ANOTHER EGYPTIAN OCCURRENCE OF THE TERRESTRIAL SLUG SPECIES LAEVICAULIS STUHLMANNI (SIMROTH, 1895) (GASTROPODA: PULMONATA: VERONICELLIDAE) IN ASSIUT GOVERNORATE, UPPER EGYPT

a bstract : This paper reports on new records of the veronicellid slug, Laevicaulis stuhlmanni (Simroth, 1895) (Gastropoda: Pulmonata) from Egypt, in Assiut governorate, representing a considerable southern extension of its range. It was found in two locations: the ornamental nursery of Assiut University and at the Al-Muallimeen nursery in the same governate. Its association with various ornamental plants is noted, as are its morphological characteristics at different points in its life history. The observations contribute to knowledge of the distribution of terrestrial


INTRODUCTION
Species of terrestrial slugs (Gastropoda: Pulmonata) are among the most significant invertebrate pests of agricultural and horticultural crops.Despite their lack of a shell, making them vulnerable to desiccation (Barua et al. 2021), they flourish in sheltered and moistened habitats such as nurseries, greenhouses and gardens.Many species have been introduced accidentally beyond their natural ranges, being easily transported by human activities such as the plant nursery trade (brItton et al. 2010, bergey et al. 2014, alI 2017, HIrano et al. 2019).Many become invasive pests, causing substantial agricultural, medical and economic problems (raHel 2002), and they may displace native species (USDA APHIS 2010).
Among such invasive pests are slugs in the family Veronicellidae, also known as leatherleaf slugs (PaInI et al. 2016).They are flattened, with a large mantle covering the whole of the back (stocKs et al. 2014).They are hermaphrodite, and some, at least, are capable of self-fertilisation.This family contains species that are agriculturally significant, causing serious damage and losses to numerous ornamental and horticultural crops and gardens (raut 1999, naranjogarcía et al. 2007, brodIe & barKer 2011, gomes et al. 2013, caPInera & rodrIgues 2015, alI & robInson 2020).Containing 23 recognised genera, the family is widely distributed throughout tropical and subtropical regions of the world (gomes et al. 2010(gomes et al. , HIrano et al. 2019)).They are distributed across Central and South America, the West Indies, Sub-Saharan Africa, as well as southern and Southeast Asia.Furthermore, they have been introduced to numerous island groups within the Pacific The veronicellid slug Laevicaulis stuhlmanni (Simroth, 1895) has previously been recorded from Egypt only in Cairo, where it appears to be self-fertilising (alI 2017, alI et al. 2022).Its close relative, L. alte, has also been reported from nearby Giza (alI & robInson 2020).Here, we report on a second area of occupation, to the south in Assiut Governate, with notes on the slug's morphology, its plant preferences and its geographical distribution in Egypt.
The slugs were collected by hand under and around plant pots, where moisture and shade facilitated aggregations around plant stems, roots and water sources such as irrigation taps.Slugs were collected into labeled boxes and transferred to the laboratory.In addition, observations were made between April 2018 and March 2020 on the distribution of the slugs among different plants.Numbers were recorded, but the slugs were not collected.At the University nursery, other slugs were associated with L. stuhlmanni, such as Ambigolimax valentianus and Deroceras laeve.Snails such as Eobania vermiculata and Monacha obstructa were also found at both locations.

SAMPLE EXAMINATION AND IDENTIFICATION
Forty-seven specimens from both locations were collected into labeled plastic containers with holes for aeration and supplied with fresh lettuce leaves (Lactuca sativa L.) and then transferred to the laboratory of Agricultural Zoology and Nematology Department, Faculty of Agriculture, Al-Azhar University, Assiut Branch.The slugs were drowned in water and then preserved in 75% undenatured ethyl alcohol.
Specimens were sent to D. G. Robinson at USDA APHIS National Malacological Laboratory, and to R.

RESULTS
Laevicaulis stuhlmanni (Simroth, 1895) was found in the two nurseries for ornamental plants in the Assiut district, Assiut governorate, as listed above, in late April 2018.Typical sites are shown in Fig. 2; moist soil, shade, and warmth among the seedlings were the preferable habitats.These records double the number of sites at which veronicellid slugs are known in Egypt.The taxonomic status of this veronicellid slug is as follows:

THE DIAGNOSTIC CHARACTERS OF THE SLUG
The external appearance of the species is shown in Figs 3-4).The average body length of the 13 meas- ured specimens was 4.62±0.69(SD) cm (range 3.5-5.6cm with the mantle covering the entire length of the body).The body becomes more elongated when the slug is crawling.The foot is narrow and the pneumostome is not obvious.Additionally, the specimens had a posterior anus and eyes on contractile tentacles.The sensory tentacles are bilobed, and the colour ranges from light brown to dark mottled brown.This result is in accordance with the findings reported by alI (2017).Eggs were found while collecting samples from the field, during the activity season of the slug.The egg masses are a strip of transparent oval eggs that tend to elongate, tied together with a thin thread, and this strip is coiled, forming the mass.
As external characters are similar to those of other veronicellid slugs, and very variable, identification was based on the morphology of the reproductive organs.Diagnostic characters included traits of the male anterior genitalia (penial morphology and the structure of the digitiform gland); also, components of the posterior genitalia and the positioning of the male and female genital pores.
Eight slugs were dissected to examine the genitalia.The male genital pore opens in the anterior part of the body.The anterior male genitalia is composed of two parts, the phallus and the phallic gland that are both enclosed in a light white muscular sheath opens through the genital pore.On the proximal part, there are a number digitiform tubules, numbering around thirteen to fourteen tubules (Fig. 5), as also found by alI et al. ( 2022), who found digitiform tubules numbering from ten to seventeen with average 12.5 tubules.The female genital pore is located on the right hyponotum, posterior to the middle of the total length.The posterior genitalia are characterised by a more or less ovate-shaped hermaphroditic gonad (Fig. 6).It has a large convoluted hermaphroditic duct that connects to the albumen gland (Figs 6-7).A relatively long duct leads to the bursa copulatrix (Fig. 8).

MICROHABITAT DISTRIBUTION
The specimens were collected by hand from the ornamental plant seedlings, the surface of the soil between seedlings, under potted plants, in clay pots, plastic pots, and plastic seedling bags, under the wet wood panels, under fallen leaf litter and on ornamental plant seedlings .The slugs were found on various ornamental plants, these are: umbrella plant (Schefflera arboricola), desert petunia (Ruellia brittoniana), horseshoe geranium (Pelargonium zonale), dusty miller (Senecio cineraria), paperflower (Bougainvillea glabra), yucca (Yucca sp.), latania (Latania sp.), kalanchoe (Kalanchoe sp.) (Table 1).The ornamental plant ponds are irrigated daily, and slugs were observed among the seedlings near the water source in the nursery.Consequently, moisture is continuously present.The presence of eggs, feces, or mucus frequently indicates the habitat of a slug.
As a result of observing these slugs on plants during the investigation period, the highest incidence of slugs was on umbrella plant, where the average number of slugs exceeded 10 individuals per sample (0.25 m 2 ), while only a few individuals were found on dusty miller, latania, paperflower and kalanchoe plants, where the average number did not exceed five individuals per sample (0.25 m 2 ), during the study period.The body of L. alte is dark gray to nearly black body with a thin pale median dorsal line (HIrano et al. 2019).However, the genitals must be dissected to confirm the identity of the species.It remains to be seen if L. stuhlmanni also becomes a significant pest.Care will be needed to identify it accurately.

Fig. 2 .
Fig. 2. Two photos of the sample collection sites in Assiut governorate

Table 1 .
The occurrence rate of the terrestrial slug species Laevicaulis stuhlmanni on various plants in some locations at Assiut governorate, Upper Egypt