Hansenocaris papillata, Kolbasov & Grygier & Ivanenko & Vagelli, 2007
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publication ID |
https://doi.org/ 10.5281/zenodo.5333896 |
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publication LSID |
lsid:zoobank.org:pub:BC56DD73-E060-47B6-90CE-75F3E7C4C256 |
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persistent identifier |
https://treatment.plazi.org/id/03B48793-0D70-FFC9-D1F4-FDB1FC00FA03 |
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treatment provided by |
Diego |
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scientific name |
Hansenocaris papillata |
| status |
sp. nov. |
Hansenocaris papillata , new species
( Figs. 1–4 View Fig View Fig View Fig View Fig )
Material examined. – Holotype: One y-cypris in the gut of the fish Pterapogon kauderni Koumans, 1933 (Teleostei, Apogonidae ) (size: SL = 24 mm, TL = 40.5 mm, sex = male), collected by A. A. Vagelli with hand nets using SCUBA and preserved immediately in alcohol. Collection date: 3 Feb. 2001. Type locality: off Masoni [= Island], Banggai [=Archipelago], eastern Indonesia (01º45'56.7"S 124º08'48.5"E), depth 2.2 m. The holotype mounted on an SEM stub is deposited in the Zoological Museum of Moscow State University (no. Mg. 1213). A CD-ROM containing all the digital SEM photographs that were taken of the specimen has also been deposited there for permanent reference.
Diagnosis. – Y-cyprid with short head shield, its anterior end slightly produced and its posteriolateral ends not reaching the abdomen; pair of conspicuous ventral papilliform protrusions at anterior end of head shield (the clearest autopomorphy of the species); antennules with conspicuous, curved claw; pleural extensions of thoracomeres 5 and 6 of trapezoidal shape; abdomen four-segmented, first three segments lacking pointed posterioventral extensions (square posterioventral corners in the first two) and third segment small; telson with serrate spines along posterioventral margin.
Etymology. – From the Latin papillatus – budlike, refering to the pair of papilliform protrusions at the anterior end.
Description. – General appearance: the body consists of a head, a six-segmented thorax and a four-segmented abdomen ( Fig. 1 View Fig ). The total length is approximately 340 µm. The head shield (or carapace) covers the head and the anterior part of the thorax, although it is free from the latter. The small nauplius eye lies dorsally to the pair of large compound eyes. It was impossible to trace in detail the number and positions of the ommatidia of the compound eyes. The labrum and antennules are situated on the ventral side of the head, under the compound eyes. Each thoracic segment bears a pair of biramous thoracopods. The fourth abdominal segment or telson is the largest and it terminates in a pair of furcal rami.
Head shield ( Figs. 1 View Fig , 2 View Fig , 3A, B View Fig ): the short, univalved head shield only partially covers the dorsal and lateral sides of the larval body, with the shield’s lateral sides extending to the fourth thoracic segment ( Figs. 1 View Fig , 2A, B View Fig ). This shield resembles an inverted boat with the posteriolateral parts somewhat produced, about 215 µm long along the mid- dorsal line and 240 µm along the lateral margins. Long longitudinal, short transverse and oblique cuticular ridges outline ‘plates’ that occupy the anterior and lateral sides of the head shield, whereas the mid-dorsal area possesses indistinct longitudinal ribs only. A conspicuous narrow groove, 18 µm long, is situated along the mid-dorsal line in the centre of the head shield ( Fig. 2B View Fig ). The surface of the head shield bears numerous pores and pore-like pits in a symmetrical pattern ( Fig. 2B View Fig ), comprising three major types. The first type has a slit-like, somewhat puckered opening enclosed by a conspicuous circular rim ( Figs. 2E View Fig , 3A, B View Fig ). The second type is a deep pit with a round mouth from which a single short seta protrudes ( Figs. 2 View Fig , 3A View Fig ). The third type are small paired pores (including the terminal pores of the lattice organs) and bigger unpaired, so-called central pores (cp), all with round mouths and possessing neither a cuticular rim nor a seta ( Fig. 2 View Fig ). There are at least three of these unpaired central pores in the mid-dorsal line, two situated anteriorly and one posteriorly ( Figs. 2B–F View Fig ). A pair of unusual papilliform protrusions is located at the anterior end of the cypris, arising ventrally from the lateral margins of the head shield ( Figs. 1 View Fig , 2A View Fig , 3A, B View Fig ). They are about 7 µm long, converge slightly towards their distal ends and have a round opening at the tip.
Lattice organs ( Figs. 2B–F View Fig ): we found four pairs of lattice organs (lo) on the surface of the head shield, situated near the mid-dorsal line and grouped into two anterior and two posterior pairs. The anterior pairs (lo1 and lo2) are demarcated from the general cuticle by a weak depression and as a group surround the most anterior of the unpaired central pores 30–40 µm from the anterior end of the head shield ( Figs. 2B–D View Fig ). The cuticle of the lattice organs is smooth and lacks any trace of small pores comprising a pore field. The first pair (lo1) have a teardrop-like form about 6.7 µm long and 2.7 µm wide; they converge strongly anteriorly and each narrows posteriorly towards the small terminal pore ( Fig. 2D View Fig ). The second pair (lo2) are elongate, 14 µm long and about 2 µm wide; they converge anteriorly and each narrows weakly towards the tiny, posterior terminal pore ( Fig. 2D View Fig ).
In our specimen we have not found the usual third pair of lattice organs, which in H. itoi normally sits in front of the posterior unpaired central pore (Høeg & Kolbasov, 2002). The posterior pairs of lattice organs (lo4 and lo5) are situated near the most posterior central pore and lie within conspicuous, posteriorly tapered, cuticular ridges or keels ( Figs. 2E, F View Fig ). They do not possess visible terminal pores, but their shape indicates a posterior position for the pore of each. The lo4, each about 8 µm long and 2 µm wide, converge anteriorly whereas the lo5, each about 12 µm long and 3 µm wide, converge weakly anteriorly.
Antennules ( Figs. 1 View Fig , 3A, C, D, G View Fig ): the antennules are covered by shrunken cuticle, which hides all traces of segmentation ( Fig. 3C View Fig ). Their distal parts bear a conspicuous curved hook (‘claw’), a corrugated aesthetasc, and a single seta ( Figs. 3C, D View Fig ).
Other cephalic structures: the distal part of the labrum has one anterior and four posterior prominent hooks ( Figs. 1 View Fig , 2A, G View Fig ). We did not find vestiges of antennae or mandibles, nor any trace of a pair of bifurcate paraocular processes associated with the compound eyes or a pair of postocular filamentary tufts situated more posteriorly.
Thorax and thoracopods ( Figs. 1 View Fig , 2A View Fig , 3A, E–G View Fig , 4A, B View Fig ): the thorax consists of six segments ( Figs. 1 View Fig , 4A View Fig ) with serrate posterior margins ( Fig. 4B View Fig ). We could not determine whether the tergites of the first two segments were dorsally fused (cf. Grygier, 1987). Each tergite is also equipped with two or three transverse, serrated cuticular ridges ( Figs. 4A, B View Fig ). The tergites of the fifth and sixth thoracic segments have trapezoidal pleural extensions with sharp posterior ends ( Figs 3F View Fig , 4A, C View Fig ). Each thoracomere bears a pair of biramous thoracopods.
Each thoracopod consists of a basal array of sclerites, a coxa, a basis, and a pair of rami (exopod and endopod). The first limb has two-segmented endo- and exopods, each with a short proximal segment lacking armament and an elongate distal segment bearing two terminal setae ( Figs. 3A, E, G View Fig ). The distal segment of the exopod has a short outer seta and a long inner seta whereas the endopod bears two long setae ( Fig. 3E View Fig ). The exopods of the remaining thoracopods (2–6) are two-segmented as in the first pair, but they have three, instead of two, terminal setae: one short outer seta and two long middle and inner setae ( Figs. 3E–G View Fig ). The endopods are all three-segmented; the second segment has a single long inner seta on its distal end while the distal segment bears two long terminal setae. The protopod of thoracopod 6 is shorter than the others and appears unsegmented ( Fig. 4A View Fig ).
Abdomen ( Figs. 1 View Fig , 2A View Fig , 4A, C–E View Fig ): the abdomen consists of three short segments and a long telson with furcal rami. The third segment is the shortest, tapering ventrally and intercalated between the second segment and the telson ( Fig. 4A View Fig ). The abdominal segments have serrate margins, and the first and second segments have quadrangular pleural extensions with sharp posterioventral corners. The telson is densely covered by serrate, ridges that outline two dorsal and two lateral longitudinal rows of ‘plates’, whereas the ventral face lacks such ridges (we did not notice any conspicuous sculpture on the ventral face). Four pairs of lateral pores are present on the telson, two at the anterior end ( Fig. 4C View Fig ) and two near the furcal rami ( Fig. 4D View Fig ). Five conspicuous and serrate terminal spines project along the posterioventral border of the telson ( Figs. 4C–E View Fig ).
A pair of short, unsegmented furcal rami is inserted in the posterior end of the telson ( Figs. 4C, D View Fig ). Each ramus carries three wide, lanceolate setae of different lengths, with serrate margins.
Comparison. – The anterior papilliform protrusions, the short head shield, and the lack of pointed posterioventral extensions of the first three abdominal segments are the most distinctive characteristics of H. papillata .
Six of the 11 previously described facetotectan species were established on the basis of y-cypris characters (Table 1), the other five on the nauplius y phase. The first of the latter, Proteolepas hanseni , was described from the Adriatic Sea based only on a single instar ( Steuer, 1905). Later, Itô (1985) referred to this species as Hansenocaris hanseni ( Steuer, 1905) , new combination. It displays characters of both naupliar types I and IV of Hansen (1899), and therefore H. hanseni remains a species of dubious recognition (Kolbasov & Høeg, 2003). Recently, four more facetotectan species were described on the basis of naupliar instars from Mediterranean coastal waters of the Salento Peninsula in southeastern Italy ( Belmonte, 2005): H. corvinae , H. leucadea , H. mediterranea , and H. salentina . Although these species are readily distinguishable from one another, none are linked to any form of cypris y and none can be compared directly to previously described nominal species of Hansenocaris that are based on the cypris stage. Along with H. hanseni , these Mediterranean y-nauplii represent the beginning of a parallel nomenclature, which, although perhaps inevitable given the availability of material, may in time prove to be an impediment.
All the main characters of the described facetotectan species for which the y-cypris stage is known are listed in Table 1. Hansenocaris papillata differs distinctly from all the other species by the presence of a pair of conspicuous, ventrallydirected, papilliform protrusions at the anterior end. It also can be easily distinguished from the Atlantic y-cyprids, including H. itoi , and some of the Pacific species (i.e. H. pacifica and H. furcifera ) in having a relatively shorter head shield, which does not reach the abdominal segments, as well as a shorter total length, approximately 340 µm for the new species instead of 425–590 µm for the other species (Itô & Ohtsuka, 1984; Itô, 1989; Kolbasov & Høeg, 2003). The three unpaired central pores along the mid-dorsal line of H. papillata may represent gland openings and correspond to pores cp2, cp3 and cp4 found in the cypris y larva of H. itoi (Høeg & Kolbasov, 2002; Kolbasov & Høeg, 2003). The most anterior of these pores is surrounded by the anterior two pairs of lattice organs in our specimen, as is true for cp 2 in H. itoi . The single posterior central pore in both of these forms of cypris y is presumably mutually homologous. Hansenocaris papillata is comparable in length with H. rostrata , H. acutifrons and H. tentaculata (335–375 µm) (Itô, 1984, 1985, 1986b). These species also have a rather short head shield, but differ from the new species in other characters. They all reportedly lack an antennular claw or hook, whereas H. papillata has a well developed antennular claw. In most other forms of cypris y the antennules consist of four segments, the second segment being armed with a hook and sometimes with a minute lateral seta, the third segment bearing one or two lanceolate setae, and the small fourth segment carrying a subterminal aesthetasc and one long and one short terminal setae ( Grygier, 1987; Kolbasov & Høeg 2003). Not all of the elements of the distal two segments were confirmed as being present in our specimen.
The anterior end of the head shield of H. rostrata and H. acutifrons is strongly produced in comparison with the slight elongation in H. papillata . In addition, H. acutifrons has six serrate spines along the posterioventral border of the telson (five in H. papillata ) while H. tentaculata lacks such spines.
The segmentation and setation of the thoracopods in H. papillata correspond completely with the situation in the Atlantic y-cyprids, including H. itoi (see Bresciani, 1965; Schram, 1970a; Grygier, 1987; Kolbasov & Høeg, 2003) and H. furcifera (cf. Itô, 1989). All have a two-segmented endopod in thoracopod 1 and three-segmented endopods in thoracopods 2–6. In contrast, all thoracopods of H. acutifrons , H. pacifica and H. rostrata , and thoracopods 3–6 of H. tentaculata possess only two-segmented endopods ( Itô, 1985, 1986b), with a seta in the middle of the distal endopodal segment. The segment boundaries are all clear and represent movable articulations. Following Schram (1970a), Grygier (1987) and Kolbasov & Høeg (2003), we agree that this seta corresponds to the seta on the second endopodal segment in y-cyprids with three-segmented endopods and that either the two distal segments of the endopod are fused in Itô’s specimens or he missed an imperfectly displayed segment border.
The two posterior pairs of pores on the telson have not been reported before in other species, but they may have been overlooked.
Hansenocaris papillata is the first facetotectan species reported from the tropical waters of Indonesia. All earlier named species of cypris y have been described from warmtemperate (Kuroshio Current-influenced) waters of Japan ( H. pacifica , H. rostrata , H. acutifrons , H. tentaculata and H. furcifera ) or boreal waters of the White Sea ( H. itoi ). Other unnamed y-cyprids have been found in boreal waters of the North Atlantic ( Bresciani, 1965; Grygier, 1987), tropical waters of the Bahamas ( Schram, 1970a), tropical waters of the Gulf of Aqaba (Eilat, Red Sea) (Almeida Prado-Por & Por, 1988) and in Japan including Okinawa ( Grygier, 1997; unpublished data).
In total length and in terms of the size and form of the head shield, H. papillata is similar to the abovementioned y-cypris from the Gulf of Aqaba (Almeida Prado-Por & Por, 1988). Unfortunately, these authors did not describe the morphology of their specimen, providing only a single light micrograph. Itô (1991) presented a drawing in dorsal view of an undescribed cypris y he raised though its naupliar series in the laboratory. As in H. papillata , the head shield is short and ornamented with a preponderance of longitudinal cuticular ridges. The visible dorsal ornamentation of the posterior thorax and abdomen is also consistent with that of H. papillata , but in the absence of information concerning its cephalic structures, appendages, etc., we can only suggest that Itô’s form may be related to our new species. A relatively short-shielded, undescribed cypris y from Japan shown in side view by SEM by Grygier (1997) is, despite the small size of the image, readily distinguished from H. papillata by several features: a considerably greater length to height ratio of the head shield, rounded rather than protruding and pointed posterioventral corners of the shield, no sharp posterioventral protrusion of the pleural expansions of thoracomere 5, and at least one more ‘plate’ in each lateral plate row on the telson.
Remarks. – As mentioned before, the description of this species was done by the first two authors and this species should be cited hereafter as Hansenocaris papillata Kolbasov & Grygier, 2007 .
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