The alien fissurellid Diodora ruppellii (G. B. Sowerby I, 1835): a first record for Libya from Tripoli Harbour

The mollusc Diodora ruppellii (G. B. Sowerby I, 1835) (Gastropoda: Lepetellida: Fissurellidae) is reported here for the first time as an alien species in Libyan coastal waters. Field surveys conducted throughout the winter period of 2018–2019 along the sandy shoreline bordering Tripoli Harbour yielded fourteen empty shells and one live specimen, all found within accumulating shell middens. While the finding of D. ruppellii in close proximity to Tripoli Harbour may allude to its introduction via shipping traffic, natural dispersal from nearby, known or yet undiscovered, Mediterranean populations cannot be ruled out. The current study forms part of a larger ongoing programme investigating the marine fauna of the littoral zone with a focus on the identification of non-native species. As D. ruppellii is so far recorded from Libya as based on the present punctiform record, we rank it here as a casual (i.e. not established) species in the country

First documented record of the invasive cockle Fulvia fragilis (Forsskal in Niebuhr, 1775) (Mollusca: Bivalvia: Cardiidae) in Libya

The occurrence of the fragile cockle Fulvia fragilis (Forsskål in Niebuhr, 1775) in Libyan coastal waters (south-eastern Mediterranean Sea) is reported here for the first time based on the collection of twenty-nine live specimens from the shoreline in close vicinity to Tripoli Harbour, situated to the west of the country. The present record fills a gap in the geographic range of F. fragilis – its occurrence is already documented from the neighbouring territories of Egypt, Italy, Malta, and Tunisia. Although there are no certainties regarding the precise arrival date of this non-native bivalve in Libyan coastal waters, its presence within the environs of Tripoli Harbour might allude to its facilitated spread through ballast water from commercial shipping activity

Description of Tresuncinidactylus wilmienae gen. et sp. n. (Monogenea: Gyrodactylidae), from the gills of the bulldog, Marcusenius macrolepidotus (Peters) from Lake Kariba, Zimbabwe

The African continent has a rich diversity of fish and amphibians in its inland water systems that serve as hosts for monogeneans of seven genera of the Gyrodactylidae van Beneden et Hesse, 1832. In August 2011, eight gyrodactylid parasites were collected from the gills of two specimens of bulldog, Marcusenius macrolepidotus (Peters), from Lake Kariba, Zimbabwe. Morphometric evaluation and sequencing of 18S rDNA confirmed that the specimens represented a species of a new viviparous genus, Tresuncinidactylus wilmienae gen. et sp. n. The attachment apparatus consists of a single pair of large slender hamuli with prominently flattened roots that are connected by a simple, narrow dorsal bar. The ventral bar is small and possesses a thin lingulate membrane but no evident anterolateral processes. There are 16 marginal hooks of one morphological type, but of three different sizes, with large falculate sickles that are proportionaly equal in length to the length of their handles. The two largest pairs of marginal hooks are positioned closest to the opisthaptoral peduncle, the neighbouring two pairs of medium-sized marginal hook sickles are situated along the lateral margins of the opisthaptor. Four pairs of smallest marginal hooks are positioned along the posterior margin of the opisthaptor. The male copulatory organ consists of a muscular pouch armed with approximately 30 gracile spines. Phylogenetic analyses of partial sequences of the 18S rDNA using Maximum Likelihood and Bayesian Inference placed the new genus within the lineage of solely African genera and suggests Afrogyrodactylus Paperna, 1968, Citharodactylus Prikrylova, Shinn et Paladini, 2017 and Mormyrogyrodactylus Luus-Powell, Mashego et Khalil, 2003 as genera most closely related to the new genus

New records of alien and cryptogenic marine bryozoan, mollusc, and tunicate species in Libya

New records of alien and cryptogenic invertebrate marine species in Libya are reported here based on field surveys conducted from June to November 2018, in a shallow bay next to the city of Tripoli. Those identified here include the cerithiid gastropod Cerithium scabridum Philippi, 1848, the goniodoridid sea slug Okenia longiductis Pola, Paz-Sedano, Macali, Minchin, Marchini, Vitale, Licchelli and Crocetta, 2019, the “spaghetti bryozoan” Amathia verticillata (delle Chiaje, 1822), and the ascidian Symplegma brakenhielmi (Michaelsen, 1904)

Zoothamnium duplicatum infestation of cultured horseshoe crabs (Limulus polyphemus)

An outbreak of the sessile peritrich Zoothamnium duplicatum in a pilot, commercial-scale Limulus polyphemus hatchery resulted in the loss of ∼ 96% (40,000) second/third instar larvae over a 61 day period. Peritich growth was heavy, leading to mechanical obstruction of the gills and physical damage. The peritrichs were controlled without resultant loss of juvenile crabs by administering 10 ppm chlorine in freshwater for 1 h and the addition of aquarium grade sand; a medium into which the crabs could burrow and facilitate cleaning of the carapace. Peritrich identity was confirmed from a partial SSU rDNA contiguous sequence of 1343 bp (99.7% similarity to Z. duplicatum)

Streptococcus agalactiae infection kills red tilapia with chronic Francisella noatunensis infection more rapidly than the fish without the infection

In this study we examined the effect that a Francisella noatunensis (Fno) infection had on hybrid red tilapia (Oreochromis niloticus × Oreochromis mossambicus) subsquently infected with Streptococcus agalactiae. A variety of hemato-immunological parameters (haematocrit, total red blood cell count, mean corpuscular volume, total white blood and differential cell counts, total plasma protein, plasma lysozyme and plasma peroxidase activities, and respiratory burst and phagocytic activities of head-kidney macrophages) were measured in hybrid red tilapia that had been previously exposed to an Fno outbreak in a tilapia grow-out farm. The head-kidneys of these apparently healthy survivors, when checked by PCR were found to be Fno-positive with hemato-immunological parameters that were similar to fish without an a priori infection. The only exception was the percentage lymphocyte count in the peripheral blood, which was slightly, but significantly, lower in the Fno-infected fish, compared to those without the infection. When experimentally infected with S. agalactiae, the Fno-infected fish died more rapidly and at a significantly higher rate than fish without the infection. During the challenge, the hemato-immunological parameters of both groups of fish were very similar, although the Fno-infected fish, challanged with S. agalactiae expressed significantly higher plasma lysozyme and peroxidase activities, and their head kidney macrophages had significantly higher respiratory burst activity compared to non-Fno-infected fish challanged with S. agalactiae. The only two parameters for which Fno-infected fish showed significantly lower expressions than that of their non-infected counterparts were haematocrit and total red blood cell count. The cause of the rapidity and higher rates of mortality observed in the Fno-infected fish when challenged with S. agalactiae is unknown; but it may be due to a reduced erythropoiesis capability within the head-kidney because of the presence of Fno

Prophylactic properties of biofloc- or Nile tilapia-conditioned water against Vibrio parahaemolyticus infection of whiteleg shrimp (Penaeus vannamei)

Isolates of Vibrio parahaemolyticus (VpAHPND) that carry a plasmid encoding two Pir-like toxins cause acute hepatopancreatic necrosis disease (AHPND), a disease that has caused devastating economic losses to the shrimp industry, particularly in Asia. However, lower prevalence of AHPND infection has been associated with farms that operate with biofloc or lower salinity culture water. Therefore, the aim of this present study was to investigate the effects of biofloc and Nile tilapia (Oreochromis niloticus)-conditioned water prepared at different culture water salinities on survival of whiteleg shrimp (Penaeus vannamei) bath-challenged experimentally with VpAHPND. First, groups of shrimp were bath-challenged with VpAHPND in clear 15 ppt seawater (CW) or in the presence of a pre-cultured biofloc at 25%, 50% and 100% (v/v). Survival during 96 h post-challenge was significantly greater in groups cultured in 50% and 100% biofloc (p

Histological damage and inflammatory response elicited by Monobothrium wageneri (Cestoda) in the intestine of Tinca tinca (Cyprinidae)

Background: Among the European cyprinids, tench, Tinca tinca (L.), and the pathological effects their cestodes may effect, have received very little or no attention. Most literature relating to Monobothrium wageneri Nybelin, 1922, a common intestinal cestode of tench, for example, has focused on aspects of its morphology rather than on aspects of the host-parasite interaction. Results: Immunopathological and ultrastructural studies were conducted on the intestines of 28 tench, collected from Lake Piediluco, of which 16 specimens harboured tight clusters of numerous M. wageneri attached to the intestinal wall. The infection was associated with the degeneration of the mucosal layer and the formation of raised inflammatory swelling surrounding the worms. At the site of infection, the number of granulocytes in the intestine of T. tinca was significantly higher than the number determined 1 cm away from the site of infection or the number found in uninfected fish. Using transmission electron microscopy, mast cells and neutrophils were frequently observed in close proximity to, and inside, the intestinal capillaries; often these cells were in contact with the cestode tegument. At the host-parasite interface, no secretion from the parasite's tegument was observed. Intense degranulation of the mast cells was seen within the submucosa and lamina muscularis, most noticeably at sites close to the tegument of the scolex. In some instances, rodlet cells were encountered in the submucosa. In histological sections, hyperplasia of the mucous cells, notably those giving an alcian blue positive reaction, were evident in the intestinal tissues close to the swelling surrounding the worms. Enhanced mucus secretion was recorded in the intestines of infected tench. Conclusions: The pathological changes and the inflammatory cellular response induced by the caryophyllidean monozoic tapeworm M. wageneri within the intestinal tract of an Italian population of wild tench is reported for the first time

Contributions of temporal encodings of voicing, voicelessness, fundamental frequency, and amplitude variation to audiovisual and auditory speech perception

Auditory and audio-visual speech perception was investigated using auditory signals of invariant spectral envelope that temporally encoded the presence of voiced and voiceless excitation, variations in amplitude envelope and F-0. In experiment 1, the contribution of the timing of voicing was compared in consonant identification to the additional effects of variations in F-0 and the amplitude of voiced speech. In audio-visual conditions only, amplitude variation slightly increased accuracy globally and for manner features. F-0 variation slightly increased overall accuracy and manner perception in auditory and audio-visual conditions. Experiment 2 examined consonant information derived from the presence and amplitude variation of voiceless speech in addition to that from voicing, F-0, and voiced speech amplitude. Binary indication of voiceless excitation improved accuracy overall and for voicing and manner. The amplitude variation of voiceless speech produced only a small increment in place of articulation scores. A final experiment examined audio-visual sentence perception using encodings of voiceless excitation and amplitude variation added to a signal representing voicing and F-0. There was a contribution of amplitude variation to sentence perception, but not of voiceless excitation. The timing of voiced and voiceless excitation appears to be the major temporal cues to consonant identity. (C) 1999 Acoustical Society of America. [S0001-4966(99)01410-1]

Gyrodactylus molweni sp. n. (Monogenea: Gyrodactylidae) from Chelon richardsonii (Smith, 1846) (Mugilidae) from Table Bay, South Africa

Gyrodactylus molweni sp. n. is described from the body surface and fins of the South African mullet, Chelon richardsonii (Smith, 1846) collected from Table Bay Harbour, Cape Town and is compared to five other Gyrodactylus species described from grey mullets globally namely G. zhukovi Ling, 1963 and G. mugili Zhukov, 1970 from Planiliza haematocheila (Temminck and Schlegel, 1845); G. mugelus Rawson, 1973 from Mugil cephalus L.; G. curemae Conroy and Conroy, 1985 from Mugil curema Valenciennes, 1836 and G. xiamenensis Zang,Yang and Liu, 2001 from Planiliza macrolepis (Smith, 1846). Morphologically, G. molweni sp. n. has prominent ventral bar processes that near cover the hamulus roots, marginal sickles with large rhomboid heels, slender shafts and fine points that extend beyond the sickle toes. Gyrodactylus molweni sp. n. can, however, be readily differentiated: G. mugili and G. xiamenensis have ventral bars with small ventral processes; G. zhukovi has marginal hooks sickles with slender shafts and proportionately short points and open-faced blades; G. mugelus possesses marginal hook sickles with deep, rounded heels, forward slanting shafts and an angular, square line to the inner face of the blades. Although the length of the marginal hooks of G. curemae are similar to G. molweni sp. n., their hamuli are double the size. A GenBank BlastN search with the 931 bp sequence covering ITS1, 5.8S and ITS2 gave no close hits; the nearest species for which sequences are available is G. nipponensis Ogawa and Egusa, 1978 (identity 96.56%, 899/931 bp). The proposal of G. molweni sp. n. as a new species, therefore, is well supported by both the molecular and morphological analyses presented herein. This Gyrodactylus species is the first to be described from C. richardsonii and only the second Gyrodactylus species to be described from the marine environment off the African continent