Duplominona puertoricana Curini-Galletti, 2019

Curini-Galletti, Marco, Stocchino, Giacinta A. & Norenburg, Jon L., 2019, New species of Duplominona Karling, 1966 and Pseudominona Karling, 1978 (Platyhelminthes: Proseriata) from the Caribbean, Zootaxa 4657 (1), pp. 127-147 : 138-141

Duplominona puertoricana Curini-Galletti n. sp.

( Fig. 6 D, E, G, I, J )

Holotype. Puerto Rico: Cayo Corral , off Isla Magueyes (Lat. 17.936739, Lon. -67.019831), at about 10 cm of depth, in poorly sorted granule, December 1988: original film and printed pictures of the copulatory structures (SMNH- Type 9182).

Other material. Same data as holotype, two specimens observed alive, and used for karyology.

Etymology. The species is named after the geographical area of finding.

Description. A rather robust Duplominona : living specimens about 2 mm long ( Fig. 6 E ).

Male genital system. With 8–12 testes, arranged into a single, median row. Copulatory organ very elongate, about 270 μm long, with a long and tubular prostatic vesicle. The proximal half of the cirrus is devoid of spines ( Fig. 6 D ). The spiny area of the cirrus, which extends for a length of about 75 μm, is formed by numerous (about 50) rows of mostly minute, very densely packed spines, which change continuously in shape and size along the length of the cirrus ( Fig. 6 I, J ). Proximally, spines are poorly sclerotised, acutely triangular, up to 6 μm long. They become progressively smaller distally, to about 2 μm. In the median area of the cirrus, spines are more sclerotized, with a curved distal tip, and with wider, bilobed bases. These spines become gradually longer, to 3 μm, scale-like, with smaller curved tips. These latter are followed distally by an area of very small, triangular spines, about 1 μm long. Distalmost spines are slightly longer, to 2/2.5 μm, and very fine and slender.

Accessory organ provided with a stylet about 19 μm long; it opens through its own pore. Female genital system. Ovaria and vitellaria as in previous species. In none of the specimens observed the presence of a bursa or a vagina could be noticed. Female pore opens posteriorly to prostatoid organ pore.

Karyotype. With n=3, and basic karyotype ( Curini-Galletti & Martens, 1990). Chromosome pairs I and II markedly differing in length ( Fig. 6 G ). Karyotype formula: FN=5; Chromosome I: 48.63 ± 3.37; 44.76 ± 1.55 (m); Chromosome II: 35.49 ± 3.07; 46.48 ± 2.54 (m); Chromosome III: 16.06 ± 2.18; 10.43 ± 4.11 (a) (based on 10 plates).

Diagnosis. Species of Duplominona with up to 12 testes in one row. Cirrus very elongate, spiny in its distalmost half only. Proximal spines poorly sclerotized, to 6 μm long. Spines become smaller and more curved medially, with bilobed bases; distalmost spines are more slender, to 2.5 μm long. Accessory stylet about 19 μm long. Bursa-vagina system not observed. Karyotype with two pairs of metacentric and one pair of smaller heterobrachial chromo- somes.

Remarks. With the addition of the new species described here, the genus Duplominona includes 35 taxa, and is one of the most species-rich among Proseriata (Tyler et al., 2006–2016; 2006–2018). Diagnoses of most species are based on details of the sclerotized structures of the cirrus only (see, i.a., Martens & Curini-Galletti, 1989): therefore, we have largely based the taxonomic key (Tab. 1) on the morphology of cirrus spines. On this basis alone, all of the new species may be discriminated from congenerics. Duplominona diademata n. sp. stands out for the unique morphology of its cirrus—no other species in the genus, in fact, has two distinct blocks of spines ( Fig. 5 F, G ). Duplominona aduncospina n. sp., with a cirrus provided with few spines all alike, and with a unique morphology ( Fig 1 B, C ), is a further peculiar species, quite distinct from congenerics. Distinction among the rest of the species is based on the patterns of morphology of spines, which varies along the length of the cirrus. In D. pusilla n. sp. and D. bocasana n. sp. proximal and distal spines are different, and they may be distinguished between them and from the Brazilian D. mica Marcus, 1951 , the only other species with the same pattern, based on size and morphology of spines ( Figs 3 B , 4 G–H; Curini-Galletti, 2014: Fig 2 C ; Tab. 1).

Duplominona macrocirrus n. sp. is the only species in the genus in which proximal and distal spines are similar in morphology, and median spines are distinctly longer and straighter ( Fig. 6 B, C ). In D. dissimilispina n. sp., D. chicomendesi n. sp. and D. puertoricana n. sp., proximal, median and distal spines have different morphologies, and the three species are easily distinguished based on size and morphology of spines ( Figs 4 B, D, F, G ; 5 B, C ; 6 I, J ; Tab. 1). Duplominona dissimilispina n. sp. is particularly striking, as no other species of the genus has comparably long, needle-like spines.A tripartite tail is only known in D. terdigitata n. sp. and D. tridens (Marcus, 1954) from Brazil (see discussion below): these can be discriminated based on the different morphology of cirrus, and number of spines: D. tridens shows in fact a single row of few, recurve spines ( Fig. 2 C ; Curini-Galletti, 2014: Fig. 3 A ).

It is worth noting that only one Duplominona was previously known from the Greater Caribbean area: D. canariensis bermudiensis Ax & Sopott-Ehlers, 1985 , from Bermuda Is., with a common male+vagina pore, and a cirrus provided with very small triangular spines ( Ax & Sopott-Ehlers, 1985). Although a number of the new species described here have vagina and male pores in close proximity, in none a fusion of the two pores has been observed, nor do any of the new species have such minute spines, evenly distributed along the length of the cirrus. The nominal subspecies D. canariensis canariensis Ehlers & Ehlers, 1980 was based on specimens from Gran Canaria (Canary Islands), and is supposed to be distinct for an overall larger size and larger spines, up to 2 μm in length ( Ehlers & Ehlers, 1980, Tab. 1). Given the wide geographic separation, and the morphological differences, it may be questioned whether the subspecies status may apply to the Bermudian population, or it may rather deserve a full species recognition. In any case, it is not comparable to the new species here described. For the distinction of the new species from the other Western Atlantic species, all from south Brazil ( D. tridens , D. mica , D. brasiliensis Curini-Galletti, 2014 ) see the discussion above and the identification key (Tab. 1).

TABLE 1. Taxonomic key for species of the genera Duplominona and Pseudominona . Species described in the present paper are in bold.

1 - tail tripartite......................................................................................... 2

- tail undivided........................................................................................ 3

2 - ovaria prepharyngeal.................................................................................. 4

- ovaria postpharyngeal.................................................................................. 5

4 - cirrus with one row of spines; South Brazil................................... .. Duplominona tridens (Marcus, 1954)

- cirrus with 15 rows of spines or more; Caribbean................................. Duplominona terdigitata n. sp.

5 - cirrus long and narrow, vagina posterior to copulatory organ; Caribbean........... Pseudominona dactylifera Karling, 1978

- cirrus short and broad, vagina anterior to copulatory organ; Caribbean................ Pseudominona cancan n. sp.

3 - cirrus provided with a stylet............................................................................. 6

- cirrus without a stylet.................................................................................. 7

6 - cirrus without spine................................................................................... 8

- cirrus with spines..................................................................................... 9

8 - stylet ≈27 μm; accessory organ and male pores fused; Indonesia......... Duplominona axi Martens & Curini-Galletti, 1989

- stylet 32-36 μm, accessory organ and female pores fused; Galapagos............... Duplominona sieversi Ax & Ax, 1977

9.- stylet very long, 100 μm or more........................... Duplominona samalonae Martens & Curini-Galletti, 1989

- stylet short, 70 μm or less.............................................................................. 10

10 - stylet narrowing abruptly distally; Galapagos................................. Duplominona krameri Ax & Ax, 1977

- stylet not as above................................................................................... 11

11 - stylet narrow (ratio length/width> 6)..................................................................... 12

- stylet broad (ratio length/width <3)...................................................................... 13

12 - stylet 45 μm long, spines 2 μm long; Galapagos.......................... Duplominona galapagoensis Ax & Ax, 1977

- stylet 70 μm long, with many rows of spines 7 μm long; Japan........................ Duplominona japonica Ax, 2008

- stylet 60 μm long, 3 rows of spines 7–8 μm long; N.W. USA............. Duplominona stilifera Sopott-Ehlers & Ax, 1985

13 - stylet 35 μm; 25 rows of spines 2–5 μm long; S. Brazil.................. Duplominona brasiliensis Curini-Galletti, 2014

- stylet 23 μm, about 10 rows of spines 3–3.5 μm; Galapagos....................... Duplominona karlingi Ax & Ax, 1977

- stylet 25 μm; 4–6 rows of spines 6–8 μm long; North Sea................... Duplominona septentrionalis Martens, 1983

7 - cirrus with one girdle of spines......................................................................... 14

- cirrus with numerous girdles of spines.................................................................... 15

14 - spines acutely triangular, 2–3 μm long; Indonesia............... Duplominona muslimini Martens & Curini-Galletti, 1989

- spines broad, 5–6 μm long, with recurve apex, Mediterranean................... Duplominona paucispina Martens, 1984

15 - spiny area of cirrus continuous.......................................................................... 16

- spiny area separated into two distinct blocks; Caribbean........................... Duplominona diademata n. sp.

16 - cirrus spines all alike or only slightly different............................................................. 17

- cirrus spines markedly different......................................................................... 18

17 - with a long vaginal duct surrounded by strong muscles; Macquarie Is............ Duplominona amnica (Ball & Hay, 1977)

- vaginal duct not as above.............................................................................. 19

19 - spines densely packed, very small, needle-shaped; Mediterranean................. Duplominona istambulensis (Ax, 1959)

- spines nearly equilateral, apex markedly downturned; Caribbean................ Duplominona aduncospina n. sp.

- spines triangular, much higher than wider................................................................. 20

20 - cirrus> 60 μm and narrow............................................................................. 21

- cirrus <40 μm and broad.............................................................................. 22

21 - spines 0.5 μm long; Mediterranean........................................ Duplominona longicirrus Martens, 1984

- spines 3–5 μm long, Indonesia.......................... Duplominona makassariensis Martens & Curini-Galletti, 1989

22 - with few (about 10) rows of spines...................................................................... 23

- with numerous (>20) rows of spines..................................................................... 24

23 - spines 5 μm long; N. Japan.................................................... Duplominona filiformis Ax, 2008

- spines 1–1.5 μm long; Mediterranean....................................... Duplominona corsicana Martens, 1984

24 - cirrus 25 μm long, spines 1 um long; Bermuda.......... Duplominona canariensis bermudiensis Ax & Sopott-Ehlers, 1985

- cirrus 35 μm long, spines 2 um long; Canary Is.............. Duplominona canariensis canariensis Ehlers & Ehlers, 1980

- cirrus 35 μm, spines 4 μm long; Indonesia.................. Duplominona sulawesiensis Martens & Curini-Galletti, 1989

18 - spines similar in shape, but differing in length.............................................................. 25

- spines different in morphology and length................................................................. 26

25 - cirrus short, <10 rows of spines proximally 7 μm, distally 3 μm long; N. Australia..................................................................................... .. Duplominona darwiniensis Martens & Curini-Galletti, 1989

- cirrus short, ≈ 15 rows of spines proximally 18 μm, distally 10 μm long; Hawai’i ........................................................................................ Duplominona kanehoei Karling, Mack-Fira & Dörjes, 1972

- cirrus large,> 40 rows of spines proximally 6 μm, distally 3 μm long, N. Australia........................................................................................ Duplominona cynaroides Martens & Curini-Galletti, 1989

26 - proximal and distal spines different...................................................................... 27

- proximal and distal spines similar, central spines different.................................................... 28

- proximal, central and distal spines different............................................................... 29

27 - cirrus long (130 μm); 20 rows of spines, proximally scale-like, with recurve apex, 2.5 μm long; distal spines 7.5 μm long, acutely triangular; S. Brazil.................................................. Duplominona mica (Marcus, 1951)

- cirrus short (30 μm), proximally scale-like, with recurve apex, 2.5 μm long; distal spines 3 μm long, broadly triangular; Caribbean..................................................................... Duplominona pusilla n. sp.

- cirrus 40–70 μm long, proximal spines acutely triangular, 6 μm long; distal spines recurve, with broad bases, 1.5–3 μm long; Caribbean............................................................. Duplominona bocasana n. sp.

28 - proximal and distal spines, 3–5 μm long, with a recurve tip; central spines straighter, more acutely triangular, to 8–9 μm long; Caribbean........................................................... Duplominona macrocirrus n. sp.

29 - proximal spines needle-shaped, 6 μm long; medially, spines 15 μm long; distal spines 3.5–4 μm long, wider, with recurve distal tips; Caribbean...................................................... Duplominona dissimilispina n. sp.

- cirrus very small; proximal spines 3– 5 μm long, strongly recurve; medially, spines to 7.5 μm, with long tips; distal spines 2 μm long; Caribbean...................................................... Duplominona chicomendesi n. sp.

- proximal spines acutely triangular, 6 μm long, becoming smaller and with recurve tips medially; very small, scale-like distally; Caribbean........................................................ Duplominona puertoricana n. sp.

Figures

FIGURE 1. Duplominona aduncospina n. sp. (A) Habitus of a living animal. (B, C) Reconstructions of the copulatory cirrus (B: everted; C: inverted) showing the sclerotised copulatory structures. (D) Reconstruction of the genital organs from sagittal sections. (E) Micrograph of a sagittal section of the genital organs. (F) Micrograph of the genital area of a living animal. (Scale bars: B, C = 5 m; E = 20 m).

FIGURE 2. Duplominona terdigitata n. sp. (A) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features (B) Reconstruction of the everted cirrus showing the sclerotised copulatory structures. (C) Micrograph of a living animal. (D, E) Micrographs of sagittal sections of copulatory (E) and accessory (E) organs. (F) Reconstruction of the genital organs from sagittal sections. (Scale bars = 10 m).

FIGURE 3. (A–E) Duplominona pusilla n. sp. (A) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (B) Reconstruction of the inverted cirrus showing the sclerotised copulatory structures. (C, D) Micrographs of sagittal sections of the genital area. (E) Reconstruction of the genital organs from sagittal sections. (F–J) Duplominona bocasana n. sp. (F) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (G, H) Reconstructions of cirri (G: inverted; H: everted) showing the sclerotised copulatory structures. (I, J) Micrographs of inverted (I) and everted (J) cirri from a karyological slide (Scale bars = 10 m).

FIGURE 4. Duplominona dissimilispina n. sp. (A) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (B) Reconstruction of an inverted cirrus showing the sclerotised copulatory structures. (C, D, F) Micrographs of inverted cirri from karyological slides (C: Holotype; D, F: Paratypes). (E) Micrograph of a metaphasic plate. (Scale bars: B–D, F =10 m; E = 5 m).

FIGURE 5. (A–C) Duplominona chicomendesi n. sp. (A) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (B) Reconstruction of the inverted cirrus showing the sclerotised copulatory structures. (C) Micrograph of the inverted cirrus (Holotype). (D–G) Duplominona diademata n. sp. (D) Micrograph of a metaphasic plate. (E) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (F, G) Reconstruction (F) and micrograph (G) of the inverted cirrus of the Holotype. (Scale bars: B–D = 5 m; F, G = 10m).

FIGURE 6. (A–C, F, H) Duplominona macrocirrus n. sp. (A) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (B, C) Reconstruction (B) and micrograph (C) of the inverted cirrus of the Holotype. (F) Micrograph of a metaphasic plate. (H) Micrograph of the stylet of the accessory organ of the Holotype. (D, E, G, I, J) Duplominona puertoricana n. sp. (E) Habitus of a living animal; see Fig. 1 for interpretation of anatomical features. (D, I) Reconstruction (I) and micrographs (G) of inverted cirri (D: Paratype; J: Holotype) (G) Micrograph of a metaphasic plate. (Scale bars: A, B, H–J = 10 m; D = 25 m; F, G = 5 m).