Parapinnanema hawaiiensis, Semprucci, Federica & Sørensen, Martin V., 2014

Semprucci, Federica & Sørensen, Martin V., 2014, A new species of Parapinnanema (Nematoda, Chromadoridae) from Dr Theodor Mortensen’s Pacific Expedition 1914 – 16 with an identification key to the genus, Zootaxa 3881 (6), pp. 501-512 : 504-509

Parapinnanema hawaiiensis sp. nov.

( Figs. 1 , 2 , 3 ; Table 2 )

Specimens. 3 adult males; 1 adult female.

Type material. Holotype, adult male, collected by Dr Theodor Mortensen on May 5, 1915, during the Pacific Expedition 1914–1916, at 10 m depth in an unspecified coastal area of Honolulu, Hawaii, mounted for light microscopy and deposited at the Natural History Museum of Denmark ( NHMD) under accession number ZMUC NEM- 5338. Paratypes, one adult female and two adult males, collected together with holotype, mounted together on the same slide for light microscopy and deposited at the NHMD under accession number ZMUC NEM- 5329.

Etymology: The species name refers to the geographical origin.

Description of Male: Body cylindrical with blunt head and conico-cylindrical tail ( Fig. 1 A). Six internal labial sensillae in form of papillae. Six outer labial and four cephalic sensillae in a single circle, and in form of setiform papillae. Cuticle annulated and complex, battlement-like and heterogeneous, as typical for the genus ( Fig. 1 C). Annulation starts about 7 µm from the anterior end (at the level of the dorsal tooth), and is generally 3 µm thick, but thickens to 4 µm in the pharyngeal region. The cuticular annulation consists of two concentric layers of heavily sclerotized annules that are anteriorly directed on the anterior half of the body and posteriorly directed on the posterior body half. Four fields devoid of ornamentation are present in the posterior body part (two laterally, one dorsally and ventrally) ( Fig. 1 D). The non-ornamented zones are narrower anteriorly (6 µm wide) and larger in the median (14 µm) and caudal body regions (16 µm).

The cuticular sheath of the anterior end of the buccal cavity is supported by the usual twelve buccal rugae ( Fig. 1 B). The dorsal tooth is shallowly set into the wall of the buccal cavity, and is relatively large ( Figs 1 B and 3A). There are two small pointed ventral teeth and a lateral one. Amphideal fovea transverse, 12 µm wide, slit-like, located 6 µm from anterior body end ( Fig. 1 C). Diameter of amphidial fovea 0.5 of the cbd. Pharynx cylindrical, slightly enlarged posteriorly. Nerve ring at about 47% of the PL. Cardia cells not visible. Reproductive system monorchic. Male spicules arcuate (63 µm, 1.0 abd) with a small capitulum. Lateral pieces of the gubernaculum Lshaped, with the sharp flexure forming an almost exact right-angle ( Figs 1 E and 3C). The L-shaped pieces are about one-fifth the length of the spicules (41 µm). The proximal parts of the L-shaped pieces are about 1.7 the length of the distal one ( Fig. 1 E). The median piece of the gubernaculum is complex and consists of a plate with swollen distal end and is characterized by a distinct tooth ( Figs 1 E and 3C, D). It is laterally expanded and reaches the L-shaped pieces. Two differently oriented tips are also present in its distal part.

Cloacal opening surrounded by about 8 incomplete annules with a thick, protruding border ( Fig. 1 G). A cuticular elevation, 3 µm high, rises just anterior to the cloacal opening ( Figs 1 D and 3C). Anterior to the cloaca, at about 88 µm, the ventral body cuticle is modified into a distinctive raised area that comprised about 11 annules (8 µm high) ( Figs. 1 D and 3B). A morphologically similar area is present on the ventral side of the tail, but this is smaller and sometimes difficult to discern. Tail conico-cylindrical, spinneret present; non-annulated asymmetrical tail tip 18 µm long ( Fig. 1 D). No terminal setae observed.

Description of female: General appearance similar to the male. Genital system didelphic, amphidelphic with reflexed ovaries ( Fig. 2 C). Four eggs present in each branch of uterus. Musculature developed as a sphincter around the uterine chamber, with paired spermathecae. Vulva elongated extending over 11 annules; vagina open. A change of the direction of the epicuticle sculpture is observed in the vulvar region of the female ( Fig. 2 B).

Diagnosis. Parapinnanema hawaiiensis sp. nov. is a relatively slender animal (L= 2184–2250 µm, a = 33–36) with a buccal cavity which does not have a massive dorsal tooth and does have small subventral teeth, and a complex copulatory apparatus with the spicules (63–74 µm long) partially covered by the gubernaculum structure. Proximal part of L-shaped piece is about 1.7 the length its distal part. Gubernaculum very complex, with its median part forming a plate with swollen distal end and a distinct tooth. A lateral expansion starting from the distal part reaches the L-shaped pieces giving them a hump-like perception. Two tips, differently orientated, present in the proximal part of the median piece.

Differential diagnosis. Parapinnanema hawaiiensis sp. nov. is in morphologically similar to P. alii , P. bableti and P. r i t ae having similar total body length of the male and the De Man ratio values a, b and c ( Tab. 3). However, the new species differs by its lower ratios c’ and is distinguished by the presence of a lateral expansion of the median gubernaculum piece which is absent in the other species of the genus.

Species Sex n L a b c c' spic / V Distribution/Habitat alii ( Murphy, 1965) ♂ 3 1600-2000 37.6-41.0 6.2-8.5 8.2-10.3 58 Maldives, Ari Atoll; subtidal;

1800 39.5 7.2 9.5 5.1 sand; Murphy 1965 ♀ 4 1900-2050 27.2-31.5 7.1-7.9 8.5-9.8 45.3-50.7

1980 29.4 7.5 8.9 6 48.1

♂ 3 1700-2100 32.7-38.7 7.4-8.0 8.9-9.8 4.5-5.7 38-52 Western Australia, Shark Bay; 1930 36.4 7.7 9.3 5 45 sublittoral, 12 m; Inglis 1969

♀ 2 1900-2310 37-40.5 7-7.2 10-11 5.7 45.9-47.3

♀ 30 7.3 8.5 7.0 48

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Figures

FIGURE 1. Parapinnanema hawaiiensis sp. nov. A) holotype habitus; B) detail of the buccal cavity of the holotype; C) detail of the cuticular ornamentation in the cervical region of a male paratype; D) cuticular ornamentation in the middle body of the holotype; E) caudal region of the holotype; F) detail of the copulatory apparatus of the holotype; G) pattern of the cuticular ornamentation in the cloacal region of a male paratype. Scale bars: A, 100 µm; B, C, E, F, G 10 µm; D, 50 µm.

FIGURE 2. Parapinnanema hawaiiensis sp. nov., female paratype A) buccal cavity; B) detail of the change of direction (indicated by the arrows) of the epicuticle sculpture in the vulvar region; C) detail of the ovaries, eggs and vulva. Scale bars: A, 10 µm; B, 50 µm; C, 100 µm.

FIGURE 3. Light micrographs of Parapinnanema hawaiiensis sp. nov. A) buccal cavity of the holotype; B) detail of the precloacal modification of the cuticle of a male paratype; C) and D) details of the copulatory apparatus of the holotype. Scale bars: A, B, C, D, 10 µm.

Tables

TABLE 2. Morphometric measurements for Parapinnanema hawaiiensis sp. nov. (all measurements in µm, except ratios; minimum and maximum values are provided for male paratypes).

Character Holotype	Paratype 1-male	Paratype 2-male Paratype 1-female
Slide number NEM-5338	NEM-5329	NEM-5329 NEM-5329
Total length 2184	2223	2250 2259
Head diameter 22	20	21 20
Inner labial sensilla Papillate	Papillate	Papillate Papillate
Outer labial sensilla 2	2	n.v. 2
Cephalic sensilla 2	2	n.v. 2
Dorsal tooth 4	4	4 4
Subventral teeth 2	2	2 2
Distance from anterior to anterior edge of 6 amphid Amphid diameter 12	6 12	6 6 nv 14
Distance from anterior edge to nerve ring 139	134	138 105
Nerve ring cbd 55	47	51 46
Pharynx Length 294	295	282 310
Pharynx cbd 59	57	56 60
Maximum body diameter 66	66	63 75
Distance from anterior edge to vulva n/a	n/a	n/a 1092
Vulva cbd n/a	n/a	n/a 75
Distance from anterior to anus 1964	2009	2034 1994
abd 63	59	56 38
Spicules 63	65	74 n/a
Gubernaculum 33	34	31 n/a
Distance from anus to most anterior 88 supplement Tail length 220	91 214	104 n/a 216 264
a 33	34	36 30
b 7.4	7.5	8.0 7.3
c 9.9	10.4	10.4 8.5
c’ 3.5	3.6	3.9 7.0
Distance from anterior edge to vulva n/a divided by total body length s’ 1.0	n/a 1.1	n/a 0.48 1.3 n/a