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FIGURE 1 in A histology-free description of a new species of the genus Tetrastemma (Nemertea: Hoplonemertea: Monostilifera) from Hawaii and India

FIGURE 1. Tetrastemma freyae sp. nov. (A, B) holotype: lateral view of the head with everted proboscis (A) and dorsal view of the anterior body (B). (C, F, G) paratype: dorsal view of the anterior body (C); stylet apparatus (F, G). (D, E) two specimens from India, dorsal view (E, squeezed specimen under cover glass). Scale bars: (A-C), 0.5 mm; (D, E), 1 mm; (F), 100 µm; (G), 50 µm.

FIGURE 5. A–D in Higher classification of the Monostilifera (Nemertea: Hoplonemertea)

FIGURE 5. A–D, drawings of specimens referred to as Tetrastemma flavidum Ehrenberg, 1828 by different authors; E, Nemertellina yamaokai Kajihara et al., 2001. A, reproduced from Ehrenberg (1828–1831); head, dorsal view (right); anterior fragment of body (middle); posterior end (left); the eyes are anteroposteriorly separated; the rhynchocoel appears to extend half body length at most. B, reproduced from McIntosh (1873–1874); this species is commonly regarded by subsequent authors (e.g., Beaumont 1900; Wijnhoff 1912) as belonging in Nemertopsis Bürger, 1895; the rhynchocoel extends 2/3 of body in this species (Beaumont 1900). C, reproduced from Bürger (1895); the rhynchocoel extends into the posterior region of the body. D, reproduced with permission (license number: 4636460733834) from Strand & Sundberg (2005b, fig. 1A) (© 2005 Oxford University Press); the eyes are arranged at the corners of a square. E, reproduced from Yamaoka (1940); anterior body, dorsal view (right); head, ventral view (left); the eyes are anteroposteriorly widely separated; the rhynchocoel is 30–60% of the body length (Kajihara et al. 2001). A–C and E are in the public domain.

FIGURE 4. Malacobdella japonica Takakura, 1897 in Higher classification of the Monostilifera (Nemertea: Hoplonemertea)

FIGURE 4. Malacobdella japonica Takakura, 1897 (ICHUM 5973), transverse sections through ventral rhynchocoel wall; A, anterior end, branch from mid-dorsal vessel, with basophilic contents (arrowhead); B, mid-dorsal vessel (arrowhead), 24 µm posterior to A; C, D, another branch (black arrowheads) with basophilic contents, sent off from mid-dorsal vessel (white arrowheads), 208–232 µm posterior to A. Scale bar: 20 µm (A–D).

FIGURE 3. A–B in Higher classification of the Monostilifera (Nemertea: Hoplonemertea)

FIGURE 3. A–B, Amphiporus lactifloreus (Johnston, 1828) (ICHUM 3280); A, anaesthetized living specimen; B, transverse section showing vascular plug (arrowhead); C–E, Quasitetrastemma stimpsoni (Chernyshev, 1992) (C, D, unregistered specimen, 3 July 2004, Akkeshi; E, ICHUM 5972); C, dorsal surface at anterior end, anaesthetized living specimen; D, ventral surface at anterior end, anaesthetized living specimen; E, transverse section showing vascular plug (arrowhead). Scale bars: 2 mm (A); 50 µm (B, E); no scales for C, D.

FIGURE 2. A in Higher classification of the Monostilifera (Nemertea: Hoplonemertea)

FIGURE 2. A, 'Emplectonema' mitsuii Yamaoka, 1947 (ICHUM 5968), transverse section immediately behind proboscis insertion, showing cephalic vessels (arrowheads) with medially modified epithelium; B–D, Gononemertes parasita Bergendal, 1900 (ICHUM 5971); B, dorsal surface at anterior end, anaesthetized living specimen; C, ventral surface at anterior end, anaesthetized living specimen; D, transverse section through brain ring, showing cephalic vessels (arrowheads) protruding into the rhynchocoel; E–G, Oerstedia dorsalis (Abildgaard, 1806) (ICUM 3274); E, anaesthetized specimen in living state; F, G, transverse sections through brain ring, showing cephalic vessels (arrowheads) protruding into rhynchocoel; H, I, Oerstedia polyorbis Iwata, 1954 (H, ICHUM 3287; I, ICHUM 3288), transverse sections through brain ring, showing cephalic vessels (arrowheads) protruding into rhynchocoel. Scale bars: 100 µm (A, D); 50 µm (F–I); no scales for B, C, E.

FIGURE 1 in Higher classification of the Monostilifera (Nemertea: Hoplonemertea)

FIGURE 1. Three different interpretations on the character evolution of rhynchocoel-wall composition among Monostilifera, mapped on topologically the same cladogram. A, if the last common ancestor of monostiliferans had a two-layered rhynchocoel wall (t), the interwoven state (i) would evolve twice; B, C, if the ancestral state was the interwoven one, either the last common ancestor of Eumonostilifera (= Plectonemertidae + Oerstediidae + Amphiporina) would acquire the two-layered state (B), or Oerstediidae and Amphiporina independently evolved the two-layered rhynchocoel walls (C); in either case, the loss of a single vascular plug on the mid-dorsal vessel (l) must have happened at the last common ancestor of Oerstediina (= Plectonemertidae + Oerstediidae), in which cephalic vessels protrude into the rhynchocoel when passing through cerebral ring.

opencc-zeroDec 2015View details →

dryad32/100

Data from: At least some meiofaunal species are not everywhere. Indication of geographic, ecological and geological barriers affecting the dispersion of species of Ototyphlonemertes (Nemertea, Hoplonemertea)

Most meiofaunal species are known to have a broad distribution with no apparent barriers to their dispersion. However, different morphological and/or molecular methods supported patterns of diversity and distribution that may be different among taxa while also conflicting within the same group. We accurately assessed the patterns of geographic distribution in actual genetic species of a marine meiofaunal animal model: Ototyphlonemertes. Specimens were collected from several sites around Europe, Northern and Central America, Southern America, Pacific Islands and Asia. We sequenced regions of two mitochondrial and two nuclear genes. Using single-gene, a concatenated data set, multilocus approaches and different DNA taxonomy methods, we disentangled the actual diversity and the spatial structures of haplotypes and tested the possible correlation between genetic diversity and geographic distance. The results show (i) the importance of using several genes to uncover both diversity and highlight phylogeographic relationships among species and that (ii) independent genetic evolutionary entities have a narrower distribution than morphological species. Moreover, (iii) a Mantel test supported a positive correlation between genetic and geographical distance. By sampling from the two sides of Isthmus of Panama, we were additionally able to identify lineage divergence times that are concordant with vicariance mechanisms caused by the geological closure of the seaway across the Isthmus. We therefore propose that in addition to distance, other geological and ecological conditions are also barriers to the dispersion of and gene flow in marine meiofaunal organisms.

FIGURES 1016 in A new genus and species of monostiliferous hoplonemertean (Enopla: Hoplonemertea: Monostilifera) from New Zealand

FIGURES 1016. Vulcanonemertes rangitotoensis gen. et sp. nov. 10, Transverse section through the junction between the pyloric canal and intestine. IN, intestine. PR, proboscis. 11, Transverse section through a cephalic blood vessel to show the appearance of the vacuolar 'pouches'. 12, Transverse section through a lateral nerve cord to show the accessory lateral nerve, indicated by an arrow. LN, lateral nerve cord. 13, Transverse section through a lateral nerve cord with the accessory lateral nerve, indicated by an arrow, running separately above it. 14, Transverse section through a lateral nerve cord in a region where the accessory lateral nerve has divided to form two neural tracts. 15, Transverse section through an efferent excretory tubule. 16, Transverse section through part of the head to show the appearance of the cephalic glands. CG, cephalic glands. DE, dermis.

FIGURES 38 in A new genus and species of monostiliferous hoplonemertean (Enopla: Hoplonemertea: Monostilifera) from New Zealand

FIGURES 38. Vulcanonemertes rangitotoensis gen. et sp. nov. 3, Transverse section through part of the body wall in the foregut region, showing the organisation of the body wall muscle layers. The diagonal muscle layer is indicated by an arrowhead. LM, body wall longitudinal muscle layer. 4, Transverse section through the stomach region to show the thin circular somatic muscle layer, indicated by arrows. The anterior pouches of the intestinal caecum are indicated by stars. PR, proboscis. RC, rhynchocoel. ST, stomach. 5, Transverse section through the foregut region to show how the cephalic glands extend behind the brain as lateral blocks of tissue, and the dorsoventral muscle fibres, indicated by arrows, passing on either side of the lateral blood vessels and nerve cords. CG, cephalic glands. LM, body wall longitudinal muscle layer. LN, lateral nerve cord. LV, lateral blood vessel. 6, Transverse section to show the organisation of the anterior portion of the proboscis. PE, proboscis epithelium. RC, rhynchocoel. 7, Transverse section through part of the head, showing oblique and radial muscle fibres running between the cephalic glands. CG, cephalic glands. CO, cerebral sensory organ. 8, Transverse section through the proboscis stylet bulb to show five accessory stylet pouches. The stylet bulb canal is indicated by an arrow. RC, rhynchocoel. SB, stylet basis.

FIGURE 2 in A new genus and species of monostiliferous hoplonemertean (Enopla: Hoplonemertea: Monostilifera) from New Zealand

FIGURE 2. Vulcanonemertes rangitotoensis gen. et sp. nov. Camera lucida drawing through the stomach region in crosssection to show the arrangement of the various body structures. AS, acidophilic spheres; CG, cephalic gland; CM, body wall circular muscle layer; DE, dermis; DM, body wall diagonal muscle layer; DV, middorsal blood vessel; EP, epidermis; EX, excretory tubule; LM, body wall longitudinal muscle layer; LN, lateral nerve cord; LV, lateral blood vessel; PR, proboscis; RC, rhynchocoel; ST, stomach.

FIGURE 1 in A new genus and species of monostiliferous hoplonemertean (Enopla: Hoplonemertea: Monostilifera) from New Zealand

FIGURE 1. Vulcanonemertes rangitotoensis gen. et sp. nov. Drawings of a complete specimen (A) and enlargement of the head viewed dorsally (B), based on sketches made in life, to emphasise the distribution of the eyes and appearance of the posterior pair of cephalic furrows.

FIGURES 1720 in A new genus and species of monostiliferous hoplonemertean (Enopla: Hoplonemertea: Monostilifera) from New Zealand

FIGURES 1720. Vulcanonemertes rangitotoensis gen. et sp. nov. 17, Transverse section through part of the head to show two of the ocelli. 18, Transverse section through one of the short, anterior cephalic furrows; the arrow indicates a ciliated canal leading to a cerebral sensory organ. EP, epidermis. 19, Transverse section through an ovary to show an egg. OV, ovary. 20, Transverse section through the posterior region of the body showing several of the basophilic, vacuolar structures (indicated by arrows) which are interpreted as some form of parasite. IN, intestine.

FIGURES 15–20. Korotkevitschia pelagica. 15 in Redescription of Korotkevitschia pelagica (Korotkevitsch, 1961) (Enopla: Hoplonemertea: Cratenemertea), a pelagic nemertean from Antarctica

FIGURES 15–20. Korotkevitschia pelagica. 15, Oblique section through the anterior part of stomach to show the mouth opening, indicated by an arrow. ST, stomach. 16, Transverse section through pylorus, indicated by an arrow. IC, intestinal caecum; PR, proboscis. 17, Transverse section through the middle region of the body. Lateral nerve cords are indicated by arrows. IN, intestine. 18, Transverse section through the middle part of the rectum. The middorsal blood vessel is indicated by an arrow. LN, lateral nerve cord, RE, rectum. 19, Transverse section through the posterior part of the rectum showing sphincter of circular muscle (indicated by arrows). PC, posterior commissure of the nerve cords. 20, Transverse section through the testis. A lateral blood vessel is indicated by an arrow. IN, intestine; LN, lateral nerve cord; TE, testis.

FIGURES 9–14. Korotkevitschia pelagica. 9 in Redescription of Korotkevitschia pelagica (Korotkevitsch, 1961) (Enopla: Hoplonemertea: Cratenemertea), a pelagic nemertean from Antarctica

FIGURES 9–14. Korotkevitschia pelagica. 9, Transverse section through the stylet region of the proboscis. CE, "clot" of extracellular gel; SP, stylet pouch with accessory stylets. 10, Transverse section through the proboscis just behind stylet region to show subepithelial acidophilic glands (indicated by arrows). CE, "clot" of extracellular gel. 11, Oblique section through the anterior part of the head showing circumrhynchodaeal glands (indicated by arrows). 12, Transverse section through the left lateral nerve cord (LN) to show the band of connective tissue with myofibrils (indicated by an arrow). 13, Oblique section through the cerebral organ to show the sensory canal, indicated by an arrow. BR, brain; CO, cerebral organ; LP, lateral pouches of intestinal caecum. 14, Transverse section through the efferent canal (indicated by an arrow) of the excretory system. IN, intestine; LN, lateral nerve cord.

FIGURE 8 in Redescription of Korotkevitschia pelagica (Korotkevitsch, 1961) (Enopla: Hoplonemertea: Cratenemertea), a pelagic nemertean from Antarctica

FIGURE 8. Korotkevitschia pelagica. Schema of organization of middle proboscis portion. AG, acidophilic glands; CE, "clot" of extracellular gel; GE, outer glandular epithelium; IC, inner circular muscle layer; LM, longitudinal muscle layer; NS, neural sheath; OC, outer circular muscle layer; OE, outer epithelium of posterior proboscis portion; PN, proboscis nerve; PP, posterior proboscis chamber; SP, stylet pouch with accessory stylets.

FIGURE 1 in Redescription of Korotkevitschia pelagica (Korotkevitsch, 1961) (Enopla: Hoplonemertea: Cratenemertea), a pelagic nemertean from Antarctica

FIGURE 1. Korotkevitschia pelagica. Schema of internal organization of anterior portion in lateral view. BR, brain; CG, cephalic glands; CM, body wall circular muscle layer; CO, cerebral sensory organ; CR, circumrhynchodaeal gland cells; CV, cephalic blood vessel; DC, dorsal cerebral commissure; DE, dermis; EX, excretory tubules; FO, frontal organ; LM, body wall longitudinal muscle layer; LN, lateral nerve cord; LV, lateral blood vessel; LP, lateral pouches of intestinal caecum; PS, precerebral septum; RC, rhynchocoel; RD, rhynchodaeum; RM, cephalic retractor muscles; RP, rhynchopore; RS, rhynchodaeal sphincter of circular muscles; ST, stomach; VC, ventral cerebral commissure; VP, vascular plug of dorsal blood vessel.

FIGURES 2–7. Korotkevitschia pelagica. 2, Oblique section through a in Redescription of Korotkevitschia pelagica (Korotkevitsch, 1961) (Enopla: Hoplonemertea: Cratenemertea), a pelagic nemertean from Antarctica

FIGURES 2–7. Korotkevitschia pelagica. 2, Oblique section through a frontal organ. FO, frontal organ. Cephalic retractor muscles are indicated by arrows. 3, Oblique section to show body diagonal muscles, indicated by arrows. 4, Oblique section through the stomach wall. The stomach protrusion is indicated by the black arrow, the longitudinal fibres around the stomach wall are indicated by white arrows; ST, stomach. 5, Oblique section through the canal of the cerebral organ. The sensory canal is indicated by an arrow, the radial fibres are indicated by arrowheads. BR, brain; CO, cerebral organ. 6, Oblique section through the anterior part of the rhynchodaeum. The circumrhynchodaeal glands are indicated by an arrow. RD, rhynchodaeum; ST, stomach. 7, Oblique section through the rhynchocoel wall.

FIGURE 9 in A new genus and species of monostiliferous hoplonemertean (Enopla: Hoplonemertea: Monostilifera) from New Zealand

FIGURE 9. Vulcanonemertes rangitotoensis gen. et sp. nov. Drawings of the central stylet and basis from a young specimen (A), with a stylet:basis ratio of about 2:1, and from a larger individual (B) where the ratio is about 1:1. CS, central stylet. SB, stylet basis.

opennotspecifiedDec 2007View details →

FIGURE 8 in Two species of Nemertopsis (Nemertea: Hoplonemertea: Monostilifera) living in association with Capitulum mitella (Crustacea: Cirripedia: Thoracica: Lepadomorpha)

FIGURE 8. Nemertopsis mitellicola sp. nov. Holotype, ZIHU-3204. A, transverse section through stomach, showing general arrangement of internal organs. B, enlargement of A, showing mid-dorsal epidermal furrow.