 5 a –dView FIGURE 5) also referred by Mya and Miyake (1968) as “Pattern IV B” ( Mya & Miyake 1968: Fig. 5GView FIGURE 5). At the same time, such significant feature is missing both in the description and figures given by Kubo (1936: pl. XIII: C, H, I) for A. japonicus  . Pattern of pereiopods I similar to the original description of A. japonicus  (Kubo, 1936: Pl. XIII C, H, I) is probably presented by Mya and Miyake (1968: Fig. F) as “Pattern IV A”. Thus, it is possible to conclude that combination of small equal-andsimilar pereiopods I in females and large unequal-and-similar pereiopods I armed with large dorsal dactylar crest in males characteristic for Athanas alpheusophilus  sp. nov. show a unique pattern within “ Athanas japonicus  ” species complex. One more feature allowing separating the new species and A. japonicus  is the body coloration. Kubo (1936) mentioned that body coloration of A. japonicus  is “ deep blue ” (Kubo 1936: 46) that is characteristic for many Athanas  species (e.g. Anker 2003), while body coloration of Athanas alpheusophilus  sp. nov. is generally deeply red ( Fig. 6View FIGURE 6).

It is also worth noting that proportions of pereiopods I in males of Athanas alpheusophilus  sp. nov. are mostly similar to A. japonicus  reported by Kubo (1936) and clearly differs from A. ohsimai  described by Yokoya (1936: Fig. 1B, LView FIGURE 1), A. lamellifer  (after Kubo 1940: Fig. 4D, EView FIGURE 4) and Athanas cf. japonicus Kubo  described by Anker (2003: Figs. 14–17). Both A. ohsimai  and A. lamellifer  can be easily separated from Athanas alpheusophilus  sp. nov. (as well as from A. japonicus  too) by significantly shorter carpus of pereiopods I in males: carpus in A. japonicus  (after Kubo 1936) and Athanas alpheusophilus  sp. nov. ( Fig. 3 eView FIGURE 3) accounting for at least half of propodal length while carpus is much shorter, not exceeding 1/3 of propodal length in Athanas cf. japonicus  (after Anker 2003), A. lamellifer  (after Kubo 1940) and A. ohsimai  (after Yokoya 1936). Male pereiopods I with long carpus were also described by Mya and Miyake (1968) as “Pattern III” ( Mya & Miyake 1968: Fig. E). Thus, Mya and Miyake (1968) synonymized A. lamellifer  and A. japonicus  using this feature incorrectly and Athanas lamellifer Kubo, 1940  could be considered as valid species until more careful and complete revision will be accomplished. Besides, some previous records of Athanas japonicus  from Indo-West Pacific (e.g. Banner & Banner 1973; Anker 2003) need to be revised.

The only Athanas  species recorded north from the latitude of the description of the new species is Athanas squillophilus Hayashi, 2002  , which can be clearly separated from the new species by longer rostrum reaching distal antennular segment (vs. reaching midlength of second antennular segment in A. squillophilus  (Hayashi 2002: Fig. 2AView FIGURE 2)) as well as shorter stylocerite, different position of dorsal spines on telson and morphology of chelipeds (pereiopods I) both in males and females (see Hayashi 2002: Fig. 3View FIGURE 3). Moreover, carpus of pereiopod II in A. squillophilus  consist of 6 segments ( Hayashi 2002: Fig. 3DView FIGURE 3) while carpus of pereiopod II consists of 5 segments ( Fig. 4 dView FIGURE 4) in the new species. By these features, A. squillophilus  seems not to be closely relative to the new species.

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Alpheidae

Genus

Athanas

Loc

Athanas alpheusophilus

Marin, Ivan 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

Athanas alpheusophilus

Marin 2017
2017
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

A. lamellifer

Kubo 1940
1940
Loc

Athanas lamellifer

Kubo 1940
1940
Loc

A. japonicus

Kubo 1936
1936
Loc

A. japonicus

Kubo 1936
1936
Loc

A. ohsimai

Yokoya 1936
1936
Loc

Athanas cf. japonicus

Kubo 1936
1936
Loc

A. ohsimai

Yokoya 1936
1936
Loc

A. japonicus

Kubo 1936
1936
Loc

A. japonicus

Kubo 1936
1936
Loc

Athanas cf. japonicus

Kubo 1936
1936
Loc

A. ohsimai

Yokoya 1936
1936
Loc

A. japonicus

Kubo 1936
1936
Loc

Athanas japonicus

Kubo 1936
1936
Loc

Athanas

Leach 1814
1814
Loc

Athanas

Leach 1814
1814